Understanding the Terroir of Burgundy Part 4.3 Erosion and Rills: Studies in Vosne-Romanée and Monthélie

Erosion in Vosne Romanee

In the water’s path

Erosion comes in two forms: the seen and the unseen.

Rill erosion is the most obvious form of erosion and typically occurs in heavier downpours of more than 30 mm (1.2 inches) over a 24 hour period. They begin in spots where soil aggregates are weakened, and will collapse with weight and friction of the water above it, forming the aqueduct-like channels into which the runoff will funnel. Rills often generate in flow zones,  gathers in the depressions between rows. Here water can consolidate, growing in volume and velocity as moves with increasing rapidity down the hillside. With the water growing in mass and speed, larger and larger soil particles are pulled with it, releasing from both the bottom and sides of the rill, developing their typically U-shaped trough. As rills go unrepaired, they can grow substantially,  that can be difficult to control, if measures are not already in place to prevent them.

Sheet erosion (aka surface erosion) is a precursor to, and happens simultaneously with, rill erosion. In this case, rainwater runoff moves in sheets across the surface of the vineyard, but between and through the vines in places where rills won’t, or have not yet, formed. Surface runoff has a less concentrated volume of water than the runoff that travels through rills, so it yields a lower speeds and less velocity. Because of this limited velocity, the water of surface runoff is capable of carrying particles with a lower suspension velocity than rills are capable. These may include sands, but unless the downpour was heavy, would primarily include clays and silts. In less intense storms (< 20mm) surface runoff can cause sheet erosion, but these actions are considered slightly erosive, typically transporting finer materials in weak aggregates. From year to year, soil loss to sheet erosion goes largely unnoticed as the topsoil loss directly beneath the vines disappears down the hillside forever.

  • For an explanation of erosional factors and concepts click here for part 4.2
  • For history of erosion and vineyard restoration in Burgundy click here for Part 4.1
  • For the history of erosion and man in Burgundy click here for Part 4.

 

2006 Study of erosion in Vosne-Romanée, Aloxe-Corton, and Monthélie

Two sibling studies, preformed by the same research team, illustrates very well the processes of erosion (detailed in part 4.2), and how it affects the wine we drink. These are multi-discipline studies by conducted by the team of Amélie Quiquerez, Jean-Pierre Garcia, and Christophe Petit from the Université de Bourgogne, and Jérôme Brenot from Géosciences Université de Rennes.

The first of the two studies was published in the Bolletino della Società Geologica Italiania 2006, with contributions by Philippe Davy, Université de Rennes. Entitled “Soil erosion rates in Burgundian vineyards (link).” It examined the erosion rates in the villages of Vosne-Romanée, Aloxe-Corton, and Monthélie. I highly encourage you to look at these important studies to get their analysis, which in some ways is limited by the rigors of science which require the researcher to prove what they already know to be true. My overview of the information revealed by their study applies my own perspective and insights.

The researchers selected three steep, upper-hillside vineyards from which to gather data, all which carried essentially the same average grade, with a mean of 10.5% for Vosne and Aloxe-Corton, with Monthelie the steepest, with a mean slope of 10.7%.  Additional selection criteria were all three were they must meet these three (very traditional Burgundian) vineyard practices.

  1. The rows ran vertically down the hillside.
  2. None of the plots were allowed to have grass grow between the vines.
  3. Frequent plowing or tractor crossings (up to 15 times per year)

However, I note two marked differences between the vineyards. 

  1. How much the slope changed within the plot boundaries.
  2. The length of the slope. 
Vosne Damodes
Vosne Damaudes photo: google earth

The study’s most uniform slope was a vineyard in Vosne, with a fairly consistent 10% to 12% grade. It also had, by far, the longest slope studied, at 130 meters.(1)  This longer slope length, one might expect, would allow water to gain volume, speed, and velocity. These three factors all increase the runoff’s ability to carry larger and heavier particles with higher suspension velocities. Conversely, it was the only slope studied which had a murger (stone wall) at its base, slowing the runoff enough to allow sedimentation to occur, and it would appear to be the only plot with a level spot for sedimentation to rest. 

Although unnamed by the study’s author, I have concluded this vineyard is Les Damaudes on the Nuit-St-Georges border. Clues to its identity include a maximum elevation of 345 meters – the highest in Vosne, and uniform slope of 10-12%. Identifying the parcel location is possible as well, as only one location in Les Damaudes is long enough to fit the 130-meter plot length of this study. When subtracting in the dirt roads at the top and bottom of the vineyard, which are natural erosional breaks, the total length is 126 meters. This vineyard was studied in-depth, over a multi-year period, and spawned the two studies I will detail in this article.

The vineyard in Aloxe-Corton may contain a significantly steeper section than the vineyard in Vosne, with a 17% grade, but overall the Aloxe-Corton vineyard had the same average gradient as the plot in Vosne, at 10.5%. This indicates that part of that vineyard had to contain no more than a 5% grade. Additionally, this vineyard was the shortest plot at 53 meters, meaning as long as fast-moving runoff could not enter the plot freely from above, runoff should not be able to attain the same velocity as it might in Vosne. Because of this, we might anticipate erosion lower erosional levels. There is no specific information that might allow us to identify this vineyard. And while the author Jérôme Brenot included a photo and a brief reference to the grand cru vineyard of en Charlemagne (regarding rill erosion down to the limestone bedrock), the lieu-dits  of en Charlemagne is in neighboring PernandVergelesses, not Aloxe-Corton

Monthelie Clou du Chenes
The section of Monthélie studied is snug against the Volnay border. Here in 2012, some grass is now being allowed to grow between the vines. The vineyard above, La Pièce-Fitte, has one plot that is in pretty poor shape, with gaps between vines, and rills that because of the slight off camber row orientation cut right up against the vines, rather than directly between the rows. photo: googlemaps click to enlarge

The slope in the study with the steepest section, by far, was in Monthélie. The plot there reaches a maximum pitch of 24.5%, but the average gradient is only slightly greater at 10.7%, which again indicates much of the vineyard is gentile in its declivity. This vineyard, which would become a 1er cru shortly after the study was published, is the vineyard of Le Clou des Chênes,(2) and this parcel appears to share a border with Volnay’s ez Blanches vineyard. The study measured nearly twice the plot-wide erosion at 1.7 mm (± 0.5 mm year) as they did in either Vosne or Aloxe-Corton. However, in some locations within Le Clou des Chênes had far greater erosional levels: measuring as deep as 8.2 mm (± 0.5 mm) per year.

Notable is that the time under vine is much shorter, having been planted 32 years before the study. This makes the losses all the more alarming for these steeper slopes because the knowledge of how to resist erosion has improved so dramatically in the past twenty years.  

Data collection and methodology

This much erosion surely has had a tremendous influence on the character of the wines produced from these vines.
This much erosion surely has had a tremendous influence on the character of the wines produced from these vines.

Determining these numbers involved a massive data collection effort, imputing vine measurements on a meter by meter scale. With 10,000 plants planted per hectare, this translates into thousands of data points are required to arrive at the final calculations.

Soil loss was determined by measuring the exposed main framework roots from the current soil level to the point of the graft cut. The graft is typically made 1 cm above the soil level at the time of planting, and with this measurement original soil level at the time of planting can be established (NEBOIT, 1983; GALET, 1993). By dividing this measurement by the number of years since planting, a relatively accurate average rate of erosion can be established. This method of using plants to give a historical record is called dendrogeomorphology, which is a geologic adaptation of dendrochronology, the study of trees and plants to determine the historical climatic record.

An unequal field of study

Photo: Jérôme Brenot et al
Photo: Jérôme Brenot et al

In the end, there was a single factor that differentiated these study vineyards: the road and the stone wall below the Les Damaudes vineyard in Vosne. Because of this road and wall, it also was the only vineyard that had an area at the base of the slope that was able to retain alluvial sediment. This proved to be an important last gasp defense regarding soil loss and allowed that sediment to be returned to the slope. With this material, workers could fill the rills in Vosne, that would grow into gullies down to the base rock in Aloxe-Corton and Monthélie.

The return of the sediment to fill the rills was preformed bi-annually in the Les Damaudes parcel. However, the owners of this vineyard were lucky rather than preventative. The wall was built as the headwall of the small clos that surrounds the vineyard below, and the access road that runs between the vineyards proved to provide the necessary flat collection area for the alluvium.

Inexplicably, the author chose to simply say that in Monthélie, the practice of returning  soil to the hillside had never been done, whereas in Vosne it had been practiced every two years. Strictly speaking this was true.  However when looking at satellite images of the vineyard, this statement appears somewhat disingenuous. In reality, the decision to plant the entire area Le Clou des Chênes in long rows without any roadways or other vineyard breaks, when coupled with the  parcel’s physical position on the hill, created a highly erodible vineyard in which no level “toe of the slope upon which might sediment gather. Returning sediment, that doesn’t exist, to the hillside is simply not possible. That does not excuse the vineyard owner from not removing vines to build a walls or taking other erosion prevention measures, but it also gives and indirectly assigns blame for this lack vineyard maintenance. The Aloxe-Corton parcel (where ever it was) is not mentioned as the owners never having returned alluvial sediment to the hillside, although this was apparently the case.

In 2006, the researchers took the adjacent photograph of Le Clou des Chênes, showing that rills had developed into gullies due to the lack of effective intervention by the grower. They also included photo looking up towards the Bois de Corton (which I have not included), with a rill/gully that extends down to the raw limestone base rock below.  In each photo, the vines roots can be clearly seen, having been exposed by the continuing erosion of these gullies. 

Study design: did the study reveal unexpected results?

In some ways, the wall below the parcel in Vosne was problematic to the study. The stone wall, and ability the return of the sediment by the grower directly impacted the amount of erosion recorded. The study’s author reports this in the write-up as: “by a factor of two”.  It not clear that the researchers anticipated this would be such a weighty factor when they formulated the study, since the focus of the study did not seem to take into account the effectiveness of wall in diminishing erosional forces. However the effect of the wall and the “anthropogenic factors” (meaning in these studies: the actions by man of returning the sediment to the hillside) certainly did have a dramatic effect on reducing the total soil lost, and the authors rightly took the opportunity to underscore the roll and value of murgers and clos as a primitive, but effective form of erosion control. (4)

But because of the wall (and the author’s eventual focus on it), other opportunities were lost. Since Les Damaudes in Vosne possessed the longest slope which also had the most consistent gradient, knowing how those factors affected erosion would have been instructional.  Had the erosion measurements been made before the anthropogenic resupply of the sediment to the slope, this information might have been gained. But since the measurements were taken after the rills were filled, ascertaining the impact of degree of slope and the length of the run can not be readily determined if the Vosne parcel is included in the analysis.

Further analysis of  meter by meter grid data, might answer some of these questions surrounding how much erosion is affected by increasing slope gradient and increasing slope length. Here the shorter Aloxe vineyard could have been compared to the top 53 meters of the steeper Monthélie vineyard. What were the erosional differences within these sections? What was the difference between erosion between the upper slopes and the lower slopes of the vineyards. Could these differences have been attributed to gradient or soil type? What were the soils left behind in the inter rows? Were they significantly different to the soils directly under the vines where the soil is more protected from rain strike and rill erosion? Then, if the full length of the Aloxe vineyard could be included, would there be greater erosion on the steeper sections where gravity has more effect? What about on the lower sections of the plot where increase water volume, speed and velocity might be expected to increase? It does not appear that these questions were asked by the study’s researchers in 2006.

It would be interesting if the data still exists and can be analyzed to examine those questions as well. It certainly would shed a more quantitative light on erosional forces on Burgundian hillside vineyards.

Study’s Opinion

In the opinion of the study, while in the short-term, erosion didn’t affect the vines production as long as the root system was not exposed, over time, the overall surface soil level declined despite the best efforts in Vosne to return the alluvial sediment to the hillside. At the time of the study, the most alarmed of growers had begun been attempting to restrict erosion by allowing grasses to grow between rows, shortening the length of rows and rebuilding walls. The authors suggest these processes be applied to all hillside vineyards.

The study of a single rain event in Vosne-Romanée

The second study released by this team in 2007 is far more detailed, focusing solely on the Damaudes vineyard. Entitled,Soil degradation caused by a high-intensity rainfall event (3) the paper details soil loss related to a single storm on June 11, 2004. This study is much more focused and is far more precise and instructional in its findings.

Vosne Damaudes erosion study
Click to enlarge.

The study’s centers on the erosional path, volume, and sediment type, as well as the net erosion levels measured in the vineyard after workers had returned sediment to the hillside, post-storm.

Soil analysis of the plot

The soils native to the vineyard are within this description from the text of the study. The prose is tight and dense so I will quote the author, Emmanuel Chevigny, here.

“The texture is rather homogeneous over the whole plot and is composed of 40% of clays and silts, 50% of gravels (2 mm to 10 mm) and a low sand and boulder content. The topsoils are ploughed (Mériaux et al., 1981). The argillaceous aggregates with polyhedral blunted to grained form are slightly structured. No pedogenetic segregation has been observed.”

The soil, as described, is a marl, with what I would think has a surprisingly high clay content for being this high on the slope. A better breakdown of clay and silt would be informative, because (as detailed in Part 2.1  and 2.2 regarding soil formation), clay is metamorphosed from limestone and other materials, and very fine in size, while silt is larger (between 0.0039 to 0.0625 mm), and not metamorphosed. Silts are often parented from quartz, which unlike limestone is not prone to chemical alteration, and thus will not produce clay minerals. The origin of this silt must have been transported from farther up-slope, having arrived in Les Damaudes through erosion.

The vineyard’s soil has a low sand content.

The author then writes about argillaceous aggregates, which are clay aggregates. In this sentence, they are writing about the type of soil structure found in the vineyard. Clays tend to form into blocky structures, where each clay units sides is the same shape or a cast of the aggregate next to it. In other words, when the blocky structures form, they are literally cast so that they fit together like a puzzle. Here he is saying that the edges of these casts of the aggregates have been blunted making them more grain like.  There is a soil type, classified as granular (grain-like), that is common to soils in grasslands with a high organic content, and Chevigny is clearly saying these are not granular soils.

Lastly, Chevigny notes that the researchers observed no pedogenetic segregation, meaning they could observe no identifiable soil creation nor the beginnings of soil horizons (sedimentary layering). This would lack of soil generation could be caused, in part, by plowing which disrupts soil horizons and encourages the erosion of weak young soils that have not developed into stronger aggregates. More on the concept of what soil is and pedogenesis later.

The gravel, or scree, which constitutes 45 percent of the vineyard’s soil makeup, (by definition) has slid into the vineyard by gravitational erosion, from higher on the hill. With the clearing of land and subsequent planting of the vines, this gravel has long ago been plowed into the clay-silt mixture. It is never mentioned by the study author, whether the scree is primarily limestone or not. Limestone is not a factor for these researchers, the particle size is squarely considered to be the issue.

By the numbers

While study revolves around the analysis of a tremendous amount of numerical data, to examine each piece of analysis is beyond the scope of this article, but their findings are none-the-less important and tells the story of erosion within a Burgundian vineyard very well. Below I’ve listed what I see as the most important changes to the hillside following this particularly heavy storm system:

  • Both rill and sheet erosion occurred, but rill erosion accounted for approximately 70% of all soil lost from the hillside.
  • A total of 13 rill erosion were noted, some forming a mere 30 meters from the upper plot boundary, that ran in straight lines down the slope, each time in the inter-rows.
  • Rills occurred across 59% of the inter-row area
  • The rills were U-shaped with strong vertical walls.
  • Estimated soil loss from the rills alone was 4.77 meters
  • A rill erosion for this rain event is estimated at 7.8 cubic meters (.275.5 cubic feet) and weighing roughly 6 metric tons (13,227 lbs)
  • An estimated 1.6 meters erosional material was deposited into 7 alluvial fans at the base of the plot.
  • The sedimentary fans consisted primarily of very fine sand to coarse sand that was between 63 μm (roughly the thickness of paper) to >2 mm. Only 10% of the fan sediment was silt clay fractions of less than 63 μm
  • Fan #4 had a total sediment area one-half of a meter cubed (.5m3).
  • The two rills that fed fan #4 had a total eroded area of .93m3  *
  • If 10% of the rill volume is sand, then 70 percent of the fan debris came from the rills while a remaining 30% must have come from surface erosion which fed into the rills and were deposited into the fans.
  • Topographic soil loss in inter-rows with rills was 3.9 mm, or 48 metric tons per hectare (105,800 lbs)  even after anthropogenic resupply of fan sediment to the hillside.
  • Mean (average) soil in non-rill effected vineyard area, was 1.4 mm, or 24 metric tons per hectare (52,900 lbs)

*1 cubic meter is equal to 1000 liters, or 6.29 oil barrels or 264 U.S. fluid gallons.

Storm size and frequency

Annual rainfall in the  Côte de Nuits is between 700 and 900 mm (27 inches to 34.4 inches) per year writes Chevigny, citing the Météo France weather service’s Atlas climatique de la Côte dOr 1994.*  The study also cites that storms with rainfall of more than 30 mm per day, occurred 10 times between 1991 and 2002. Nine of these rain event dropped between 30 and 50 mm, (1.1 inches to 2 inches) and a single storm dropped 63 mm (2.5 inches) of rain water per event/day. Based on this, we might expect that there have been 50 such events between planting and the 2006 study.

The storm event of June 11, 2004, was uniquely powerful because 40 mm fell in a two-hour period, which caused causing 3 times the annual erosion rate established by the 2006 study of 1 mm per year. Perhaps most importantly, the erosion of this single event is averaged into that 54 year period. This indicates that some years little erosion occurred. Because the study only includes storm records from 1991-2002, we can’t estimate the distribution of erosion over the span of these 54 years.

With global warming, storm intensity seems to be on the upswing in Burgundy, just as scientists have noted in other parts of the world. The severe hail events of 2012, 2013 and 2014, which centered over the hapless villages Pommard and Volnay, resulted in total crop loss for some growers.  In the Côte de Beaune, where precipitation and hail has recently been at its most extreme, has also been remarkably varied in its distribution. According to Jancis Robinson, in July of 2013, Volnay saw 57mm of rain (2.25 inches), while neighboring Monthelie only got 9.4mm. Needless to say, with this high degree of weather localization, these data figures are representative of the rainfall collection points only. There were likely areas of Monthelie that got much more rain, and areas Volnay that got much less rain than the data collection sites.  The massive storms of late November 2014 that saw 200-300 mm of rainfall along the Mediterranean coastline and into Austria, the Dijon saw 95 mm of rainfall over a 24 hour period. So, in terms of storms, it would appear that while the Côte d’Or gets regular, low volume rain events, it is by and large, relatively protected from major storm fronts.

*Current monthly statistics are can be found here, and the average rainfall in Dijon as of 2015 is 775 mm (30 inches) per year.

The sediment at the “toe of the slope” 

When examining sediment in the alluvial fans, researchers discovered that it was made up of 90% sand and 10% fine sediment. Fan number four, on which researchers focused their examination, contained nearly one meter of alluvial material. The fact that it contained little silt or clay, indicates that when the water became backed up at the stone wall, its movement did not slow enough for particles smaller than 63 μm (which includes all clays and silts) to fall out of suspension. This suggests there was a significant depth of water Then as the runoff began to gather enough volume to circumvent the murger, and continue downslope, it gained sufficient speed and velocity to quickly form rills in its path around the wall. The runoff carried virtually all particles smaller than fine sand out of the vineyard.

Study inconsistencies, and outdated or generic source material

Between the two articles, the explanation of soil and bedrock type differs. It is not clear why the authors of both studies would quote articles that are 35 to 45 years old, and that generic to the region rather than performing a shallow excavation themselves, in order to obtain information specific to that vineyard.

“The slopes are composed of Middle to Upper Jurassic limestones and marls (Mériaux et al, 1981) …“For example, the sandy-clayey screes (grèze litée) reach 3 meters on Comblanchien limestones in Vosne-Romanée.

In the second study they write:

“The hillslopes develop on Middle to Upper Jurassic limestones and marls, and are covered by colluvium soils of argillaceous-gravelly nature and formed by Weichselian cryoclastic deposits (grèze litées) reaching up to 3 m thick (Journaux, 1976).”

Writing of Comblanchien as a class of limestones is a red flag, as it is distinctly a singular type of limestone. Adding to the confusion is the soil percentages that at first appear to be attributed to the vineyard, are actually from the 1981 Mériaux et al study and generic to the  Côte d’Or. Later in the study, the percentage of sand is increased to >20% (from 10% sand and larger stones). 50% gravel content in the vineyard, which is cited in early in the text, is reduced to 45% later in the study write-up.

 

Computer modeling projects grain-size transition 

Computer projections of grain size changes after each major storm event.
Computer projections of grain size change after each major storm event. Click to enlarge

Because the researchers must begin their work with the soil percentages they observe, this 45% gravel, 40% clay/silt and 15% sand, was their starting point. It was quickly recognized that outgo of clay minerals, coupled with the simultaneous retention of sand would eventually change the vineyard make-up, so they developed a computer program to predict future changes in grain size distribution of the soil composition. Computer models showed after only 4-5 rain events of similar magnitude as the one in 2004, there would be significant changes to the soil makeup. The results of those projections are to the right.

Chevigny encapsulates their findings with this statement.

“…the results of our simulation clearly show that repeated rainfall events modify significantly and very rapidly surface soil grain-size distribution: after only a few events, the top soil has lost more than 30% of its fine material.”

The ultimate effect of this would be the loss of organic materials, nutrients and ultimately soil sustainability.

Study conclusion: vineyard practices enhance rill development and erosion

While the wall slows the net output of soil volume from exiting the plot, the most soils most viable for farming are being lost, while simultaneously, the soil texture and particle size are being irrevocably changed as the sand sediment is returned to the hillside, and disked back into the soil.

It is forwarded by the author, that this action, is part of the problem since rills continue to re-emerge in the same locations, year after year. They submit that ill propagation in the inter-rows is heightened by tilling and repeated passes tractors and foot traffic, and the regularity of rill spacing are evidence of this.  These practices, he writes causes decreased soil porosity (compaction) and restricts rainwater infiltration. Such wheeled ‘passage’ creates flow zones which increase the volume and velocity of runoff in a concentrated area, multiplying the quantity and size of material the runoff can carry. The evidence of these anthropologically created flow zones is the re-emergence of rills that return, repeatedly, in the same inter-rows, despite workers attempts to eliminate them by filling the rills and disking those areas.

It is clear the effort must be made to properly identify the flow zones and attempt to eliminate them but to do so is to understand their formation to begin with, and limit or eliminate that activity altogether.

For me, the results of the computer modeling and projections are not surprising. While this research team and Burgundian winemakers can only look forward to what is next, we have the opportunity to use this information to hypothesize what came before.  This will allow us to see the true arc of geomorphological progression in the vineyards, and thus how winemaking styles have and will continue to change in Burgundy.

Next UP:  Turning our understanding of the limestone Côte on its head

 

 


 

(1)  Vineyards typically are areas with no breaks or obstacles to slow or impede storm runoff, so longer vineyards tend to suffer more greatly from erosion. However, this was not identified as an erosional factor in the study write-up. The length of this Vosne vineyard was listed in the first study at 130 meters, while in the second study it was written as 126 meters.

(2)  Le Clou des Chênes’ increased prestige and vineyard value can be a tremendous incentive to better maintain a vineyard. The vines and vineyard appeared to be in good health in 2012, the last time googlemaps car drove up this stretch of road. Still, no murgers had been built as of that time.

(3) published by Emmanuel Chevigny of the Université de Bourgogne in 2007

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Understanding the Terroir of Burgundy: Part 3.3 The Upper Slopes

Shallow topsoil over hard limestone: a site of struggle

As I touched on in the introduction of slope position in Part 3.2, there are significant variables effecting which vineyards can produce weightier wines further up the slope. However, as a general rule, the steep upper-slopes are far less capable of producing dense, weighty and fruit filled Burgundies that are routinely produced on the mid and lower slopes.

The lack of water, nutrients and root space

The scree filled Les Narvaux in Meursault. photo: googlemaps
The scree filled Les Narvaux in Meursault. photo: googlemaps

In many of these upper vineyards, the crushed, sandy, and in some places powdery, or typically firmer and more compact, the marly limestone topsoil overlies a very pure limestone, such as Comblanchien, Premeaux and Pierre de Chassagne. Here, the extent of that the stone is fractured determines the vines ability to put down a healthy volume of roots to support both growth and fruit bearing activity. Any gardener can tell you that insufficient root space, whether grown above a shallow hardpan or in a pot, will cause a plant to be root bound and less healthy.

Because these steeper vineyards can neither develop, nor hold much topsoil to its slopes. The topsoil, which can be measured in inches rather than feet, tends to be very homogeneous in its makeup; a single horizon of compact, marly limestone, with a scant clay content of roughly 10-15%. The infiltration of rainwater and the drainage are one and the same. Retention of the water is performed almost solely by this clay content, and evaporation in this confined root zone can be a significant hazard to the vine. Fortunately rain in Burgundy during the growing season is common, although rainfall from April to October, and particularly in July, the loss of water in the soil is swifter than it’s replacement from the sky (Wilson, “Terroir” p120).

Infiltration Rates of Calcareous Soils

A study by A. Ruellan, of the Ecole National Supérieure Agronomique, examined the calcareous (limestone) soils of Mediterranean and desert regions, where available water and farming can be at critical odds.  He studied two major limestone soil types. The first was a light to medium textured, loamy, calcareous soil (60 – 80% CaCO3), and the second was a powdery and dry limestone soil with no cohesion. This second soil had a calcium carbonate content that exceeded 70%, and had 5% organic matter and a low clay content. The water holding capacity of this soil was a mere 14%. The depth of this soil was over 2 meters deep, which likely does not allow weathered clay accumulate near the surface, as it does in Burgundy.

Both limestone soils had very high permeability, with an infiltrate at a rate at a lightning fast 10 to 20 meters per day (or between 416 mm per hour and 832 mm per hour).  Even if rainwater infiltrated at half that rate through Burgundy’s compact limestone soils, it would virtually disappear from the topsoil. This is the area where the majority of the vines root system exists, and part of the root system responsible for nutrient uptake is within this topsoil region.  In this case of these soils, the vines must send down roots to gain water in the aquifer. Wittendal, who I wrote of in Part 3, suggests in that the vines literally wrap their roots around the stone, and suck the water from them.  I have seen little evidence that limestone actually absorbs water due to many limestone’s high calcium content and lack of porosity. This would be particularly true on the upper slopes under consideration now. It would be up to the roots to attempt to penetrate the stone in search of the needed water.

The root zone

Root development through soil
This slide represents the root development in shallow topsoil over a lightly fractured limestone base vs a deeper soil situation with four or five separate bedding horizons, such as exists lower on the slopes of burgundy.The effect infiltration rates have depends significantly on the distribution of vine roots. In most planting situations, 60 percent of vine roots are within the first two feet of topsoil, and have been known to attain a horizontal spread of 30 feet, although the majority of the root mass remains near the trunk.

By design, vines rely on the roots established within the surface soil – which is where nutrients (ie nitrogen, phosphorus, potassium) are found – to gain the majority of their sustenance. They send down deeper roots to gain water when it is not available nearer the surface. However in Burgundy, many of the steeper slopes present planting situations where not only is the soil very shallow, but the nutrients are poor. The limestone in these vineyards often is hard and clear of impurities, and within the same vineyard may vary significantly in how fractured the stone is. Because of this, in some locations vines have difficulty establishing vigorous root penetration of the limestone base, and this can dramatically limit the vine’s root zone.

Additionally, because of the soil’s shallow depth, , and because of the soils high porosity and low levels of clay and other fine earth fractions, only a limited volume of water can be retained

Water is critical for both clay’s formation and its chemical structure, and the clay will not give up the last of what it needs for it own composition. The evaporation rate of what little water there might remain, can be critically swift.

Rainwater’s infiltration of the limestone base, and its retention of water can also be limited where significant fracturing has not occurred. Any water that cannot easily infiltrate either the soil or the limestone base, will start downward movement across the topsoil as runoff. That means any vine that has been established in shallow topsoil, or the topsoil has suffered significant losses due to erosion, will be forced to send roots down to attempt to supply water and nutrients.

Vine roots and a restricted root zone

In non-cultivated, non-clonal vines, powerful tap roots are sent down for the purpose of retrieving water when it is not available in from the surface soils. However our clonal varieties are more “highly divided” according to the “Biology of the Grapevine” by Michael G. Mullins, Alain Bouquet, Larry E. Williams, Cambridge University Press, 1992. The largest, thickest, roots develop fully in their number of separate roots, by the vine’s third year, and are called the main framework roots. Old established vines in good health may have main framework roots as thick as 100cm (40 inches) thick. This main framework root system, in normal soils, typically sinks between 30 cm (11 inches) and 35 cm (13 inches) below the surface.  In shallow soils, they may hit hard limestone before full growth, and may have to turn away, or stop growing. Anne-Marie Morey, of Domaine Pierre Morey, echoes this in talking with Master of Wine, Benjamin Lewin, of their plot in Meursault Tessons. “This is a mineral terroir: the rock is about 30 cms down and the roots tend to run along the surface.”

From the main framework, grows the permanent root system. These roots are much smaller, between 2 and 6 cm, and may either grow horizontally (called spreaders) or they may grow downward (known as sinkers).  From these permanent roots grow the fibrous or absorbing roots. These absorbing roots are continually growing and dividing, and unlike the permanent roots, are short-lived. When older sections absorbing roots die, new lateral absorbing roots to replace them.

This cutaway of the topsoil of Gevrey Bel Air shows just how limited the root zone is in this premier cru vineyard. The Comblanchien below is being 'reconditioned' in this plot. More on this in a near future article. click to enlarge.
This cutaway of the topsoil of Gevrey Bel Air shows just how limited the root zone is in this premier cru vineyard. The limestone below is being ‘reconditioned’ in this plot. click to enlarge.

Although the permanent sinker roots may dive down significant depths, the absorbing roots (which account for major portion of a vine’s root system account for the highest percentage of root mass, typically only inhabit the first 20cm to 50cm, or between 8 inch and 19 inches of a soils depth (Champagnol,  Elements de Physiologie de la Vigne et de Viticulture Générale 1984). Clearly this is an issue if the topsoil is only 30 cm (12 inches) to begin with.  If the absorbing roots are not growing sufficiently on the sinkers, the vine must rely on the exceptionally poor topsoil of the marly limestone.

South African soil scientist Dr. Philip Myburgh found (1996) that restricted root growth correlated with diminished yields. He also found that the “critical limit’ of penetration by vine root was 2 MPa through a “growing medium”. Weakness in the bedrock, and the spacing of these weaknesses, contributed to a vines viability.

The vines on these slopes, on which there is limited fracturing of the harder, non-friable limestone, have difficulty surviving. These locations often shorten the lifespan of the vines planted there, compared to other, more fertile locations in Burgundy, where vines can grow in excess of 100 years. It is these vines, with barely sufficient nutrients that make wines that don’t have the fruit weight that I wrote of before, simply because they cannot gain the water and nutrients necessary to develop those characteristics. The amount of struggle the vine endures directly determines the wine’s weight, or lack of it.

It is ironic, that when we research the issues the catchphrases of wine describe, ie, the “vines must struggle”, or that a vineyard is “well-drained”, or the vineyards are “too wet to produce quality wine”, we see the simplicities, inaccuracies, or the shortcuts that those words cover up. Yet these catchphrases are so ingrained in wine writing, that we don’t even know to question them, or realize that they require significantly more nuance, or at minimum, point of reference. Yes, the vines on the upper-slopes are particularly well-drained. They do indeed struggle, sometimes to the point of producing vines are not healthy, and cannot the quality or the weight of wine that the producer (dictated by their customers) feels worthy of the price.

Extreme vineyard management

Blagny sous la dos d'Ane's shallow red soils produce a Pinot that is too light for the market to bear at the price it must be sold. photo: googlemaps
Blagny sous la dos d’Ane’s shallow red soils produce a Pinot that is too light for the market to accept – at the price it must be sold. photo: googlemaps

In Blagny, the Sous le dos d’Ane vineyard, which lies directly above the small cru of  Aux Perrières, has seen at least one frustrated producer graft their vines from Pinot Noir to Chardonnay. The Pinot, from the red, shallow, marly limestone soils, was felt to be unsatisfactorily light in weight. Not only would a lighter-styled, and minerally Chardonnay be well received, the producer will be able to sell it much more easily – and for more money because he could then label it as MeursaultSous le dos d’Ane, a much more marketable name.

Bel Air. More photos on this excellent website, and a terrific discussion in the comment section, albeit in French. Worth running through a translator. source: http://www.verre2terre.fr/
Bel Air. More photos on this excellent website, and a terrific discussion in the comment section. source: http://www.verre2terre.fr/

Producers in the Côte de Nuits rarely have the option to switch varietals. They typically must produce Pinot Noir to label as their recognized appellation. In the premier cru of Gevrey-Chambertin “Bel Air”, and Nuits St-Georges “Aux Torey”, growers have gone to the extreme lengths and expense of ‘reconditioning’ their plots. To do this, they must rip out their vines, strip back the topsoil and breaking up the limestone below. In the adjacent photo, a field of broken Premeaux limestone and White Oolite has been tenderized, if you will. The soil is replaced and the vineyard replanted. The entire process requires a decade before useful grapes can be harvested once again from the site, costing an untold number of Euros spent, not to mention the money not realize had the old vines been allowed to limp on. The same has been done in Puligny Folatières in 2007 by Vincent Girardin, and there again in 2011 by another unknown producer. Ditto with Clos de Vergers, a 1er cru in Pommard in 2009.

 

http://www.wineterroirs.com/2009/11/landscaping.html

click here: for the previous article, Understanding the Terroir of Burgundy: Part 3.2 The lower slopes

Understanding the Terroir of Burgundy: Part 3.2 The lower slopes

by Dean Alexander

° of Slope =  Soil Type + Soil Depth  → Wine Weight

In Part 3.1, I covered how the position and degree of slope determined the type of topsoil that lies there. In the next two sections, I will talk about how the position on the slope not only greatly influences topsoil composition but independent of winemaking decisions, is a significant determiner of the weight of the wine. In this section I will discuss this concept, focusing primarily on the vineyards below the slope, the flatlands vineyards most burgundy aficionados have traditionally ignored. This disdain for these lower-lying vineyards is changing because massive improvements in wine quality have made them relevant, and equally massive increases in wine prices have left them as the only wines tenable to those without the deepest of pockets. Additionally, sommeliers looking for high-quality wines of relative value, have begun to much more closely examine the wide-reaching Bourgogne appellations and the village level wines of the Côte d’Or. These are wines that fit price points and quality standards premier cru vineyards used to fill and often fill that void admirably.  


 The relationship of slope to wine weight

Soil depth and type can greatly determine wine weight and character
Soil depth and type can greatly determine wine weight and character

It has become increasingly apparent over the past decade, that there is a direct connection between the depth and richness of soil, to the weight of the wines produced from those vines. Vineyards that have a modicum of depth, and at least a fair amount of clay or other fine earth elements, coupled with a fractured limestone base, produce weightier wines. These vineyards typically exist from quite low on the slope to roughly mid-slope. The higher up the slope one goes, the more crucial it is that the stone below is well-fractured to be easily penetrated by vine roots. Softer limestone bases, like the friable, the fossil-infused crinoidal limestone, which is weakened by the ancient sea lilies trapped within it, or like clay-ladened argillaceous limestone, makes it possible to produce great wine from the steeper, upper-slopes. Examples of these vineyards include the uppermost section of Romanee-Conti and all of La Romanee, which sits above it. These appear to be rare exceptions, however.

Most wines produced from the steeper, upper slope vineyards, with shallower, marly-limestone (powdery, crushed-stone with low clay content) soils, lie over harder, purer limestone types like Comblanchien, Premeaux, and Pierre de Chassagne. These limestone types must have at least moderate fracturing and a high enough degree of ductile strain to plant above them. Wines from these types of vineyards are, without question, finer in focus and have greater delineation of flavor. It is not unusual for these wines to be described as spicier, more mineral laden, and have greater tannic structure. The short explanation is the upper-slope wines have less fruit to cover up their structure, while the wines from more gently sloped vineyards have more weighty fruit.  This fruit provides the gras, or fat, that obscures the structure of these weightier, more rounded wines. The upper slope vineyards will be covered in greater depth in the upcoming Part 3.3.

Because of the weathering of limestone on the upper slopes, and subsequent erosion, the soils, and colluvium collect on lower on the slope, making the topsoil there both deep and heavy. They are full of a wider array of fine earth fractions, and more readily retain water and nutrients necessary for the vines health and propagation of full, flavorful, berries.  On the curb of the slope they do this splendidly, with an excellent mix of clay and colluvium, giving the proper drainage for the typical amount of rainfall, yet retaining the right amount of water most times of year when rain does not fall.

The last vineyard before the pastures begin. The village of Puligny Montrachet is in the distance
The last vineyard before the pastures begin. The village of Puligny-Montrachet is in the distance. source: googlemaps.com

The “highway” and the low-lying vineyards below

For decades we have been told that the low-lying vineyards of Burgundy, were too wet to grow high-quality grapes, and we could expect neither concentration nor quality, from these village and Bourgogne level vineyards. The reason, we were told, was grapes grown from these flat, low-lying vineyards became bloated with water, and the result was acidic, thin, and “diluted” village and Bourgogne level wines. Alternately we were told the wines from lower vineyards were too “flabby”, as James E. Wilson ascribes on in his groundbreaking book Terroir published in 1988 (p.128). Thusly, an entire swath of vineyards, from below the villages of Gevrey and Vosne, all along the Côte, all the way to down to Chassagne, were dismissed as thin and shrill, lacking both character and concentration. These wines were generally considered by connoisseurs to be unworthy of drinking, much less purchasing.  At that time, given the poor quality being produced, that seemed perfectly reasonable.

This set in motion a series of generalizations and biases, many of which remain to this day. “The highway”, as Route Nationale 74 is often referred, became the demarcation between the possibility of good wine and bad. The notion that this roadway, something that is built for the sole purpose of moving from one village to the next, had become an indicator of wine quality, is so pervasive, that the grand crus with N74 at their feet, such as MazoyèresChambertin and Clos Vougeot, have been cast in a bad light simply due to their proximity to it. It has colored perceptions so much, that many people, to this day, equate being higher on the slope with being “better situated”. The fact that there are grand crus and premier crus on the upper slope, but none on the lower slopes only buttressed this idea.  However…

We now know this is not true.

Puligny Folatieres after a rain
The road below Paul Pernot’s Clos des Folatières, filled with water. However, this water is not allowed to enter the 1er Cru of Clavoillon below. This is an example of containing and redirecting excess water coming down the hillside, into noncrucial areas. click to enlarge photo source: googlemaps.com

There are many Bourgogne level vineyards that are more than capable of producing wines with good concentration, so long as the vigneron sought to produce quality over quantity, and the plot is not in an excessively poor location. So why were these myths that Bourgogne level vineyards could only produce light, thin, acidic wines, propagated by winemakers, wine writers, and importers?

The optimist would point to a lack of technical knowledge in the field and cellar made this true. The optimist would also say that the long tradition of creating simple, inexpensive, quaffing wine made it acceptable.

But there were other factors. Cold weather patterns from the mini ice-age, which ended in the 1850s, certainly set up long-standing expectations of wine the wine quality that was capable from various vineyards. These expectations were absolutely cemented in after the widely influential book by Jules Lavalle, Histoire et Statistique de la Vigne de Grands Vins de la Côte-d’Or was published in 1855. In this revered reference, Lavalle classified the vineyards of Burgundy the same year the French Government classified the chateaux of Bordeaux. No doubt the timing of this gave Lavalle’s unsanctioned work credence. After the first half degree average temperature increase which occurred around 1860, the climate in central Europe only gradually grew warmer over the next 135 years until 1990 when global warming really began in earnest. Before that, the weather would not allow the consistent ripening patterns that routinely we see today.

Another major factor was that there was not a complete understanding of how to control and divert runoff. Nor, prior to 1990, was it likely the villages along the Côte wealthy enough to make the large-scale improvements that were necessary to control rainwater runoff. Until the prices of Burgundy began to rise, overall the region was experiencing some economic depressed. This economic struggle, coupled with the inevitable political obstacles required to spend sparse civic funds, could delay improvements a decade.

On the other hand, the skeptic would point to the problems of greed, and it’s accomplice, over cropping. Vignerons could achieve 3 to 5 times higher production levels from the same vines, which was profitable, and required far less knowledge, less diligence in the field, and other than taking up more labor in bottling and space in the cellars, far less work in the cellars. It was not only the Bourgognes that fell into this net of profit over quality, but the village level wines were often fairly low in concentration, with under-ripe fruit, and low in quality. Even now, a producer that has reduced yields by a division of 3 in order to make a quality village or Bourgogne, is making less money per hectare than they would if they still over-cropped – and working harder in the field to do it.

Overcoming wet soil issues

Water features below Puligny Les Pucelles. Controlling and redirecting water away from lower vineyards is a major key to improving quality there. photo: googlemaps
Water features below Puligny Les Pucelles. Controlling and redirecting water away from lower vineyards is a major key to improving quality there.  click to enlarge  photo: googlemaps.com

Excess water in lower vineyards is a serious issue, and each vineyard is not equal in its ability to contend with heavy rainfall. Although flat is the quickest descriptor, the topography of each vineyard varies, as does the bedding (layers of soil) of each vineyard. These variances can dramatically determine the challenges presented to each grower in each day, season, and year, be it rain storm or drought.

In farming, an infiltration rate of roughly 50mm of rainfall per hour is considered ideal. That is precisely what a well-structured loam can typically absorb at normal rainfall rates, without significant puddling and runoff. Clays, however, drain much more slowly, with an infiltration 10-20mm per hour.  These optimal figures can all be thrown out the window, however, if the soil structure has been degraded through compaction or farming practices that commonly degrade the soil. Poorly structured clay soils can drain as slowly as 5-8-10mm per hour.

Alluvial soils, with their graded bedding, created by heavier gravel and sand falling out of water suspension before silt and clays, typically have good infiltration rates. Loam soils that have moved in from the Saône Valley pasture lands, and have weaved themselves into the fabric of the lower vineyards, have ideal infiltration rates. Sandy sections are likely to exist in some vineyards, will have very rapid infiltration and drainage, 150mm to 200+ mm per hour. Where solid layers of transported clay, in thick slabs have formed, drainage can be severely affected.  These plastic-y clays may repel water as much as they slowly absorb it. I wrote a much more complete examination of soils in Part 2.2.

What is important to consider, is that in all but the upper-most vineyards, soils are layered in horizons of soil types. It is normal, around the world, that there are typically 5 horizons of soil and subsoil layers in any given place, although there may be more, or as on slopes, fewer. Each horizon will affect the drainage of the plot, depending on its soil makeup. Geologist Francois Vannier-Petit presided over an excavation of Alex Gamble’s village-level Les Grands Champs vineyard in Puligny-Montrachet. In this vineyard, she records two horizons within the 80 cms that they dug, and she noted most of the vines roots existed in this zone. At the time of the excavation, she noted the soil was damp, but not wet, with good drainage.

The calcium, which is freed from the limestone rubble with weathering on the upper slopes, is not as prevalent and effective in the farther-flung Bourgogne vineyards. The calcium which helps disrupt the alignment the clay platelets, and aiding is drainage, may not be carried far enough by runoff to sufficiently strengthen the soils of these more distant vineyards.  Certainly, most of these vineyards are located beyond the Saône Valley fault, and the continuation of limestone that virtually sits on the surface of the Côte lays buried by at least a hundred feet of tertiary valley fill and has no effect on wine quality there, other than by its remoteness.

flooding
Turbid flood waters carry away gravel, sand, and fine earth fractions. These will be redeposited as alluvial soils, created graded bedding and clay minerals will flocculate onto, or into, other transported clay bodies. photo: decanter.com

The most severe problems revolve around the maximum amount of water the soil or clay can hold and fail to drain quickly enough through to the unsaturated/vadose zone, through capillary action to the water table below. With clay, this is called the plastic limit, or the point just before the clay loses its structure and becomes liquid. Flooding would ensue, and large volumes of soil would become suspended in turbid flowing waters, causing massive erosion, particularly from vineyards up-slope. This would truly be the worst case event, and I won’t say it doesn’t happen.

Another, significant problem, at least for vintners, although less apparent to the wine drinking public, is less wet soil is that it causes the vines to have difficulty acclimating to colder weather, and affects their hardiness if severe weather sets in.

However, in many vineyards, the wet soil has now been addressed by investments in drainage. Large yields are eliminated and concentration is gained by pruning for quality, coupled with bud thinning or green harvest. Vigilance against rot is key in these lower vineyards, as well as odium, and other mildews, which thrive in humid wet vineyards. This is a key element in quality since rainfall during the growing season is very common in Burgundy. With all of these precautions, there are now many producers who now make excellent Bourgogne level wines. And despite the tripling and quadrupling of the prices of Bourgogne, they are now well-worth drinking – often equalling  the premier cru wines of yesteryear in terms of quality.

It is often cited that Puligny-Montrachet has no underground cellars because of the high water table there. Yet Puligny is arguably the finest region for growing Chardonnay in the world. I submit that much of the success Puligny has enjoyed, is in part because the water table is high, coupled with the fact that the village and its vignerons have invested heavily in water control features to channel and redirect excess runoff.

Reshuffling the wine weight matrix

The revelation that well-concentrated wines can be produced from these “wet” vineyards, has thrown slope position into a far clearer focus. No longer did we have lighter-to-medium weight wines on the upper slopes, the heaviest wine on the curb of the slope, and the very lightest wines coming from the lowest and flattest areas of Burgundy. Now it was clear: the areas with deeper, richer soils, particularly those with clay to marl soils, can universally produce richer fuller-bodied wines. This increasing quality of Bourgogne and the lower-situated village wines has dramatically raised the bar of expectations of wines across the Côte d’Or. With Bourgogne’s challenging the more highly regarded village-level vineyard in terms of quality, and village wines posing a challenge in regards to quality to many of the premier crus, lackluster producers were now put on notice to raise their game in terms of coaxing harmony and complexity out of their wines. Now that wine weight can be achieved in vineyards all across the Côte, despite a low slope position below the highway, expectation that Bourgognes are the simple, light and often shrill wines of yesteryear has been largely shattered.

Additionally, there is adequate evidence that deeper soils, particularly those with moderate-to-high levels of clay (or other fine earth fractions), can be a positive factor, for their ability to retain water and nutrients for the vines. This allows them to develop anthocyanins and other flavor components within the grapes. The challenge in these low-lying vineyards is controlling, and dealing with excess water.  In wet years, vignerons have demonstrated that adequate investment to direct and control runoff, even most lower vineyards will not be too wet to grow good to high-quality fruit. Examples abound of village crus, from top vignerons, costing more than many grand crus; and these producers Bourgognes are not far behind in price. It’s not magic; it’s investment and hard work, in a decent vineyard, that makes this kind of quality possible.

Author’s Note: To avoid misunderstanding, this is a discussion of wine weight and concentration, not wine quality or wine complexity. Too often these things are confused, along with the notion that increased enjoyment equals increased complexity or quality. The goal is to understand and appreciate the differences and nuances that each vineyard provides by its unique situation, not to make it easier to find the most hedonistic wine possible.

Understanding the Terroir of Burgundy: Part 2.1 From Limestone to Clay

© BiVB Latricieres
Latricieres under brewing storm clouds.  photo © BiVB

by Dean Alexander

The weathering of limestone: let it rain

flooding
Rain and Flooding

For the past 35 million years, rainwater has endlessly and relentlessly washed across the limestone escarpment. To varying degrees, the limestone will absorb water through its pores, but stone that has been damaged by ductile deformation is much more easily infiltrated. Faster still, water fills the cracks and fissures created by geologic strain, finding freshly broken calcium carbonate to wetten, and begin the process of chemical weathering called carbonation.

Rain rainwater, it seems is more than just H2o.  From the storm clouds above, H2o binds to with carbon dioxide (CO2) to form carbonic acid (H2CO3). And although carbonic acid is typically a mild acid when carried by the rainwater, it does slowly act as a solvent to the calcium carbonate (CaCO3) that holds the limestone together. This carbonation frees the carbonate from the calcium, and will metamorphose the calcium into calcium hydrogen bicarbonate Ca(HCO3)2, which technically only exists in solution. (1)  The material that remains behind once it is no longer bound by bonds of the stone, is whatever impurities that were in the stone when it formed. This could include clay, fossils, feldspar which is the most common mineral on earth), among many other possibilities.

Nature’s Highly Engineered, Deconstruction of Limestone

Calcium Bicarbonate photo credit: Frank Baron/Guardian
The calcium carbonate in limestone is made solvent by the carbonic acid in rainwater.  The calcium carbonate is metamorphosed into calcium hydrogen bicarbonate  or Ca(HCO3)2. Technically calcium bicarbonate exists only as a water solution. As long as enough CO2 remains in the water, calcium bicarbonate is stable. But once excess Co2 is released, calcium carbonate is dropped out of solution resulting in the scale like on the facet above. photo credit: Frank Baron/Guardian

Calcium carbonate is more soluble in colder temperatures.  If you aren’t paying attention, this, along with so many other pieces of information might seem fairly unrelated. But like everything else, it is an important piece of the puzzle. It is all part of nature’s finely detailed engineering, where every element directly is related to, and influences the next.

This fact that calcium is more soluble in colder temperatures folds beautifully together with the freeze-thaw fracturing of the limestone that I detailed in Limestone: Part 1.2. The acidic water enters the more porous limestone, where it then freezes. This exerts immense internal pressure on the rock, which causes it to split along the pores, can cause various types of fractures within the stone.  Then when the acidic ice within the rock begins to melt, it erodes the stone along the fissures, being aided by the cold temperatures. The more acidic the rainwater, the more minerals the groundwater can dissolve and be held in solution. Interestingly, because lime is alkaline (a base as opposed to acid) it naturally balances the ph of the water, and thus the soil, which is good for the health the vines.

Clay Development = great vineyards

Puligny excavation at Alex Gamble
An excavation of the village cru, Les Grands Champs by Alex Gamble and Francoise Vannier-Petit. According to Vannier-Petit’s analysis, below the first 30 centimeters of dark clay-loam soil, lies a fine-grained, yellow clay. In its most pure form it is typical of transported clay being less than 2 microns, before mixing with heavier soils of increasing size down to an 80 cm depth. Here it transitions to more loosened substratum of “angular gravel” of 2 mm in size, which she also terms “heterometric stones”, providing good drainage for the site. See more at alexgamble.com
Les Grands Champs
Visual observation: Les Grands Champs is located on the eastern edge of the village of Puligny. The land here is be quite flat, with less than a one percent grade.  It sits at the foot of the 1er cru Clavillions (where the road turns to head up hill). Folatieres lies just above that, the bottom of which is denoted by the by the plot being replanted.

Every Burgundy vineyard that is considered to be great has at least some clay and some limestone in their makeup. But that is not surprising since  clay, is the byproduct of the chemical weathering of stone. The silicate materials (essentially the building blocks almost all minerals) in the stone are metamorphosed into phyllosilicate minerals. Putting that more simply: after stone is eroded by acid, some of the weathered material (depending on what the stone was made of) is transformed into a material that will become clay – once it attracts the needed aluminum, oxygen, and water.

Clays first forms at the site (in situ) of the stone that is being weathered, and this typically is a form of surface weathering. This new material is a primary clay, and sometimes referred to as a residual clay. These primary clays tend to be grainy, lack smoothness, and do not typically have qualities that are described as plasticity. As primary clays are eroded, (typically by water) and are moved to reform in another location, they are called transported clays.

This transportation changes the clay’s properties; this is likely because the water carries the lighter, smaller gains together, away from the larger, coarser material that remains in the in situ location. When transported clay reforms, the reformation is called flocculation. This natural attraction that clays have toward homogeneous groupings, are due not only to their similar size but because they carry a net negative electrical charge, which the particles gain by adsorption. Adsorption is not to be confused with absorption, is like static-cling. Items are added, or adhered by an electrical charge, to the grains, not absorbed by the grains.

In flocculation, particles are attracted to one another, by their uniform size (typically very small, under 2 micrometers), and shape (tetrahedral and octahedral sheets). These phyllosilicate sheets organize themselves, layering one upon another, like loose pages of sheet music. Between these silicate sheets, aluminum ions and oxygen are sandwiched. These elements bind together to form a clay aggregate, even in the confluence of water. Clay formations can carry with them, varying mineral components such as calcium, titanium, potassium, sodium and iron and other minerals, making them available to the vines. To say that the chemistry of clay gets very complicated, very quickly, is an understatement.

Transported clay has plasticity, which primary clays do not. When a clay is very wet, beyond its liquid limit, (meaning the most water a clay structure can hold before it de-flocculates), the sheets slide apart, giving clay its slippery feeling. Any thick area of clay found at a location is likely to a be transported clay, as the adsorption characteristic of clay allows it to achieve significant mass.

Sand 0.02 – 2.00 mm in diameter
Silt 0.002 – 0.02 mm in diameter
Clay < 0.002 mm in diameterClay types

Francoise Vannier Petit at AlexGamble
Francoise Vannier Petit, inspects the yellow ocher-colored clay in Puligny-Montrachet, Les Grands Champs.  Clays get their pigmentation from various impurities. Brown clays get their color from partially hydrated iron-oxide called Goethite. This yellow ocher clay gets its color from hydrated iron-hydroxide, also known as limonite. Clay type, however, is not determined by its color, but instead by its chemical and material organization.
Different clay types can be found next to each other or layered on top of one another. This layering is called a stacking sequence. photo source: alexgamble.com

The type of clay that is produced from the weathering of rock depends on the what minerals make up the stone.  In the case of granite (the stone which existed in the Burgundy region, before the creation of limestone), is constructed of up to 65% feldspar, and a minimum of 20% quartz, along with some mica. While quartz will not chemically degrade in contact with the carbonic acid carried in rainwater, feldspar and mica will. Even though they originate from the same stone, these two minerals will metamorphose into two different of types clay, that belongs to two different clay family groupings. Feldspar weathers into Kaolinite clay minerals and mica weathers to an Illite clay mineral. These tend to be non-swelling clays. (3)

I probably spent twenty hours trying to figure out what kind of clay eroded from limestone, before I realized that it would depend on what impurities were mixed into the calcium carbonate when it was brewed up during the Jurassic period.  Limestone can produce any of the four families of clay.

Kandites (of which Kaolin(ite) is a subgroup), are the most common clay type, because feldspar, which is the world’s most common mineral, metamorphoses into it.

The other three clay groupings are smectite, illite, and chlorite.(4) Within these clay family groupings, there are 30 subtypes. As might be suggested by the example of the weathering of granite above, it is very common for different kinds clays reside adjacent to, or in layers with other clays. This layering of clay types is called a stacking sequence, and it can occur in either ordered or random sequences. Each are attracted to formations of its own type, by size weight, and electrical charge.

The Effect of  Weathered Limestone on Soil Quality

effect of lime on Clay
effect of lime on Clay

There are a number of significant benefits to the high levels of limestone in the soils of Burgundy. The world over, farmers make soil additions of agricultural lime (which is made from grinding limestone or chalk), in order to balance and strengthen their soils. These are additions that are unnecessary in Burgundy.  Soil salinity is increased by the calcium bicarbonate that is released by chemical weathering of limestone. This increase in soil salinity (which raises the pH) of the soil, is cited as a condition for the flocculation of the clay, allowing the phyllosilicates (clay minerals) to bind together into aggregates. But of course, citing a high ph is required for flocculation (as I have seen written by several authors) this is the chicken or the egg debate. The flocculation requires a low pH environment to occur because it creates that environment in process of its development.

Lime additions to agricultural lands are also beneficial in that it increases soil aeration, which in turn improves water penetration. The calcium loosened soils allow for better root penetration, and because of that root growth is improved. Additionally, agricultural lime strengthens vegetation’s cell walls, increases water and nitrogen intake, and aids in developing enzyme activity. Too much lime (and its accompanying salinity) in the soil, however, can be lethal to the vines, and various rootstock has been identified as being more resistant to the effects of high levels of limestone in the soil than others.

This loosening of soil by addition of lime/calcium carbonate is caused by the disruption of the alignment of the clay particles. Rather than doing a poor job paraphrasing an already excellent article from soilminerals.com, called “Cation Exchange Capacity,” which will I quote below.  To put the article in a frame of reference, it explains to farmers interested in organic and biodynamic farming, the proper mineral balance for healthy soils. These are conditions often exist naturally in the best sections of the slope in the Cote d’Or.

“Because Calcium tends to loosen soil and Magnesium tightens it, in a heavy clay soil you may want 70% or even 80% Calcium and 10% Magnesium; in a loose sandy soil 60% Ca and 20% Mg might be better because it will tighten up the soil and improve water retention. If together they add to 80%, with about 4% Potassium and 1-3% Sodium, that leaves 12-15% of the exchange capacity free for other elements, and an interesting thing happens. 4% or 5% of that CEC will be filled with other bases such as Copper and Zinc, Iron and Manganese, and the remainder will be occupied by exchangeable Hydrogen , H+. The pH of the soil will automatically stabilize at around 6.4 , which is the “perfect soil pH” not only for organic/biological agriculture, but is also the ideal pH of sap in a healthy plant, and the pH of saliva and urine in a healthy human.” soilminerals.com

Mud is the problem, lime is the solution
On construction sites, mud is a problem, and lime is the solution.

The industrial of use of limestone to control wet and unstable soil

The soil strengthening properties of lime is well known by the construction industry. It is used as a soil stabilizer in the construction of buildings and roadways, as well as being used to stabilize wet ground to improve the mobility of trucks and tractors. In the vineyard, soils with high levels of limestone provide the good porosity, soil structure, and drainage to clay soils, and as this construction advertisement depicts, the same for mud/dirt soils as well.

Lime is also the binding agent in cement. The first known use of lime in construction was 4000 BC when it was used for plastering the pyramids, and later the Romans extensively used lime in the preparation of mortar for various constructions. They found that mortars prepared from lime, sand, and water, would harden to a man-made limestone, with exposure to the carbon dioxide provided by the air. This, of course, sounds very familiar, knowing the formation and chemical weathering of stone.


 Next Up Soil Formation: Part 2.2, Soil, Slope and Erosion

NOTES

(1) I should note, that within the span of this short paragraph, carbon has seen several forms: in the air (in carbon dioxide CO2), as an acid (in carbonic acid CO3) carried by water, in stone as calcium carbonate CaCO3, as a mineral bi-product (as calcium bicarbonate Ca(HCO3)2 which exists in liquid solutions. This is all part of the carbon cycle, where carbon is regenerated in the air we breath, the water we drink, the earth we grow our food in.

(2) The fact that CO3 is now carried by water, is important in terms of vineyard development.

(3) Kaolinite clays are the type used in pottery.

(4) As Granite was the primary stone formation in the region prior to the development of limestone, it is likely that Kaolinite and Illites are the most common clay families in Burgundy today.

Understanding the Terroir of Burgundy: Part 1.2 Limestone: stress, deformation and fracturing

by Dean Alexander

The first steps toward vineyard formation

The world was a very different place 160 million years ago when the limestone was formed. Dinosaurs roamed the earth and Pangea was breaking apart.
The world was a very different place 160 million years ago when the limestone of the Cote d’Or was formed. Dinosaurs roamed the earth and Pangea were breaking apart.

Burgundy’s story really is one of stone into the earth, and pivots on a cast of geological stress, sub-freezing temperatures, and the simple, transformative power of water. Just how the forces of nature may have acted upon the limestone and transformed it into the great wine region it is today, is the subject of this article. Meanwhile, the ultimate goal of this series explains the intimate relationship limestone has with the wines of Burgundy.

I suspect that we all have this image of the Côte, post-Fault Event (however long that took), to be this raw 400-meter face of sheared limestone. But even then, the Côte was not a solid piece of stone. The incredible extensional forces the broke the Côte d’Or free from the Saône would have caused significant tension fracturing throughout the Côte before this much more massive fault gave way.

Just Add Water

just add water
just add water

This tensile fracturing, which surely was extensive, would allow rainwater to deeply infiltrate these fine crevices of the stone. And then, upon each surface that the water contacted, depending on the specific porosity and permeability of the limestone, rain water would penetrate the surface of the stone. This contact with water would set the stage for two very different yet significant developments in the stone.

With winter temperatures below freezing, the water in the stone will expand between 8 and 11 percent. This will yield 2000 pounds per square inch, or 150 tons per square foot of internal pressure which is more than enough  to cleave the stone. Geologists call this frost wedging, a form of mechanical weathering which breaks apart the stone due to thermal expansion and further with the eventual contraction. Thermal expansion has a culprit in shattering the stone: the cold. Most materials are inherently brittle in colder temperatures, and the limestone which has more elastic than brittle tendencies is more vulnerable to fracturing in freezing temperatures. Frost wedging is so successful in nature that the stone industry mimics it as a non-explosive technique to separate pieces of stone.

The effect of successive freeze thaw cycles, even upon undamaged exposed stone can cause the development of micro-fissures that influence the stone’s fatigue strength, and can produce vertical cracking called exfoliation joints, as well as flaking, and spalling. All along the Côte, there are numerous scars on hillsides where limestone has in the past loosened, to slide off of even moderate slopes, sending scree down the hillside to rest at the curb of the slope. Geologists refer to this rubble pile as colluvium, and it has proved a near perfect vineyard soil solution. The sliding and falling of rock further degrades the stone, abrading it as it slides, and breaking as it falls, allowing fresh broken surfaces for water to act on. Frost wedging which in part created this colluvium rubble pile, is considered mechanical weathering, and is the first development that I mentioned water would bring. Equally important to vineyard formation, is the second significant development that rainwater brings, is chemical weathering. The acid carried by the rainwater, will metamorphose these freshly broken limestone surfaces. And like magic, it will slowly dissolve the calcium carbonate which binds the stone, leaving behind clay minerals and other material.  (This process will be covered in Part 1.3 Clay and Soil Development)

Exfoliation and Other Theories on Geologic Structures with Unobservable Change

Gilbert's 1904 exfoliation weathering and unloading theory explained. Girraween National Park, Queensland
Gilbert’s 1904 exfoliation weathering and unloading theory explained. Girraween National Park, Queensland

Consider for a moment: most significant geologic changes occurs over a time frame that is far longer than the entire the evolution of mankind. This fact alone might best explain the difficulties of studying events that happen so slowly that change is not observable. These are geologic forces that can not be seen, felt, or measured. If we didn’t have evidence that these changes had occurred, we would

Like this granite, softer, more impure limestone can be prone to spalling, in part because of its porous nature. Stones, like granite, and softer limestones that have a significant amount of feldspar in their makeup, are more brittle because feldspar, and its bonds, are more brittle. Conversely, the calcium carbonate in limestone makes the material more elastic, because the chemical bonds of CO3 will tend to move or realign if the stress upon them is long and gradual. So the makeup of each limestone is critical to how prone it is to fracturing.
Like this granite, softer, more impure limestone can be prone to spalling, in part because of its porous nature. Stones, like granite, and softer limestones that have a significant amount of feldspar in their makeup. Feldspar, the most common mineral on earth, and its bonds, are brittle than calcium carbonate. Conversely, the calcium carbonate in limestone makes the material more elastic, because the chemical bonds of CaCO3 will tend to move or realign if the stress upon them is long and gradual. So the makeup of each limestone is critical to how prone it is to fracturing.

never know they were still continuing to occur around us. The scale of time and shear size and immobility of the objects makes many traditional scientific methods impossible.

Exfoliation Theory: G.K. Gilbert 1904

We know that exfoliation joints exist, but scientists are at odds about how they occur. It is agreed that mechanical strain results in large horizontal sheets of stone separating itself from the mother rock. Half Dome in Yosemite has achieved its shape in this manner. The first, and once long-held theory, was put forth by the ground breaking U.S. geologist Grove Karl Gilbert.  Gilbert’s theory of Mechanical Exfoliation concerned stone formations that had previously been buried in the earth’s crust, which were later were forced to the surface by geological up-shifts. The theory explained that the removal of the overburden (the weight of the rock or earth above) had caused unloading of stress in one direction. The resulting release of stress once on the surface and not confined upwardly, caused expansion and tensile cracking along unloading joints, eventually creating loose sheets of stone on the upper surface of these rock structures. These outer layer of stone were thusly being exfoliated. This website for Girraween National Park in Queensland, Australia, has an excellent explanation of exfoliation weathering.

Challenges to Exfoliation Theory

However, this theory has had it challenges by the mid 20th century, and is to some extent (depending on the point of view), muted or discredited.  Situations were sited that didn’t fit all of the theory’s criteria, like rocks that with exfoliation joints which have never been deeply buried, and evidence that many exfoliation joints exist in compressive stress environments, rather than being produces by extensional stress as the theory suggests. Alternative theories are thermal expansion, (and even wide diurnal expansion), and hydraulic expansion, , (which I discussed above with frost wedging), compressional stress, and in the case of Half Dome, the weight of gravity, or a combination of all of the above, including exfoliation weathering.

Along the same lines, theories revolve around minerals that are created in an anaerobic environment. These stipulate some minerals molecular structure are changed (metamorphized) when exposure to oxygen, creating new minerals. While oxygen is the most common element in the earth’s crust, most of it is bonded with silicates and oxide materials and is not free to act as a weathering agent. But when minerals are exposed to free O2 above ground, they undergo chemical weathering, that produces new minerals that are stable on the surface.  The most obvious example is when iron ions lose an electron with exposure to oxygen, rust is formed.

Bedding planes

bedding fold types: Caused by compressional stress. Although extensional stress is the major shaper of the Cote, there are some folds in the North-South direction, due to compressional stress.
bedding fold types: Caused by compressional stress. Although extensional stress is the major shaper of the Cote, there are some folds in the North-South direction, due to a compressional stress of bedding plates pushing against one another.

In many ways, I’ve put the cart before the horse by talking about the escarpment, before covering even more fundamental ideas. But that is how storytelling goes: sometimes you have to fill in the back story.

The world was a very different place 160 million years ago. This was five million years before the Allosaurus and Apatosaurus (formerly known as the Brontosaurus) roamed the earth. The limestone of the Côte, being a sedimentary material, was laid down in big, flat, shallow beds between the reef barrier that protected the lagoon, and the shore. Each layer was put down, one at a time, chronologically by age, marking millions of years. As the seas receded, and this is the main point, this would become a wide, flat valley of young, sedimentary limestone. It is likely that this bedding would eventually, be completely covered by wind-blown soils. We don’t know what happened to this young Burgundian stone in the intervening 130 million years between formation and the Fault Event, 35 million years ago, but it is unlikely it remained there unchanged. As geological stress acted upon the bedding, it would be pulled, pushed, deformed, and in all likelihood, in some way, fractured.

Author’s Note: For the remainder of this article, I will describe the stress and deformation, and potential fracturing of the stone in the body of the text, and in the photos I will show some of the results (that I am aware of), of that stress. Hopefully the two together will paint a complete picture.

It takes more than just ‘X’ to fracture

Bedding dips Bedding planes. All bedding started out horizontal, but through various stresses, the bedding planes often shift and compress one another causing folds or change their orientation.

Tilted Bedding Planes: While all sedimentary bedding was laid out horizontally, various stresses can shift the bedding planes into other orientations. Geologist measures the tilt by dip, the up/down angle, and strike the percentage off of an east-west axis.

I would love to be able to write that a particular limestone will fracture under the “X” conditions, but just doesn’t seem to be that simple. First, there are too many variables. How stone reacts to geological stress is directly related to its composition and construction as well as: its temperature, the amount of stress, multiplied by the duration of  stress. Most materials tend to be more elastic under higher temperatures and more brittle in low temperatures. It would be reasonable to assume that there was significantly more geological fracturing during ice ages because stone is more brittle in cold temperatures. At least in warmer temperatures, calcium carbonate stones tend to have good elasticity, depending on how pure their construction, as the chemical bonds in CO3 will move if pressure is applied very slowly. However, that elasticity is finite before the stone is structurally damaged as it passes its elastic limit; but more on that later.

Secondly, like I mentioned before, science cannot measure the stress, but rather the deformation due to the stress. For this geologists use a strainmeter, which they measure changes in the distance between two points. For greater distances technology has brought the laser interferometer. These tools allow the scientist to measure frequencies that represent deformation.  Over short periods of time, they record tides (I had never before considered the stress created by a 1.5 quintillion tons of water moving position above earth) and the seismic waves of earthquakes, while over longer periods of time, it can record the gradual accumulation of stress of rock formations.

The mission of this article? What I am looking for here, are some kind of answers these two questions: What conditions would make it possible for vine roots to bed into limestone bedrock? and What limestone types will fracture enough to allow this to happen? Anything learned along the way will be a bonus.

Stresses and the resulting strain

The ductile bending of this folded limestone was made under compressional stresses for a considerably long period of time. Ductile folds are not elasticity as, if released, this rock would not return to its original shape. Note the fractures that have developed almost vertically through the layers of stone.
The bending of this folded limestone was made under compressional stresses over a very long period of time. This stone. well beyond its elastic limit, has experienced a high degree of ductile strain, and is now brittle and structurally degraded. Note the fractures that have developed almost vertically through the layers of stone.

Stress causes strain of various types. Like I mentioned before, we are not able to measure the stress itself, rather only its effect by measuring the stone’s deformation. Below are the basic stresses upon objects and the resultant strains and deformations associated with them. Any deformation is considered flow (as science calls this) and it is domaine of an interdisciplinary study called Rheology. Here it is again, more simply, because its getting more complicated: Stress first.  It, in turn, causes strain. The result can be deformation, and this deformation is studied as if it were a liquid: as flow by Rheologists (a group of engineers, mathematicians, geologists, chemists, and physicists), who work together in an attempt to answer questions that transcend all of these disciplines.

6 Most Common Geologic Stresses (the first two are the most relevant to Burgundy)

  • Tensile, Tension, or extensional stress which stretch the rock or lengthen an object, will cause longitudinal or linear strain, and its effect is to lengthen an object, and can pull rocks apart. Like a rubber band pulled longitudinally, this is known as extensional rheology. As the rubber band breaks, that is called shearing flow. Rocks are significantly weaker in tension than in compression, so tensile fractures are very common. Tension stress formed the Côte d’Or.
  • Compressional stress that squeezes the rock and the resulting strain shortens an object. This too can be a linear or longitudinal strain. Stone under compressional stress can either fold (as in the photo to the right) or fault.
  • Normal Stress (can be either compressional or extensional) Normal stress that acts perpendicular to the stone.
  • Directed stress is typically a compressional stress, that comes from one direction with no perpendicular forces to counteract it. The higher the directed pressure the more deformation that occurs.
  • Lithostatic> and hydrostatic stresses are the compressional pressure of being underground or underwater. The force of the stress is uniform, causing compression from all sides.
This limestone jutting out of the vines in the Puligny vineyard, Les Combettes. Wine writers typically cite this common rock features as evidence of shallow soils, but these rock features are more likely a fold (plunging anticline) caused by compressional stress.
Wine writers typically cite these limestone outcroppings as evidence of shallow soil. But these rock features are more likely a fold (plunging anticline) caused by compressional stress. Location: Puligny, Les Combettes.

Interestingly, the effects of hydrostatic stresses upon an object are mitigated by oppositional forces. For example, the stress from below counteracts much of the force from above, and the forces from the right side counteracted by those from the left as they push against each other. So unlike directed stress, (the kind of stress that a 2 ton object exerts on top of a man), hydrostatic stress is like a scuba diver in the ocean. The stress of water upon the diver can be the same as the heavy weight upon the man, but because of counteracting stresses, strain is not expressed in the same way.

  • Shear stress is that which is parallel to an object. Shear strain (caused by shear stress) changes the angle of an object. It can cause slippage between two objects when the frictional resistance is exceeded, or even failure within an object. Faulting is an example of slippage under shear stress. I would be remiss to note that faults in Burgundy, at least to my anecdotal eye, often occur between limestone types.

 

Coaxial strain
Coaxial strain

 

The Magnitude of  Strain

Elastic strain and ductile deformation

stressesThere are two levels of strain. Elastic strain, in the effects of the strain, are reversible. The stone will change shape or deform under stress, with minimal damage to its structure, and then return to its original shape and position.

Ductile strain, is the area of strain once past the elastic level. The stone is now developing microscopic fissuring, and the stone can not return completely to its original size, shape, or position. Although the stone may not appear to be visibly damaged, any deformation into the ductile range, will harm the stone’ structural integrity. Additionally, in comparison to the deformation of the stone in the elastic range, the speed and ease of ductile deformation increases quickly (in structural geologic terms).  The deformation is now the result of micro-fissures that have emerged throughout the stone, and are now both propagating and enlarging. It is during this phase of rapid deformation that the stone can achieve dramatic folding from what had previously been flat, sedimentary stone.

By The Numbers: limestone limits

Elasticity in stone
Elasticity in stone

Author’s note: The measuring of deformation and the related stress involved becomes a bit more technical, and requires a number of lingo words to be used in the same sentence. I resist this as much as possible, because it requires the reader to be very familiar with the terms. Skip ahead if this doesn’t interest you, but it gives a numerical frame of reference for limestone fracturing.

The deformation under applied pressure is called flow, and the material’s resistance to deformation is measured (in newtons). The measurement of a stone’s elasticity is called it’s Elastic Modulus  (a.k.a. Young’s Modulus).

Elasticity of rock groups. Click to enlarge
The elasticity of rock groups. Click to enlarge

The Elastic Modulus measures the tensile elasticity, meaning when a material is pulled apart by extensional stress.  This resistance to deformation is expressed in gigapascals (GPa) which are one billion newtons per square meter. 

Additionally, there is Bulk Modulus, the measurement of a stone’s lithostatic (compressed from all sides) elasticity. This is expressed in Gigapascals, (GPa) or one million newton units.

And Shear Modulus, also known as the Modulus of Rigidity, in which the elasticity of a stone under shear forces is measured.  It is defined as “the ratio of shear stress to the displacement per unit sample length (shear strain)”.

Scarp Cutaway. Click to enlarge
Scarp Cutaway. Click to enlarge

I gave the MPa compressional strength (loads that tend to shorten) of various limestone types in part 1.1. Note here MPa is used, or one million newtons per square meter. The elastic modulus of most limestone can be as low as 3 GPa for very impure limestone (we don’t know what was sampled), and up to 55 GPa depending on purity of the calcium carbonate. As a comparison of elastic modulus: Dolomite (limestone with a magnesium component) typically ranges between 7 to 15 GPa, while Sandstone typically runs 10 to 20 GPa.

  • click to enlarge
    click to enlarge

    General Limestone Modulus Ranges (the range of deformation before fracture)

  • Elastic modulus range: 3 GPa – 80 GPa  
  • Bulk modulus range: 5 GPa – 66.67 GPa
  • Shear modulus range: 3.5 GPa to 33 GPa

 

The strain rate is important: which is expressed as elongation over time (e/t). The longer the period of time, the more the material can “adapt” to the strain. The faster the stress is applied exceeding the plastic elastic limit, the shorter the plastic region. The plastic region fracture where the material breaks and is considered brittle behavior.

  • Brittle materials can have either a small (or a large) region of elastic behavior, but only a small region of ductile behavior before they fracture.
  • Ductile materials have a small region of elastic behavior and a large region of ductile behavior before they fracture.

 

From Strain to Total Failure of Stone

The description of how stone reacts to crushing pressures reminds me of those submarine movies, where the hull is slowly being strained with a chorus of creepy groaning sounds, rivets popping and water spraying from leaks in the hull. In the laboratory, geologists study stones they crush, in order to understand what has occurred to rock materials over hundreds of thousands, to several million of years.

Infinitesimal strains refer to those that are small, a few percent or less, and is part of a mathematical approach material that is “assumed to be unchanged by the deformation” (Wikipedia).  As deformation increases, micro-cracks and pores in the stone are closed and depending on the orientation of the pores in relation to the direction of the stress, this can cause the stone to begin to deform in a coaxial manner. This non-linear deformation is obvious in weaker or more porous stone.

The goal is to explain how this happens in limestone with high calcium carbonate
The goal is to explain how this happens in limestone with high calcium carbonate content. photo alexgambal.com

While in the elastic region, stone adjusts to the pressure applied to it. Micro-cracks don’t appear in the stone until it reaches the 35%-40% way-point in elastic region. At this point structural strain is largely recoverable with little damage. At 80% of the elastic limit, micro cracks are developing independently of one another, and are evenly dispersed throughout the stone’s structure, despite the fact that the stone is at maximum compaction with no volume change. As the stone nears its elastic limit, micro-cracks are now appearing in clusters as the their growth accelerates in both speed and volume. The stones appearance and size remains intact as it passes its peak strength, although the structure is highly disrupted. The crack arrays fork and coalesce, as they begin to form tensile fractures or shear planes, depending on the strength” of the limestone.(1) The rock is now structurally failing, and considered to have undergone “strain softening”.  Additional strain will be concentrated on the most fractured, weakest segments of the stone, creating strain and shear planes in these specific zones, which as it nears the fracture point will essentially become two or more separate stones, ironically bound together only by frictional resistance and the stress that divided them. information source: Properties of Rock Materials, Chapter 4 p.4-5, (LMR) at the Swiss Federal Institute of Technology, Lausanne

The Bottom Line on the Fracturing of Limestone

Roche de Solutre and Vergisson, are large, tilted bedding planes. What little information that I have found of their formation (non-scientific) claims these are plateaus which raised when the Saone Valley was formed, and have later tilted to the East. Plateaus are often formed by magma pressure causing the ground swell upwards, or by glacial erosion. The theory that 400 meters of stone were reabsorbed back into the earth by tilting, sounds like sketchy science to me. I would consider a second option more likely: only one end of this structure was pushed above ground by geologic forces.
Roche de Solutre and Vergisson, are large, tilted bedding planes. What little information that I have found of their formation (non-scientific) claims these are plateaus which raised when the Saone Valley was formed, and then later “tilted” to the East.  The theory that 400 meters of stone were reabsorbed back into the earth by “tilting”, sounds like sketchy science to me. I would consider a second option more likely: only one end of this structure was pushed above ground by geologic forces.

The truth is that we don’t have any records detailing the condition of the limestone base that lies below the topsoil. Certainly the limestone base has been exposed often enough over the past century, that had some academic organization wanted to catalog this kind of information, there would now be a large database to refer to by now. Moreover this would be a substantial advance in the knowledge of how to farm these vineyards. Today, the most progressive vignerons are now making these inquiries themselves, digging trenches to find out what lies below in order to make the best replanting and farming decisions possible. But it is unlikely that even these recent efforts are being catalogued, as they investigated.

Vineyard Development: Limestone

Tilted bedding plane, whether a plateau as one source describes or not As a tilted bedding plane, The Roche (Roc) de Solutre and Vergisson, despite their distance South of the Cote de Nuits, and their slightly more youthful age, gives an unique glimpse into the layers of limestone in Burgundy. It reminds us, that whatever the top layer is, there lies different strata just below it. Click to enlarge
Tilted bedding plane, whether a plateau as one source describes or not
As a tilted bedding plane, The Roche (Roc) de Solutre and Vergisson, despite their distance South of the Cote de Nuits, and their slightly more youthful age, gives an unique glimpse into the layers of limestone in Burgundy. It reminds us, that whatever the top layer is, there lies different strata just below it. Click to enlarge

Limestone fracturing and shallow soiled vineyards

Since deeper soils do not require the vine to penetrate the bedrock in order to have a successful vineyard, fracturing there is not required for vineyard vitality.

However any vineyard where there is shallow soil, the limestone below must be compromised structurally, to some degree, for the vines to penetrate the stone. In this way, the vines themselves are a contributor to mechanical weathering of stone in the vineyards. Limestone varieties with a high percentage of impurities, are typically more easily fractured; although they may actually be soft enough, or porous enough stone for the vines to penetrate on their own.  It is documented that composite formations with heavy fossilization (like crinoidal), or clay content (like argillaceous limestone)  are less elastic than purer limestones with high levels of CaCO3, and are much more friable. You can read about limestone construction in Limestone: part 1.1.

With a harder stone, would significant ductile deformation with fissuring make the stone weak enough for the vine roots to penetrate?  Or does a limestone based vineyard need to be significantly fractured before vines can sufficiently take root? That answer to this question is not apparent with the information available at this time, but the answer is probably yes.

Mazy and Ruchottes Chambertin with dip and strike oriented faults. Significant outcropping has emerged from this hard Premeaux stone at the convergence of these faults. Interestingly its both parallel and perpendicular to the extensional, horizontal faulting
Mazy and Ruchottes Chambertin with dip and strike oriented faults. Significant outcropping has emerged from this hard Premeaux stone at the convergence of these faults. Interestingly its both parallel and perpendicular to the extensional, horizontal faulting

Vineyards like Mazy-Chambertin and Ruchottes-Chambertin give evidence that the more brittle Premeaux limestone (with its lower compressive strength, and higher porosity), if fractured enough, can support vineyards, despite there being very shallow topsoil. There are a number of linear, east-west oriented, limestone outcroppings in these two vineyards, indicating this area has seen significant compressional stress to the bedrock there over the last 35 million years, in addition to the tensile faulting caused by extensional stress that created the region. These two stresses would have created vertical dip joints, and horizontal, strike joints, and very possibly diagonal oblique joints, and fissuring in the bedrock. Enough for the vines to survive well enough for these two vineyards to be awarded grand cru status in the late 1930s.There has been a question in my mind whether Comblanchien, which is so dense that water cannot penetrate enough to effect freeze thawing, and is also very elastic due to its 98% calcium carbonate content, would fracture enough in a vineyard location to support a vineyard in shallow soils. In fact that has been a driving question throughout this piece, and which I was inclined to believe the answer was no, until evidence proved otherwise.  Apparently that has happened. 

The Rise of Colluvium

In terms of vineyard soil development itself, geologic pressures have worked extensively to prepare the limestone bedrock. Primarily with extensional stress, but also exerting compressional stress, the strain significantly weakened and fractured the limestone bedding. This deformation and the ensuing fracturing allowed water to infiltrate its cracks and crevices. During periods of cold weather it would freeze within the fissuring, causing frost wedging. Exfoliation would ensue, ultimately causing significant limestone debris to be pulled away by gravity, itself a powerful force of mechanical weathering, to slide (and tumble) down the hillside.  As the stones fell, they would further break and abrade into yet smaller pieces. Abrasion is another agent of weathering. There they would stop at the curb of the slope, where eventually they form deep, limestone-based “colluvium” soils. This is what Coates is speaking of when he wrote “rock and more limestone on the section closest to the over-hang, and there is some sand” in AmoureusesThese are the colluvium soils that would with enough time would generate the vineyards upon the the red grand cru vines of the Cote de Nuits would grow.

But first, the story of chemical weathering would have to play out, creating clay and soil needed to feed the vines. The slopes of the Cote d’Or would slowly evolve geologically for millions of years, awaiting the arrival Roman agriculturalists who would recognize and exploit the vinous wealth of this thin strip of the hillside.

Next up: Part 1.3 Amoureuses and Parallel Evidence of Shallow Soils over Comblanchien

 

Please feel free to comment, like, follow, share, or re-blog this or any of this terroir series!

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(1) Because it is often difficult to distinguish between the different types of fractures and  faulting once the fracture has occurred, I will leave it at this. There are 3 kinds of fractures born from the three major stresses: Shear, tensile, and extensional.

(2) I have not been able to determine if  crystallization is a definition of Comblanchien limestone, or if the Comblanchien limestone in the villages Corgoloin and Comblanchien just happen to have been metamorphosed into marble, and that is why it is quarried there.

Previous articles on Terroir

Limestone Construction: part 1.1 (click here)

Introduction to Terroir (click here)

Preface to my article on Terroir (click here)

Marl: The Most Misused and Misunderstood Word in Burgundy Literature? (click here)

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Understanding the Terroir of Burgundy Part 1.1 Limestone: formation

by Dean Alexander

Limestone Formation and Types

The Cote d'Or is the hanging wall of a faultline formed by
The Cote d’Or is the “footwall” of a fault line formed by the Saone Valley dropping away from the escarpment.

 

As the Burgundy legend has it, it is the limestone that sets Burgundy apart, and makes the wine that comes from there so special. But what does all of this limestone really do? Does it impart flavor, as some people say, imparting a minerality, or does it create a perfect growing condition for the vines? How does it interplay with what is possibly the most important component of farming, the clay, and what is its relationship with the limestone? Then there is the scree, or gravel, intermixing with what geologists sometimes refer to as colluvium. Together this makes soil, but how it got there, and how it is changing perhaps most important. The forces of erosion that constantly tear down the geological structures with its wind and rain and freezing temperatures. This is where the rubber meets the road of terroir, and I will look at all of these factors quite carefully over the next few writings. But first, for Part 1.1, it’s all about the formation and types of limestone that makes up the escarpment.

From the beginning

We typically think of hillsides as being pushed up, and indeed the hills of the Hautes-Cotes de Nuits were formed by folds in the sedimentary bedding. But the Cote itself was formed when the Sôane Valley was pulled down and away from the Côte d’Or  Burgundy 35 million years ago by a large fault that runs near the highway RN74, as the Saône Valley dropped away as a graben. The Côtes d’Or is actually the broken facewall of the horst. But before that, the story of Burgundy started with a sea, teeming with unbridled marine life.

ammonite
ammonite: courtesy of the Natural History Museum http://www.nhm.ac.uk

Just how much marine life has impacted this planet is represented by the vast majority of limestone formations that have grown here, constituting 10% of the total volume sedimentary rock, which represents 75% of all geological formations. Most limestone is credited to biologically produced calcium carbonate that is naturally extracted from eroding shells sea animals. Shell production, for defense against predators, began in the Cambrian period (500 million years ago.) This occurred with a change in the ocean chemistry which allowed the calcium compounds to become stable enough for allow for shell production. While at the same time (give or take a few million years), the animals adapted through mutation, to produce the needed proteins and polysaccharides, and the ability to produce shells for protection against predators. The success of this new animal life led to an explosion of species, and the warm shallow seas that covered central France were densely populated. The seas of the Jurassic period were filled with calcium producing crinoids, ammonites, oysters, and as corals. As the exoskeletons of generations dead sea creatures accumulated on the seabed, eroding, the waters filled with high concentrations of calcite and (or) metastable aragonite, (depending on the water chemistry of the period), where it precipitated into a thick, jelly-like solution at the bottom of calm lagoons and shallow seas. Eventually, this layer would solidify and compression would indurate (or harden) the (CaCO3) into limestone. Non-marine limestone is less common, with calcium being deposited in a location by the water, or calcium carbonate can accumulate at the bottom of lake beds, forming limestone.

Modern Crinoids are animals, organisms with a nervous system, and the larvae are capable of swimming freely before metamorphosing to the sessile form seen in this photo.
“…crinoids are animals, organisms with a nervous system, and the larvae are capable of swimming freely before metamorphosing to the sessile form seen in this photo.” http://www.mnh.si.edu/LivingFossils/crinoid1/htm

 

Calcium carbonate is soluble in groundwater containing relatively low acid levels and is responsible for the chemical weathering that forms limestone caverns and sinkholes. Interestingly, the calcium carbonate in limestone is more soluble in low-temperature environments than in warmer tropical climates that it began in. In a cycle that will likely continue during earth’s lifespan, limestone is formed, and then eroded (and been transported) by groundwater, to reform in another location. Limestones are sedimentary rock formations that contain at least 50% calcium carbonate in the form of calcite and or aragonite. The higher the percentage of calcium, the harder, the less porous, and more water-resistant the limestone becomes. Even the hardest limestone of Burgundy contain at least some silica, which after the chemical weathering of limestone becomes phyllosilicate minerals, the primary element in clay.  However, the higher the percentage of silica and other impurities renders a stone that is more porous and more easily friable (the ability to fracture or crumble) It is my belief that it was these impurities that have allowed Burgundy to become the great growing region it is today. Had all the limestone been the pure hard Comblanchien that the region is so famed for, I suspect there would not have been enough viable, arable land to have any significant grape growing area. But that is supposition on my part. Back to more fact-based information.

Comblanchien Limestone Quarry in the Cote de Nuits
Comblanchien Limestone Quarry in the Cote de Nuits

There are a number of common limestones in Burgundy, each which contain varying percentages of calcium and differing levels of impurities. The harder limestones are typically named after the towns that they were quarried for building materials, while softer, non-commercial limestones can be named for their fossilized sea life contained in them, or by the shape of their construction. Don’t be confused by names like Bajocian limestone and Bathonian limestone: these are not types of limestone, rather they are periods of time within the Jurassic when the limestone was formed. It is easy to be confused. I recently read this snippet from a knowledgeable, professional wine critic trying to explain the geological differences between the Côte de Beaune and Côte de Nuits. They wrote “…the Comblanchien limestone to the north and the Jurassic rock formation to the south…”  apparently unaware that Comblanchien is a limestone formed during the Jurassic period. I mention this only because it highlights the confusion even highest-level of wine professionals have about terroir and the geology of Burgundy.

Limestone Types (that you may read about)

Calcaire: The fact that English speaking wine writers use the word calcaire, is simply confusing to almost everyone trying to actually learn something. Calcaire is nothing more than the French word for Limestone.  We say limestone, they say calcaire.

comblanchien-limestone-
Comblanchien-limestone-

Comblanchien is a name bandied often by wine writers as if it is an attribute in a wine’s character. But the facts point to this stone having a negligible if any effect on the vines grown directly above it. Comblanchien is 99% pure calcium carbonate, often giving the stone a white color. As a building material that is commonly referred to as Comblanchien Marble. It is so dense and fine-grained that it can be polished. It can be white (clair), beige, or slightly pink.

Comblanchien formed from still water lagoons that were hyper-rich in calcium, and relatively void of sea creatures that would cause impurities. Presumably, the calcium solution was so concentrated that sea life did not live there, and generally did not disturb the (CaCO3) sludge in the areas where Comblanchien was forming. The spots in Comblanchien are not fossils or impurities, but the trails of worms that wiggled through the thickening lime ooze. The hole made by the passing worm was then filled by pure, clear calcium carbonate, and like a glue, it cemented the whole into a solid, amazingly dense block of stone.

Comblanchien Clair Limestone
Comblanchien Clair Limestone

Most defining in its role in terroir picture is Comblanchien’s exceptionally low-level of porosity. The stone virtually does not absorb water so it will not crack when frozen. Vine roots cannot penetrate Comblanchien if it has not already been fractured, which tends not to happen since it is so water-resistant. Where a vineyard grows over Comblanchien, (1) there is a need for a deep layer of topsoil for the vine roots to inhabit. Where Comblanchien reaches the surface at the top of the vineyards in the Gevrey-Chambertin, no vines are grown (or can grow?) A strata of Comblanchien sit at the top of the Côte de Nuits‘ vineyard as a cap rock, and it’s hardness and resistance to decomposition keeps the hill above from eroding. The result kept the depth of vineyards there, (this is particularly evident above the grand crus of Gevrey) in a very narrow band  An opposite example would be the Côte de Beaune. In Beaune the cap rock (if in fact there is one) is much softer. Because of that, the hillside is eroding at a much faster rate, a creating lower hill lines and much deeper (east to west) growing areas. Off topic, but not have to rehash this later, writers often contribute Beaune’s faster erosion rate to its younger limestone makeup (mid-Jurassic compared to upper-Jurassic which younger), but I believe it is the impurities or the porosity of the limestone, not the age (curing) of the limestone, are the factors of its faster erosion.

Comblanchien technical statistics: Water Absorption:% 0.49  Compressive Strength: 160.0 – 203.4 MPa (Comblanchien Clair: compressive strength 203MPa)  Density:2660 kg/m3

 

Rose de Premeaux
Rose de Premeaux Limestone

Premeaux is another hard limestone used in construction, but it is not quite as hard as Comblanchien. I have not found any reference as to how much calcium carbonate is in Premeaux Limestone, but as evidenced in this photo, it does crack and fracture. This is due to the fact that it will absorb 12 to 18 times more water than Comblanchien, which when permeated, then frozen, will crack stone. Premeaux, unlike Comblanchien limestone, is found at very shallow depth under vineyard land, most notably the Grand Crus of Ruchottes and Mazy-Chambertin, where in places the vineyard was dynamited in order to allow the plants to gain a foothold.

Premeaux technical statisticsWater Absorption: 6-9 By Vol.%  Compressive Strength: 120-180 MPa  Density:2400 – 2500 kg/m3

 

Crinoidal Limestone
Crinoidal Limestone

Crinoidal Limestone is closely associated with the Bajocian period and is named for the Crinoids that team its construction. Crinoids are multi-armed sea creatures that are filter feeders. Anemones, starfish, and urchins are among the 600 species of Crinoids found in today’s seas, but during the middle Jurassic there were many times more species, and they densely populated the shallow lagoons of Burgundy. Crinoidal limestone is friable, meaning it can be broken or crumble, because of its heavy fossilization. The hillside of premier crus, including Lavaux, Estournelles and Clos St Jacques in Gevrey-Chambertin is entirely made of crinoidal limestone. This formation continues above the Route de Grand Crus, underneath Chapelle, Griotte, Latricieres,  Charmes-Chambertin, as well as the lower half of Chambertin itself and Clos de Beze. To my mind, this is ample evidence that Crinoidal limestone is one of, if not the finest limestone for growing vines.

 

A close-up of Oolitic Limestone, which composed of tiny spherical ooids bonded by a calcium secretion.
A close-up of Oolitic Limestone, which composed of tiny spherical ooids bonded by a calcium secretion.

Oolitic Limestone formations are unique and fascinating composition. Oolites are formed of oval calcium pellets called ooids that gained their shape as they were rolled around by the wave actions the ancient Burgundian seas of the Jurassic that are super-saturated with calcium carbonate. The ooid spheres begin with as a seed, such as a very small shell fragment, and as this seed rolls around the ocean floor, it chemically attracts layers of calcium to it from the water. The size of the individual oodid corresponds to the amount of time they had to form before they were covered by dirt. While the word ooid typically refers to forms made from calcium carbonate and aragonite, the name means egg so the name ooids can be used to refer to other materials in the same small oval shape. These ooids bonded under a secretion of a calcium cement forming the stone. The grand cru Ruchottes-Chambertin is famous for the ooids found it its topsoil, and presumably oolitic limestone formations are there also along with the more prevalent Premeaux limestone.

Nantoux is an oolitic limestone is named by the late geologist James E. Wilson as being the stone that was once quarried in and above Meursault- Les Perrieres. Named after a village nestled in a valley above Pommard, it appears on Vannier Petit’s Pommard map, just north of the village, very low on the slope. She labels it as an oolitic stone, Wilson gave no details of the stone other than its former quarry location. I have seen no other reference to Nantoux other than these two brief references.

Argillaceous Limestone
Argillaceous Limestone is at least 50 percent co3, with the balance being clay. A very soft stone. Perhaps the perfect limestone for vineyards?

Other limestone types that rarely, if ever, appear in writings. Of the more common: Chassagne and Ladoix both appear on Francoise Vannier-Petit’s Pommard map, but there is little reference to them elsewhere. Both stones are available commercially as building materials, and both stones have pages dedicated to them on the Contactstone.com website, listing these stones density, strength, and water absorption similar to that of Comblanchien. However, they list Ladoix being an alternate name for Comblanchien limestone (as well as an alternate name for Corton Limestone), so it is not clear what the differences actually are at the geological level.

Argillaceous Limestone consists of larger amounts of clay, often making them quite soft and friable. In many ways, it is like a hardened version of marl. The stone may appear silvery due to the substantial amount of clay component. The vineyards of Chambertin and Clos des Beze both have sections in the heart of those vineyards that is made up of argillaceous material, as well as the lower third of Lavaux St-Jacques and Clos St-Jacques. Vannier-Petit labels these sections as Calcaires Argilleux (Hydraulique) on her Gevrey map which can be found at  www.joyaux-cotedenuits.fr/

Bioturbated Limestone
Bioturbated Limestone

Bioturbated Limestone is not actually a limestone but a disturbance to the forming stone that before it completely set. Whether calcium deposit was disturbed by an animal, a wave, or geologic action, churns the curing material. This agitation, or  Bioturbation, creates weakness in the limestone and can cause it to be quite friable depending on the impurities and the amount of disruption to its structure.

Travertine is not a maritime derived stone. It is a terrestrial calcium carbonate formation that is created by geothermally heated springs. Travertine is a very porous stone (that is filled and sealed by the stone industry for use in construction), and that porosity is caused either by calcium dioxide evasion or by organisms that have grown on the stone’s surface. As far as I am aware there are no Travertines in Burgundy.

Tufa is a calcium carbonate formation similar to Travertine, but Tufa is even more porous due to its large macro biological component. Tufa has no relation to the volcanic rock Tuff, which is often referred to as “tufa”. As far as I am aware there are no Tufas of either sort in Burgundy.

Marble is a limestone that has undergone a major geological event involving high pressure and or heat. In this process, limestone carbonate materials are recrystallized, very commonly calcite or dolomite. The colors in marbles are from the metamorphosed impurities in the stone that have become new minerals.

This hopefully gives a fairly detailed overview how limestone was created, and how susceptible it is to damage. In Part 2.2 I’ll look at how this limestone has been fractured and eroded, creating the basis for what would, over millions of years, become great vineyard land.

Up Next: Understanding the Terroir of Burgundy, Part 1.2  Limestone deformation and fracturing. (click here)

Previous: Understanding the Terroir of Burgundy, Introduction (click here)

Understanding the Terroir of Burgundy, Preface (click here)

 

Please feel free to like, share or reblog, any part, or all of these Terroir articles.

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(1) This is suggested by examining the geological vineyard mapping, recently published by the geologist Francoise Vannier-Petit.

* Calcium bicarbonate is what forms stalactites and stalagmites in caves and caverns.

2011 Joseph Roty, Gevrey-Chambertin, “Champs-Chenys”

Champs ChenysChamps-Chenys is one of those vineyards that was given a short shrift when the official INAO classification occurred in 1936. While the vineyard just at its hip (the lower section of Mazoyères-Chambertin*) is classified as Grand Cru, Champs-Chenys was only classified as a village-level wine. At first blush, the two vineyard sections look like a mirrored image of one another. Both vineyards hold the same position and exposition on the hillside. Both vineyards sit above the same Comblanchien limestone. But the difference between Mazoyères (bas) and Champs-Chenys is that Mazoyères sits in richer, sedimentary soils, that over centuries have washed down from a small combe, or ravine, cut into the hill above. This gives the wine from Mazoyères significantly more depth, power, and authority than a wine from Champs-Chenys can, with its limestone-rich marl that is covered with pebbles and galets and sprinkled with pyrite.

Immediately above Champs-Chenys is the Grand Cru “au Charmes” which is more commonly known as Charmes-Chambertin. Charmes has a marl topsoil like Champs-Chenys, but under that lies Premeaux limestone which is more friable than the Comblanchien below Champs-Chenys, so the vine’s roots are better able to penetrate deep into the stone below. Charmes is also warmer with the vineyard being tilted on the hillside toward the sun, and better protected from the wind, being tucked behind the hill. Charmes is well known for its delicate fragrance and rich, seductive fruit, and round smooth mouthfeel.

“This is a wine that is prized by cognoscenti of Burgundy’s finest, yet most under-appreciated vineyards.”

 

Aviary Photo_130556986614926167While all of this side by comparison to Mazoyères and Charmes point to Champs-Chenys being a lesser wine, it is actually very good news for those who realize what a solid vineyard Champs-Chenys actually is…  not to mention what a value it is (in terms of Burgundy) due to its simple village classification.  Additionally, Chez Roty’s parcel of vines is north of 50 years old, and the old plant material, coupled with Philippe Roty‘s considerable winemaking skill, leaves you with a wine that is routinely superb in quality. This is a wine that is prized by cognoscenti of Burgundy’s finest, yet most under-appreciated vineyards.  Roty’s lieu-dits of Champs-Chenys is without a doubt premier cru quality, and it can age effortlessly for decades.

photo 22011 Joseph Roty, Gevrey-Chambertin “Champs-Chenys”

The 2011 is just now coming out of what I felt was a considerable shock after shipping. A full 5 months after arrival, (Roty releases a year later than most other producers,) this Champs-Chenys is displaying this parcel’s distinctive smoky and savage aromas. It is the only cuvee in Roty’s line-up possesses these decidedly meaty smoky traits, indicating it is not the winemaking style rather the plot dictates the wine’s profile.  Although it drank well from the first moment, it really developed beautiful nuance over the course of a day, unfurling notes of roses, blood-like iron aromas underbrush, loam, blackberry and black cherry fruit.

After about an hour, it began showing the exotic, smoky, wild game-tinged aromas I expect to see from Roty’s Champs-Chenys.  The wine is round and quite fresh, and though not as powerful as bigger vintages, this does not lack for concentration. It has good structure, round tannins, and relatively soft acidity, making this a pleasure to drink now. The overall effect is a black-fruited, mid-weight Gevrey that is ripe, but without heaviness, nor is there any sur-maturity. It has excellent fresh fruit character of black cherry fruit that keeps it lively and long. The tannins are fine-grained and the finish that resonates long, and with nice complexity, all of which is highlighted by a deftly handled use of barrique. This a beautiful wine that will keep developing with age, but drinks beautifully now. 90 points when first opened.  92+ points when given time to open up. Very Highly Recommended.  $70

 

*Mazoyères-au Charmes can legally be, and usually, is labeled as Charmes Chambertin. This is because Charmes is a much more recognized name, making it easier to sell. Roughly 10% the wine make from this vineyard is labeled as Mazoyères-Chambertin

2012 Fredreric Esmonin, Gevrey-Chambertin, Clos Prieur

Clos Prieur Bas, with Clos Prieur 1er Cru and Mazis Chambertin directly behind it.
Clos Prieur Bas Vineyard, with Clos Prieur 1er Cru, Mazis Chambertin and the legendary Clos de Beze directly behind it.

Domaine Frederic Esmonin, a firm that produces solid wines from their cellar in Gevrey-Chambertin every year, really made some special Burgundies in 2012. The wines retain Esmonin’s characteristic freshness while gaining a touch more swagger, with modest but noticeable increases in ripeness, concentration, and depth. This is not to say these 2012s are big or heavy wines. They are not, but many crus could use a few years in the cellar.  Having tasted through the entire lineup at our San Francisco Tasting in April, the Clos Prieur was the one wine that was lighter, and quite a bit more aromatic than all of the others.

For me, Clos Prieur was a standout. It had such superb balance, and the aromatics melded seamlessly with its broad red cherry-filled palate while retaining an almost airy weight, all of which struck just the right cord. Whereas the other Gevreys were dark, impressive and somewhat brooding, the Clos Prieur was translucent and open. It is said by some winemakers that these vineyards just south of the village are prone to lightness and delicacy and that if care is not taken can be light and washed out if yields are not kept in check.

The grapes at Esmonin grown lutte-raisonnee. They are said to be destemmed, though I have detected what I believe to be the presence of at least some stems in the cuverie on more than one occasion. The fruit is cold-macerated for a few days, giving them the wines their dark color, before fermenting traditionally. The wines are bottled quite early, giving them a uniquely fresh, almost grapey quality when they are young. Andre Esmonin, Frederic’s father, makes the wine here. I reviewed the delicious, and darker 2012 Esmonin Hautes-Cotes de Nuits earlier this year. See that review here.

Clos Prieur Bas in the center of the map sits in deep marl (loose, earthy deposits that are a mixture of clay and calcium carbonate) over a Combanchien Limestone base.
Clos Prieur Bas in the center of the map sits in deep marl (loose, earthy deposits that are a mixture of clay and calcium carbonate) over a Combanchien Limestone base.

2012 Gevrey-Chambertin Clos Prieur 

This Clos Prieur is just lovely. A translucent ruby-red, this Pinot is all about purity, a quality that not celebrated often enough, and because of that occurs all too rarely in wine. The nose is fresh and buoyant, with cherries, smoke, a touch of thyme, vanilla, and some of Gevrey’s iron-rich meaty notes, along with a light airy quality of fresh roses. Initially, the wine appears lean, but as the palate adjusts, this gives way quickly to a soft round palate that is light and lovely. It’s rose-tinged flavors of cherry, deeper plum, orange peel, vanilla, and cream with a touch of stem, are perfumed and lifted,  just floating on and on. If you look for that animal, it is there, but not so apparent at this stage. I’m assuming this will become more prominent as it ages. This is not a wine and wine style people will accept as being a high scoring wine, but I have to say I really, really enjoyed this. Some have said this to be a bit simple, but I did not find that to be the case. It just wasn’t big and powerful.  Is there a confusion about what complexity is? The future for this wine is that it is destined to change; I think fairly dramatically. I may gain some more weight, and its freshness will certainly replace the more typical Gevrey traits of forest floor and savage animal notes, on it’s very aromatically driven platform. Esmonin’s wines are noted for how effortlessly they age, and this should be no different.  91 points (but I really liked it more than that).

Map produced by geologist Franciose Vannier-Petit for the Gevrey Chambertin Viticultural Society
Map produced by geologist Franciose Vannier-Petit for the Gevrey-Chambertin Viticultural Society

The Vineyard and the Geology

Clos Prieur is the name of two distinctly different vineyards. Despite this, writers have historically referred to them as a single vineyard that is split by classification. The Clos Prieur-Bas section, where this plot is located, sits down-slope, with much deeper marl topsoil, than its sibling. The bottom of Clos Prieur-bas is even more fertile, affected by the alluvial soil that was washed down from the Combe de Lavaux over the centuries.  Beneath the vineyard, virtually impervious to the penetration by the roots of vines, lies the very hard, fine-grained Comblanchien limestone.

On the other hand, the smaller premier cru of Clos Prieur-Haut, which sits atop Clos Prieur-Bas like a mignon, has shallower marl soils and the friable Crinoidal Limestone below. The very bottom of the vineyard is similar soils and Comblanchien to Clos Prieur bas, but it is amazing how closely these ancient vineyard divisions echoed the geology that had not been mapped until very recently. We can thank geologist Francoise Vannier-Petit and the Syndicat Viticole de Gevrey-Chambertin for this in-depth, (literally hundreds of investigative trenches were dug) in order to deliver this ground-breaking research. (I was unable to resist the pun.)

Notably, the premier cru of Clos Prieur sits among a string of premier cru and grand cru vineyards, including Chapelle, Griotte and Charmes-Chambertin, All which follow the same swath of Crinoidal limestone that runs North-South from Gevrey to Morey-St-Denis – and probably doesn’t stop there! This crinoidal limestone flows below the road (the Route de Grand Crus) which is the upper-most boundary of  Clos Prieur-Haut and is no more than 200 yards wide at this point. The Crinoidal limestone widens as it reaches the Clos-de-Beze vineyard, coving half of that cru and half of Chambertin as well. While the road turns away from its path along the limestone toward N74, the line demarcating vineyards continues to follow limestone below.