Understanding the Terroir of Burgundy: Part 3.4 The Grand Crus

 By Dean Alexander

While working my first wine shop job twenty years ago, I asked the store manager – who was a Burgundy guy of significant reputation: “Why is Rousseau’s Ruchottes-Chambertin not as good as his Clos de Bèze and Chambertin?”  The answer I got was honest: “I don’t know. I’ll have to ask next time I’m there.”

Years later that realized that I had asked the wrong question. The question I should have asked was this: What causes these neighboring vineyards to produce wines of such different character? 

Today, twenty years later, I can answer that question. If you have read my previous 12 articles in this series on Understanding the Terroir of Burgundy, it is likely you can answer it too. More importantly, some of the lessons here can be used to understand other appellations where less concrete information is known.

Clos des Ruchottes to the right, and Ruchottes du bas, on the left. photo: googlemaps
Clos des Ruchottes to the right, and Ruchottes du bas, on the left. photo: googlemaps

The short answer

Chambertin, Chambertin-Clos de Bèze, and Ruchottes-Chambertin

These three grand cru vineyards sit in a row, shoulder to shoulder on the same hillside. All have their upper-most vines smack up against the forested hillside, and all have virtually the same exposition. The legendary domaine of Armand Rousseau farms and makes wine from all three of these vineyards; yet one, the cru of Ruchottes-Chambertin, does not seem to be cut from the same cloth. The wine made from Ruchottes is not as rich or opulent. It tends to be lighter, more fine-boned, and more angular in its structure. The primary reason for this difference in wine character is that right at the border of Clos de Bèze and Ruchottes, the limestone beneath changes significantly. Unlike the other two vineyards, Ruchottes-Chambertin sits over very hard and pure limestone that is composed of almost completely of calcium carbonates and very little in the way of impurities, such as mud or clay.

The impurities within the stone, (bonded by the calcite) is what determines how much clay and other materials will be left behind as bedding materials when the stone has weathered. The more impurities in the limestone, the more nutrients will be available for the vines when the stone weathers chemically.  Further, it will reflect not just how fractured the stone has become due to extensional stress, but it will have often been the determining factor of whether the bedding has become friable as well. The wines of Chambertin and Clos de Bèze have this sort of impure limestone as a bedding under three-quarters of its surface area. It is a significant factor in giving the wines of Chambertin and Clos de Bèze a heavier weight and richer character than the wines from Ruchottes.

Another major factor in this differential in wine weight is that Ruchottes is a much smaller appellation, which confines it solely to the upper slope. Its location makes it subject to all of the factors that challenge upper slope vineyards, details that are examined in Part 3.3.  Conversely, both Chambertin or Clos de Beze extend almost three times farther down the hill, all the way to the curb of the slope. Additionally, while the degree of slope may kick up in the upper final meters of the Clos de Bèze and Chambertin, the area under vine upon upper slope (that will produce a lighter wine) is relatively small compared to the entire surface area of those vineyards.  

Unlike Ruchottes, the long slopes of Chambertin and Clos de Bèze will reach down to almost to where the slope completely leveled off. There at the base of the slope, rock and soil colluvium will have been transported by gravitational erosion, adding generously to the depth the soil. This depth allows more water to be absorbed and retained for use by the vines. It is rich in limestone rubble, gravel, and catches and holds more fine earth fractions including transported clay that has flocculated there. Above ground, scree litters the vineyards

The fact that most ownership parcels run in vertical rows, from the top of the vineyard to the bottom, assures that any lighter, more finessed wines will contribute, but not dominate the overall blend. In other words, blending of heavier wines lower on the slope masks the lighter wines from the top of the slope. 

It is abundantly clear that the vines benefit from the higher levels of nutrients in these deeper soils. They develop grapes that carry more color (anthocyanins) and brings many times more dry extract to the wine. This translates as the wines of these vineyards having a richer, more velvety texture, increased depth, all of which covers the structure. On the opposite end of the spectrum, the upper-slope position of Ruchottes-Chambertin dictates that the soils there are very shallow, and while there is a high percentage of colluvium, it is not as rich in sand, silt or clay-sized particles.  In fact, there are places the topsoil has completely eroded away, leaving fractured stone and primary clay and marly-limestone between the voids and breaks in the rock.

New research allows new understanding

Today we can examine this variation of limestone within a vineyard with a precision that was not possible a decade ago. This is due to the groundbreaking work of geologist Françoise VannierPetit and her mapping of the dominant limestone beddings of Gevrey. Through her work, we know that Ruchottes is a very homogeneous terroir, one with a very pure and hard limestone bedding dominating the vineyard. While the stone does not provide much in the way of nutrients to nurture the vines, we know it is well-fractured by two large faults that run through the vineyard.  Because of the vigorous faulting and fracturing throughout the vineyard, Ruchottes does produce a grand cru class wine, but it is a grand cru of a different character.

The geological factors in Ruchottes do not typically produce a wine with the substantial fruit or thickness of a Chambertin, and this ‘reduced’ level fruit often does not completely ‘blanket’ of structure in the wines from Ruchottes. This obvious structure is often mentioned in wine reviews, noting heightened acids and tannins, lending the wines a more angular construction than in other grand crus. By the same token, the wine from Ruchottes is often quite aromatic, with finer bones, for this wine, it means exhibiting more finesse, as well as giving the taster a heightened awareness of the wine’s precise rendering of detail. In another vineyard, this might be attributed to the grapes achieving less phenolic maturity, but the wines of Ruchottes are ripe, they just aren’t typically as large scaled or heavy. Moreover, they can be remarkably beautiful wines that can age effortlessly, for decades; often gaining poise, polish, and balance while doing so.

The gentle slopes of Chambertin. Photo: googlemaps
The gentle slopes of Chambertin. Photo: googlemaps

The substrate of Chambertin and Clos de Bèze is much more varied. With Vannier-Petit’s mapping information, we know that 35 million years ago the vineyards of Chambertin and Clos de Bèze were opened up by a large fault. This exposed the older (2 million years +/-) of softer bedding planes below.  They are both divided by four bedding planes, three of them being of soft, friable, impure materials, giving excellent nutrients.  This softer, highly fractured bedding allows the vines to thrive, and produce wines with much higher levels of fruit. This is the heart of Chambertin and Clos de Bèze.

Additionally, the twin vineyards are perfectly situated, mostly upon a gentle gradient which will resist erosion, or better yet, at the curb of the slope, where the soil is deeper,  The vineyards are well protected from wind, being squarely behind the hillside of Montagne de Combe Grisard. These two vineyards sit in the sweet spot of the heat trap formed by the hyperbolic concave of the slope. This positioning allows ripening occur even in most cold, wet years. Ruchottes, while fairly well protected, it is nearer the Combe de Lavaux through which cooling winds flow down the vast gorge.

All of these factors make the wines made from Chambertin and Clos de Bèze much easier wines to understand because they have so much to give. They can be very seductive and complex and can be drunk either young or old.  Are they typically better wines than can be made in Ruchottes?  The knee-jerk reaction is yes, as Ruchottes can be equated to the man fighting with one hand tied behind his back. But when a well-made wine from Ruchottes is opened at the right time and served with the right meal, it can be perfection.

Armand Roussaux parcel map

Chambertin clos de Beze

 

Digging deeper 

Gevrey-Chambertin topography

Generally speaking, when compared to vineyards in some of the other villages, the grand vineyards of Gevrey are fairly mild in their gradient. The uppermost vineyard sites of the Chambertin-named vineyards butt up against the Montagne de Combe Grisard’s “chaumes” (or ‘scruff ‘ in English). But unlike the steep upper hillsides of Vosne or Volnay that were able to be planted to vine, there is an unarable, rocky, forested landscape. Here in the chaumes, where no vines are planted, the hillside above Gevrey becomes steep.

The premier cru of Bel-Air is the one real exception. Carved out of a void in the rocky forest, and perched directly above Chambertin Clos de Bèze, Bel Air is a steep vineyard. It is a superb example of the struggles upper-slope vineyards face. See Part 3.3.1 for more on this. According to Vannier-Petit, a white Oolite formation underlies the uppermost section of Bel Air, and Premeaux Limestone underlies the lower part. Several writers have described Clos de Bèze as having Oolite formations below the soils, but Vannier-Petit does not note this. Instead, it is likely that Oolite has slid, as scree, or even in large chunks as a rock slide, into Clos de Bèze, from Bel Air above.

A prominent feature of the area, as outlined by the late James E. Wilson, a geologist, and author of Terroir (1998), is a rocky outcropping he referred to as a “Comblanchien cap“. While this was not part of the vineyard landscape, he described it as a major feature of the “Nuits Strata Package.” This term,“Nuits Strata Package,” as coined by Wilson, is an overarching reference to the bands of limestone bedding that stretch from Marsannay to Nuits-St-George, a layering of limestones unique to the Côte de Nuits. An upper-band of Comblanchien stone, he wrote, formed a structural bulwark or ‘cap’ which has allowed the upper-hillside to resist erosion, while the softer center eroded more quickly. This has caused the Côte de Nuits to develop its hyperbolic concave slope-shape. This concave slope relief, as I wrote earlier, allows the heat of the sun is trapped, allowing fruit to ripen fully. This is particularly true for vineyards such as this that sit in a wind shadow which is created by the trees and hillside above.

Interestingly, a much more recent map of Gevrey by Vannier-Petit, does not deem it necessary to include hillside construction above the vineyards.  So while she shows no Comblanchien cap rock at the edge of the Gevrey’s vineyards, as it seems Wilson described them, she does shows that the Premeaux stone extends one hundred or so meters up-slope. This extends well beyond the farthest, uppermost edges of the vineyard land.  While she may have felt the composition was outside the scope of the project, certainly anything that will wash, slide, or roll into a vineyard, is of great importance to our understanding of the physical vineyard makeup.

Ruchottes-Chambertin: a largely homogeneous appellation 

Here, a photo by Armand Rousseau illustrating the lack of topsoil, and the width of the fractures in the Premeaux limestone. No doubt this is a more extreme section, but it gives us the understanding of the relationship between the hard stone, fracturing and the difficulty of dealing with erosion in these vineyards.
Here, a photo from Armand Rousseau illustrates the lack of topsoil and the width of the fractures in the Premeaux limestone. No doubt this is a more extreme section, but it gives us the understanding of the relationship between the hard stone, fracturing and the difficulty of dealing with erosion in these vineyards.

Ruchottes-Chambertin, and it’s ying-yang partner. Mazy-Chambertin (also spelled Mazis-Chambertin), sit at the tail end of the string of grand cru vineyards. The primary limestone beneath both vineyards is the significantly calcium-pure, Premeaux. Premeaux limestone, which is marketed as marble, is highly desirable for construction and prized for its pink color. It is very similar to Comblanchien (which is a creamy white), but slightly less pure, (hence the color), and slightly less resistant to geological strain. See Part 1.1 for detailed compressional strengths of various commercial limestones.

Technically, the Ruchottes appellation is made up of three small, roughly equally-sized vineyards:  Ruchottes Bas, (meaning the below) Ruchottes Hauts, (meaning above), and next to that, against the forested outcroppings at the top of the hill, Clos des Ruchottes. The Clos is a monopole owned by the firm of Armand Rousseau.

While the lower half of the Clos des Ruchottes shares the rest of Ruchottes’ Premeaux limestone, the uppermost section, is covered in a layer of white Oolitic stone. Oolitic stone is made up of millions of small, oval, carbonate Oolite (egg stone) pellets that are fused by mineral cement. This composite construction makes the stone more susceptible to fracture, and the vines find it far easier to penetrate the many weak spots in this more porous stone. If anything, this is a benefit that the Clos des Ruchottes has over the rest of the Ruchottes appellation, especially since it is so high upon the hill. However we don’t know if the Oolite is of significant depth, and it is likely that Premeaux lies directly beneath it anyway. In either case, as vineyards go, the entire appellation of Ruchottes-Chambertin, is remarkably homogeneous in character.

The excellent Armand Rousseau website discusses Ruchottes Oolitic limestone, as well as shows the firm’s holdings in the vineyard, and is fairly detailed, and seemingly competent in their geological explanations, a surprising rarity in Burgundian marketing. Below is an excerpt.

The soil is composed of a shallow layer of red marl up to the top of the area. It is very pebbly, shallow and not fertile. The vines are based on oolithic limestone dating from Bathonien which disintegrates if frozen producing scree. This soil type forces the roots to go deeper into the rock. This results in a more fragrant, mineral style of wine that is lighter in colour but with a fine and elegant body. domaine-rousseau.com/en

Examining Ruchottes faulting and fracturing

We know through of the study of fracturing along the Arugot fault in the Dead Sea Basin, that as the distance from the fault increases, fracturing diminishes in frequency. This means that fracturing still occurs in its clusters, but the spacing between clusters is farther apart, leaving stretches of relatively undisturbed stone between areas of fracturing. As Ruchottes is located at the farthest possible distance in Gevrey from the main Saône fault, we rightly might expect this hard stone to be only intermittently fractured. Certainly, there have been numerous accounts over the past century of vignerons having to dynamite sections of these vineyards to break up the stone enough to plant their vines.

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

Unknown before Vannier-Petit’s work were the locations of sub-faulting that occurred at the same time that the Saône Fault developed.(1) Two sub-faults bi-sect Ruchottes and Mazy, right at the border with Clos de Bèze. The vertical fault-line follows the boundary between the Premeaux stone and the various beddings that make up Clos de Bèze.

Ruchottes origin during of the Côte’s creation 

The once level Premeaux limestone bedding of Ruchottes came under great strain as the land that now forms the Saône Valley Basin pulled away and began its slide down. As the limestone slab was pulled extensionally, the once solid piece of limestone bedding first began to microfracture, then to fracture throughout the body of the stone. As understood by the study of fluid mechanics, stress intensifies exponentially upon weakest areas of the stone, from which fracturing propagates, until the main horizontal break, or fault occurs.

As this faulting occurred, the neighboring blocks of limestone were pulled downward by the void made by the dropping/falling off the fledgling Saône Valley. As this happened, bedding of Ruchottes began to tilt and slide downwards, both pulled and sliding with the adjacent formations. It is not clear if this was a rapid, cataclysmic event, or that it happened over the span of hundreds of thousands or even millions of years. Either way, the stress upon the Premeaux bedding of Ruchottes was extraordinary, and what fracturing that was not caused the faulting, certainly occurred as it tilted and moved its position downward.

Often times, faulting can cause one plate to sit significantly higher than the next, forming a drop off which may or may not fill with soil.  In some locations, such as the fault between Chevalier-Montrachet and Le Montrachet, this has occurred What soil was lost by Chevalier to erosion, found a fine resting place in Le Montrachet, allowing the soils of Le Montrachet to become much deeper (and richer).  In other instances, erosion may once again level any difference in bedding height created by faulting. Alternately, the bedding may remain at the same height following the fault creation.  To the best of my knowledge, any height differential between Ruchottes du bas and Mazy Hauts is not documented.

Looking at the satellite image, there are certainly several visual clues that this faulting exists. Most obvious are the signs of significant stress are the limestone ridges, where the bedding has folded upon itself, that pushed above the topsoil. These are the dominant features directly above the southern end of Mazy Haut, and just like the walls of Clos, these limestone ridges greatly reduce erosion in these areas, which results in deeper richer soils and thus weightier wines, not only in Mazy but in that area of Ruchottes du Dessus.

Clos de Beze & Chambertin: four distinct bedding planes

Here the soft friable makeup explains the ease that the vines have in extracting nutrients and water from the base rock
Here the soft friable makeup explains the ease that the vines have in extracting nutrients and water from the base rock

While Chambertin and Chambertin Clos de Bèze are very similar to each other, they are unique to all other vineyards in Gevrey. Both vineyards share the same four bands of bedding planes, in roughly the same proportions. The one largest difference between them is that there is a higher percentage of Crinoidal stone in Clos de Bèze than exists in the northern end of Chambertin.  However, what is farmed depends completely on the parcels owned, not what exists in the vineyard itself.  It is increasingly clear is that a parcel is a vineyard in itself, and sections within parcels can hold wide variation in the character of wine it will produce.

Upper-slope Bathonian beddings:

Premeaux limestone and Argillaceous limestone/Shaley limestone

The uppermost sections of both Clos de Bèze and Chambertin sit over the very pure, and hard, Premeaux limestone, formed during the Bathonian which is a 2 million year period of the upper middle Jurassic. As in Ruchottes, we can expect this Premeaux limestone to be fairly well-fragmented. If this were the only stone found below the surface of these vineyards, the wines would taste much more like Ruchottes, but that is not the case.

The middle-upper section of these sibling vineyards is argillaceous limestone. This is a calcium-rich clay matrix may be indurated into stone, or it also may be soft and more marly. The clay, or argile as it is called in French, normally composes up to 50% the matrix, with roughly the balance being calcium carbonate and impurities. To this Vannier-Petit adds the word hydraulique, (in parenthesis), which refers to the fact that this particular limestone contains silica and alumina, that will yield a lime that will harden under water.  The assumption is that this Calcaire Argilleux formed underwater in the Jurassic lagoon or seashore, by secreting quicklime which bound with the clay, 168 million years ago.

Decanter Magazine alternately, and perhaps inaccurately, translates from the French Calcaire Argilleux, into Shaley Limestone, (as seen in the map box). That said, Françoise VannierPetit describes in an interview, that the relationship of clay and shale, is almost as one material that continually is in a transition from clay to shale – and back again, depending on how hardened (indurated) it becomes, or degraded. That stated, shale is generally regarded as lithified clay mixed with silt, the blend of which causes the notable horizontal striations, while a body of transported clay (of a single type, ie. Kaolin) that has been indurated (hardened) is termed claystone. Geologists are notorious for their loose use of terms, which makes it challenging for the rest of us to catch up, and I suspect Vannier-Petit is often guilty of this. AC Shelly is credited with writing in 1988 that “The term shale, however, could perhaps be usefully abandoned by geologists, except when communicating to engineers or management‟

Nothing is as simple as a name. Shale can be found in many forms. The relationship between clay and shale is very tight, just like water and ice.
Nothing is as simple as a name. Shale can be found in many forms. The relationship between clay and shale is very tight, just like water and ice.

Middle to lower slope Bajonien beddings: 

Marnes à Ostrea acuminata & Crinoidal Limestone

The oyster, and other fossils that sedimentologists are constantly mentioning as being present the bedding is really only relevant because it allows the scientist to easily reference age of the material. The fact certain creatures lived only during distinct periods of time, and only in certain environments. So not only does it give scientists the age of the strata, but it tells them a lot about the particular conditions that existed in that location, quickly allows the scientist to assign the formation of the bedding material to a particular period of time. As the fossils display different signs of evolution, (in the case some oysters, their valve position changed over long periods of time) the sedimentologist can establish the age bedding, and allow them to recognize a change of bedding (at on the surface) simply by the fossils in each location.

Using this methodology, the scientist gleans information about how the bedding has shifted position or even its location. These shifts have been very significant in the Côte. By categorizing strata by type, and fossil type. and date, they can match one stratum in one location with its mate in another.  This methodology allows sedimentologists to correlate strata worldwide.

Oyster bedIn the vineyard of Chambertin, the marl (Marnes à Ostrea acuminata) lies in a layer just beneath the argillaceous material that once was an ancient oyster bed. It is loaded with fossilized oyster shells (Ostrea)  from the upperBajocien period. This soil, into which the fossils are bedded, contains a large amount of the clay, montmorillonite, which has a very high cation exchange rate, and such soils, with their negative charge, attract and hold positively charged ions called cations (minerals like calcium (Ca++), magnesium (Mg++), potassium (K+), ammonium (NH4+), hydrogen (H+) and sodium (Na+) that are crucial for plant growth. This makes this particular marl which lies in the heart of Chambertin, a particularly sweet spot for vines. And because this is a bedding plane that underlies the Argillaceous material above it, those vines whose roots can reach that deeply may benefit from the Marnes à Ostrea acuminata too. That said, the deeper roots, it is reported, do not typically supply vines significantly with nutrients, that vines rely on their shallower root systems for this function.

gevrey pre slideThe age of the Marnes à Ostrea acuminata dates back to the very late Bajocian, parkinsoni zone 168.3 +/-, well before the Premeaux which lies above it was formed on top of it. This important because this decisively shows that the Comblanchien bedding, which lies at the base of the hillside (and was formed later in the Bathonian), slid downslope,  pulled eastward with the falling Saône Valley. This slide of this sheet of Comblanchien bedding plane, which at one time overlaid the argillaceous and oyster marl material and lay next to the Premeaux, moved downward almost 100 meters and eastward by roughly 200 meters. This left expose this older argillaceous marl and crinoidal bedding to the air for the first time after having been buried for the previous 133 million years. The next bedding plane is the also Bajocien in origin, again being older than the Premeaux higher on the hill, and older than the Comblanchien which sits below both Chambertin and Clos de Beze.

The lowest section of Chambertin and the largest percentage of Clos de Beze’s acreage consists of the well-fractured Crinoidal Limestone. This is the most common base rock upon which, the classified crus of Gevrey are planted.

Crinoids were extremely prevalent the lagoons and Jurassic seas worldwide, until the Permo-Triassic extinction when they were virtually wiped off of the geologic record. Their fossilized remains create weakness in the stone that encases them. This weakness in the stone, coupled with the geological fracturing of the area, has made it relatively easy for the vine’s roots to penetrate deep into this rock strata. Impurities in the stone’s construction, allows for chemical weathering, brought about by rainwater infiltration, to create rich primary clay bedding for the vines, within the breaks and gaps in the rock. These factors have proved that Crinoidal limestone provides a very effective and fertile bedding for Pinot Noir to grow.

Wilson described the Crinoidal limestone as being “cracked by numerous small faults which ‘shuffle the cards’ of strata, but generally are not large enough to ‘cut the deck’ to introduce markedly new strata.” Terroir (1998) p.131.  This is typical of his breezy style, and while it is visual (in terms of cards), it really doesn’t have much concrete meaning, other than being a colorful way to say the crinoidal stone is well-fractured. He does go on to say that this extensive fracturing allows the stone to be a good aquifer for the vines.

crinoids

Colluvium: atop the bedding planes

Almost every grand cru vineyard in the Côte de Nuits has significant amounts of colluvium mixed in their soils. While Ruchottes-Chambertin does have colluvium is one of the most glaring exceptions it is not significant in quantity.  Typically, this colluvium is accompanied by a fair amount of transported clay, which when together often forms marl.(2)  Rarely does one exist without the other in vineyards that have been classified as grand cru.

In the Côte de Nuits, there tends to be more colluvium in the colluvium to clay matrix, while in the Côte de Beaune, there tends to be more clay.  This tends to the case because there are many more marl bedding planes in the Côte de Beaune than there are in the Côte de Nuits, where marl bedding is rarer. There may be more shale in the Côte de Beaune as well.

 

The tête de cru, –  the very finest of the grand cru vineyards, have relatively equal proportions of marl and colluvium and sit only upon the slightest of slopes. This applies to the vast majority of Chambertin and Clos de Bèze vineyard area. These crus possess a perfect planting bed for vines: they have colluvium/marl based topsoil that is at least 50 cm (19 inches) deep where the absorbing roots are active.(3)  Because of this construction, the soil has good porosity for root and water infiltration but is not so porous a material that the water does not drain right through it, or cause it evaporates quickly from it. Additionally, because of its rocky nature, the grand cru soils tend to resists compaction.

While there is a band of harder, less fertile Premeaux stone on the uppermost slopes of Chambertin and Clos de Bèze, this represents a minority proportion of these vineyards. Parcels that have vines on these upper slopes, often lend a measure of finesse to the finished wine, without impacting the palate impression of the finished blend. For these reasons, Chambertin and Chambertin Clos de Bèze are among the finest vineyards in the Côte de Nuits.

Clos des Ruchottes, (and Ruchottes in general) is a far different vineyard than its two neighbors. With the near-pure calcium stone beneath its shallow soils, the low levels of impurities mean that when it weathers,  very little clay is produced. Because of the scant soil, the vineyard their neither contains nor can it attract, as much in the way of nutrients for the vines as can Clos de Bèze with which it shares a border. The resulting wines typically have less fruit, less color, seem more structured or tannic, and have a finer, though thinner texture. On the upside, the vineyard produces a very classy wine that can have excellent aromatics, remarkable finesse, and has excellent age ability.

Agree? Disagree? Comments are welcome and encouraged! Please feel free to like or share this, or any other article in this series!


Note: Many authors note that Clos de Bèze has Oolitic limestone. Vannier-Petit does not note this on her map. Instead, she places the Oolitic stone in the premier cru of Bel Air, which sits directly above it. A likely explanation of Oolite being cited as existing in Chambertin is scree/colluvium from Bel Air has slid down, to litter Clos de Bèze from above.

(1) The problem with always talking about the Saône Fault ignores the fact that the fault is really the most minor part of the geological event that happened. It was a continent being pulled apart which caused the void into which the entire region from the Côte d’Or to the Jura fell into a trough which now forms the Saône Valley. The Saône Fault is nothing more than as scar marking that event. And in fact, the Saône Fault lies buried quite deeply underground – its general location is only estimated.

(2) Marl would require a smaller particle size than just rock and gravel-sized limestone pieces to produce the non-clayey consistency that marl displays.

(3) Despite the conventional wisdom to the contrary, it is this shallow absorbing root system that gathers the majority of nutrients that vines require.

 

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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 2.2: Soil formation

We all know what soil is, or at least we think we do. If I were to ask you what was in soil, what would you say?

by Dean Alexander

In healthy soils, minerals typically only represent slightly less than half of the volume of soil, while air and water incredibly represent much of the rest. Here is the soil of La Tache in Vosne Romanee.  photo: leonfemfert.wordpress.com

Soil: 45, 25, and 25%

Despite all the talk about limestone, to really understand the terroir of Burgundy, we really have to understand what soil is and the material from which it is eroded. The mineral component, or the part we think routinely of as soil, are typically only 45% of the soil matrix. The balance is actually 25% air, and a further 25% of water, with the last 5% being split between humus (4%), roots (.05% ), and organisms (.05). It would make sense that this percentage changes seasonally, depending on how much water is in the soil from rainfall (or the lack of it) which changes the ratio of minerals, water, and air. Further, these ratios can change based on soil compaction, which decreases the air in the soil, which in turn increases the percentage of the mineral and organic component.  Why is this important? Because this is the environment that the vines live and they require a certain ratio of each of these components to produce high-quality grapes.

Cote soil influencers
I developed this graphic to illustrate the assorted soil formation processes that affect the Côte, and are described in depth in Limestone Fracturing in Part 1.2, and from Limestone to Clay in part 2.1, in earlier articles in this series. This article, Part 2.2 Soil Formation, builds upon those earlier concepts.

 The 45%: Burgundy’s mineral makeup

The French refer to the loamy Saône Valley fill as Marne des Bresse. The earth there is very deep, and typically is too wet for high-quality grape production. Historically this been used for pasture land for sheep and cattle. With every storm, this rich loam from the valley intermixes a little bit more with the soils of the boundary vineyards, and even encroaches on the loose, stony soils of the Côtes lower slopes.  ‘Interfingering’, was how geologist James E. Wilson described this mixing of soils in his 1990 book, Terroir: The Role of Geology, Climate, and Culture in the Making of French Wines.

Bore samples, according to Wilson, had indicated that this interfingering has reached westward, up the hill, to influence the soil construction of the lower sections of the grand cru Batard-Montrachet. With this information, he inferred that the Saône fault must be near.  It is notable that in 1990 precise location Saône fault was not known, and around Puligny, it still may not be. I suppose the wealthy Puligny vintners have no need to explain why Puligny-Montrachet is great. Vannier-Petit however, does tacitly show the Saône fault in her map of Gevrey, which is represented by the abrupt end of the limestone bedding east of RN74.

The ravine Combe de Lavaux defines character of most of the premier crus of Gevrey-Chambertin, but more importantly, its alluvial wash greatly expanded the growing area of vineyards below the village. Click to enlarge
The ravine Combe de Lavaux defines the character of most of the premier crus of Gevrey-Chambertin, but more importantly, its alluvial wash greatly expanded the growing area of vineyards below the village. Click to enlarge

Because the Côte is an exposure of previously buried, older limestone, younger soils line the divide on either side of the escarpment. The Saône Valley’s Marnes de Bresse brackets the Côte on the eastern, lower side of the slope, while younger rock and soil material that cover the tops of the hills, to the west, and beyond.

From the hilltops above, those younger soils have eroded down, bringing feldspar and quartz sand, silt, as well as phyllosilicate clay minerals, to help fill in and strengthen the rocky limestone soils of the Côte. In many places, geological faulting, coupled with runoff or streams, have created combes or ravines which have allowed substantial alluvial washes to extend the planting area of the Côte. A prime example of this is the Combe de Lavaux which is a dominate feature of the appellation of Gevrey-Chambertin.  It has sent a large amount of alluvial material around and below the village of Gevrey, creating good planting beds for village-level vineyards. Alluvial soils are nothing more than a loose assortment of uncemented of soil materials that have been transported by rain or river water. These materials are typically sand, silt, and clay, and depending on the water flow, various sizes of gravel particles. It is this sand and gravel that has traveled with the water flow from the Combe, that provides these vineyards that protrude past the limestone of the escarpment the drainage the vines require.  These are not, however, the soils that will produce the great premier cru, or grand cru, wines for which Burgundy is famed.

a graded sediment bedSoil suspension and graded bedding

Soil moves downslope by water erosion, the force of gravity, and even is transported by the force of significant wind. With movement, the particles within the topsoil are in a state of suspension. Geologists refer to this movement and suspension as turbidity. Because of their weight, gravel travels downward in the moving soil, creating a progressively sorted soil, with coarser pieces on the bottom, while the finer particles find their way to the top.  The result of this is called a graded sediment bed. (1)

While it is easier to see how a graded bed might be created in a stream bed below a ravine like the Combe de Lavaux, I was somewhat perplexed how this might occur in Alex Gamble’s Les Grands Champs vineyard in Puligny-Montrachet, see Clay part 2.1.  Here gravel bedding lay at 80cm, a little more than two and a half feet below the surface. Above the gravel, sat a foot and a half of heavy, yellow, clay-dominated soil. This was, in turn, topped by nearly a foot of loamy-clay soils. Vannier-Petit estimated these soil horizons, as geologists refer to them, were created between two and five million years ago by water runoff. What kind of run off?  I realized that the kind of runoff that creates graded bedding happens often, like in this photo (below), taken in Pommard during the winter/spring of 2014, by winemaker Caroline Gros Parent.

This is how graded bedding develops.
This is how graded bedding develops. Here the road to Pommard has flooded in the winter storms of 2014. Photo: Caroline Parent via twitter

Parent material

Geologists talk about a soil’s parent material because every element of soil came from a different material, which was then weathered, both mechanically and chemically, into various sizes. These minerals will then accumulate, either poorly sorted into an aggregate material, or they can be well sorted by the wind, water, or gravity into size categories. Sand and silt are generally said to have been created by mechanical weathering, although chemical weathering is always a present force, as long as there will be rain. Sand can be made of any parent rock material, but in Burgundy, there are sands made of granite, in addition to plentiful limestone sand. (2) We know this because there is loam present (as well as graded bedding), in the Grands Champs vineyard from the Saône valley fill below. The water that carried this non-limestone, Côte-foreign material, would have carried quartz sand with it as well when it created the graded bedding there. This gives us a very important insight into the construction of the soils of Burgundy.

Fine earth fractions

Fine Earth Fractions are the trinity of sand, silt, and clay. Gravel and sand can be made of limestone or other rock that has been weathered into smaller and smaller pieces, but silt is typically feldspar or quartz. Clay is much, much smaller in size, and is created by chemical weathering of rock. Its parental material can be limestone, granite or other stone.

Geologists grade soil minerals by size; the basis of which are particles that are 2 mm and smaller. These are called fine earth fractions and consist of sand, silt, and clay. In equal thirds of each of the three soil fractions is considered perfect for farming crops, and is termed loam. The various sizes of minerals in the soil makeup gives the soil its texture.

Clay, we have talked about in length in part 2.1, and differs from silt and sand because it is a construction from stone that has been chemically weathered, whereas silt and sand are derived from mechanically weathered rock. Additionally, clay is a construction of clay minerals that are bound with aluminum and oxygen by water and carries minerals within its phyllosilicate sheets. It is also important to mention that clay’s particles are considerably smaller in diameter, being less than 2 microns in size.  Soils with more clay hold more water,  so they require less frequent application. An overabundance of water in clay soils causes oxygen depletion in the root zone.  This can limit root development.  The abundant solvent calcium in the limestone soils Burgundy misaligned the clay platelets, loosening the soil, and allowing better drainage.

Diatoms (top) and Radiolarians bottom, fill the ocean floors with sediment.
Diatoms (top) and bottom, fill the ocean floors with sediment.

Silt is specifically formed from quartz and feldspar, and is larger than clay, being 0.05 mm-0.002 mm. We know that any feldspar in the soil, could not have come from weathered stone; neither limestone or granite, which was the dominant stone in the area when the limestone beds were forming, because it would have metamorphosed into a phyllosilicate clay mineral if it had. This means the feldspar has traveled onto the Côte, either from above or below the limestone strata.

While it might seem logical to assume the quartz in silt originated in the earth’s crust, and perhaps degraded from granite that was prevalent in the area, this may not be the case. The first problem is quartz is resistant to chemical weathering. And physical weathering like frost wedging of sand particles may continue to yield results beyond a certain size.

Researchers from the University of Texas at Arlington used (and I cut and pasted this) a “backscattered electron and cathodoluminescence imaging and measure oxygen isotopes with an ion probe.” They found that the 100% of silt quartz found in 370 million-year-old shales of Kentucky were made from the “opaline skeletons” of plankton, radiolarians,  and diatoms. This, they reasoned, might explain the lack of these kinds of fossils during the same period. These tiny animals had all been incorporated into the then forming shale. This may also be the case for the silt quartz of Burgundy, itself too having once been a Jurassic, seaside resort. This, in fact, this information also suggests this quartz silt may come from weathered shale that is much older than the limestone of the Côte.

A sandy soil horizon
A sandy soil horizon

Sand is larger than silt. being less than 2 mm, and typically is constructed of quartz or limestone particles. The limestone sand will weather to solvent calcium carbonate, but the quartz will not weather and will remain as sand. It is likely that significant quartz sand has been washed down from the hillsides, and certainly is a major contributor to alluvial soils below the combes. Sand drains so quickly that vines grown in sandy soil have more frequent water requirements, but require a lesser amount of water.  Adequate water maintains plant growth while minimizing the loss in the root zone.

 Plant and animal soil contributors

Grasses, with their dense root systems, are positively impactful to the topsoil. In their decomposition, darker soils are created to deeper depths, and the resulting soils also tend to be more stable.  In a monoculture of grapevines, many growers are finding this to be a significant advantage. In Australia, some grape growers are using grasses to help lower soil temperature in efforts to slow down ripening in an ever-warming climate.

Much is made by those practicing sustainable and organic cover crop encourage populations beneficial predator insects and birds, but grasses and cover crops also encourage subsoil organisms and microorganisms growth as well. Most common are bacteria and actinomycetes (rod-shaped microorganisms), which by weight have been found to be four times more present by weight than earthworms in healthy soils. While these are important to the quality of the wine, they are only an intricate part of terroir if it is practiced by the farmer.

The 25%: Air (and soil compaction)

Soil compaction relates to poor water infiltration and low oxygen levels. drawing: landscaperesource.com
Soil compaction relates to poor water infiltration and low oxygen levels. drawing: landscaperesource.com

The proper amount of airspace between mineral fragments is very important for vine growth and allow for water to penetrate and be retained by the soil. Soils with diminished airspace are said to have soil compaction, and compaction is difficult to correct once it has occurred. The Overly tight spacing between the mineral component of a soil restricts oxygen levels and contributes to a poor water holding capability.  Rainfall itself can cause some soil compaction, but most commonly walking or operating farming equipment on moist soils does the most damage. In drought years, soil compaction can lead to stunted vine growth and decreased root development. In wet years, soil compaction decreases aeration of the soil and can cause both a nitrogen and potassium deficiency. Additionally, without adequate porosity to the soil, water cannot easily penetrate the soil during a rainstorm. Water that cannot infiltrate soils of flat terrain can stagnate, which further compacts the soil,  or on sloped terrain will runoff, which can create erosion problems.

Positive effects of moderate compaction

As moisture of the soil increases, so does the depth of compaction.
As moisture of the soil increases, so does the depth of compaction.

Moderate compaction can have some desirable effects. Moderate compaction forces the plant to increase root branching and encourages secondary root formation. This additional root growth is the plant’s response to not finding enough nutrients with its existing root system. Plants with more extensive root systems are more likely to find nutrients that are not carried by water, like phosphorus.  Obviously, more compaction is not better, because it impedes root growth, lessens the oxygen in the soil, and repels water from penetrating the soil.

While deep tillage 10-16 inches can shatter the hard packed soil, studies have shown that crop yields will not return to normal following the effort. While there are factors that might cause the soil to return to compaction, like a farmer, unintentionally re-compacting their soils, more than likely tilling does not return the airspace that was lost in the soil itself. Further continuous plowing and tilling at the same depth can cause serious compaction problems on the soil below the tilling depth.

The 25%: Water (the key to everything that Burgundy is)

It should be impossible to talk about soil without talking about water, given it is optimally 25% of soil’s makeup. It is certainly tempting to pass over the subject of groundwater and lump it into erosion, but that would really shortchange our understanding of the Cote. Part of Burgundy’s success can surely be attributed to relatively steady rainfall year round, coupled with the fractured limestone’s ability to hold water until its reserves of water which is held within the stone can be recharged by future storms.

Good drainage, well-drained? Let’s reset the dialogue.

The infiltration of rainfall by the soil is the first and perhaps most important factor in recharging groundwater levels. Like I wrote of compaction, the soil has to be porous enough to penetrate the topsoil and subsoils successfully. The buzz word in the wine world is drainage, with terms like well-drained, and good drainage appearing often. I suppose we picture the roots drowning in mud if there isn’t good drainage. But the idea of good drainage really simplifies the issue. Drainage can have to do as much to do with compaction as soil materials or slope. Soil drainage is important in fighting erosion as well not causing additional soil compaction. Good drainage, which is what happens with a well-aerated soil, allows the vines roots sufficient oxygen and nitrogen and allows the roots to take in nutrients like phosphorous and potassium. But none of this can happen if the soil releases rainwater too quickly, and the vine can perform none of these vital tasks. The reality is, it is not the fact that a soil well-drained, but rather it drains at the adequate rate for a given rainfall. Obviously, this will not always be a perfect equation since rainfall varies greatly depending on the year and the time of year.

The speed of drainage

water movement through various soil types. source: usda-nrcs
Water movement through various soil types. source: USDA-nrcs

The kinds of materials that make up the soils contribute greatly to the rate of water ability percolate through the material. The speed of the mater’s movement depends on the path the water is channeled in. The most direct path that is in line with gravitational pull will give the fastest drainage.

Water movement comparison through sand and clay. Soure Coloradostate-edu.
Water movement comparison through sand and clay. Source Coloradostate-edu.

Sandy soils, as one might expect, drains quickly because it consists of only slightly absorptive, small pieces of stone, that allow the water to essentially slide right past.

Clay, on the other hand, is very dense and plasticity. These characteristics, as you might expect, would be resistant to allowing water to pass through, and large bodies of transported clay can redirect horizontally, the flow of water percolating through from above due to it’s slower absorption rate. But what isn’t obvious is that clay’s construction encourages capillary action. The clay body will distribute water throughout its mass, counter to gravitational pull, becoming completely saturated, before releasing excess water through to the material below.

Argillaceous Limestone
Argillaceous Limestone with its horizontal fracturing slows water percolation. click to enlarge

Highly fractured limestone that is still in place, is often is fragmented in a prismatic pattern. However some limestones, like this soft argillaceous limestone to the right, with its high clay content, may fracture horizontally. The type of fragmentation would depend on the stresses upon the stone, the freeze-thaw effects of water and temperature, as well as the material of the stone’s construction. Clay based stones will tend to fragment horizontally and when they do, they are considered platy, and water will percolate more slowly than stones that fracture in a prismatic fashion.

Water movement through soil
The hillside of the Côte is a recharge area for water collection, while the valley below is a discharge area, where excess water is expelled. The water table is at the capillary fringe. Water uses faults and fissures to move quickly into and out of the saturated zone. It is likely there are aquifers, meaning caves which have been cut out of the limestone by carbonization below the Côte, where the water is stored.

 

a small karst aquifer Photo:planhillsborough.org/
A small karst aquifer in Florida. Photo:planhillsborough.org/

Groundwater, the water table, and karst aquifers

In writings regarding Burgundy, very little is said about ground water, other than there are no cellars built underground in Puligny because the water table is too high there. A plentiful water supply may be one of the features that propel the vineyards of Puligny into the ranks of the worlds best. As my diagram above shows, water percolates through the soil and stone. This upper section is called the vadose zone, or unsaturated zone. Slabs of limestone, fissures, faults, and clay bodies all can change the course of the water flow. Each horizon of soil and each layer of stone have their own rate of percolation. With this much limestone, it is very likely there are karst aquifers or large caves caused by the carbonization of calcium carbonate beneath the Côte, but I could find no specific mention of aquifers in close proximity to the Côte. There is a mention in a European Academies Science Advisory Council‘s country report for France, that in Burgundy there are “karsified Jurassic limestone layers” somewhere in the region, but nothing more is elaborated upon.

There is a very famous and massive karst aquifer with seven very deep layers that spans from north of Burgundy across the Paris basin to the English channel. The deepest level of water is brackish. The uppermost section is called the Albian sands sits at than 600 meters, and was first was drilled into in 1840 taking well more than 3 years to achieve. The water there is 20,000 years old, and there has been discussion whether the water should be considered fossil, meaning there is a question whether there recharge from the water above, or not.

 

Next up: Understanding the Terroir of Burgundy, Part 3: Confluence of stone, soil, and slope

 


 

(1) Interestingly, larger stones, especially the flatter, rounded shaped stones that the French refer to as galets, tend move to the surface, probably because of their larger displacement values.

(2) Sand from other parent rock material is likely to be available as well.

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 1.1 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.

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.