Sunday, February 7, 2016

Soil and Wine - Part 1: Starstuff and Seashells

Earth was born with our Solar System 4.5 billion years ago by the gravitational collapse of a molecular cloud, which was created by the death of a star, on the outskirts of the 13.2 billion year old Milky Way Galaxy. So our star, the Sun, is actually a second or third generation star.

For its first billion years our planet was a fiery and violent hell as its gravity pulled in debris from the Solar System's creation, increasing its mass and forming the Moon. The meteors and debris that it collided with and collected were made of various elements, minerals and gases. Earth is mostly iron, especially in its center, and its other major ingredients are silicon, oxygen, aluminum, and magnesium. As the planet congealed it created an atmosphere with the release of methane, ammonia and hydrogen.

Once the planet had an atmosphere it could actually hold on to the ice that was delivered by meteors and comets. Instead of evaporating back into space it became Earth's water, trapped in an endless cycle of evaporation and condensation. Used and cleansed over and over again. Through billions of years the land and oceans shifted. Early life forms in the oceans gave the atmosphere enough oxygen through photosynthesis for itself and other life to evolve and breath it in. The presence of plants and creatures that lived and died, then decomposed or were fossilized, created new forms of soil and liquids with organic matter. Ice ages and glaciers were incredibly impactful to both life and the Earth's surface.

Now think about your favorite Chablis. Crisp, clean, zingy Chardonnay bliss. The limestone in the Kimmeridge Clay soil of Chablis is one of the factors in why it's so outstanding. Limestone is the skeletal remains of early life forms and other prehistoric shelled creatures, layered in land once covered in water or where moving glaciers deposited them. It's a gift from the ghost of CreepyCrawlymas past.

Let us recap. The death of a star lead to the creation of our own star (the Sun) and our Solar System. The Earth and its water were created from starstuff. For most of human history we've cultivated grapevines out of Earth to make wine... a beverage that Galileo called "sunlight held together by water". It's the circle of the cosmos and it rules us all. And it's so goddamn beautiful.

How about we go back to the glaciers for a paragraph to talk about grapes, this being a wine blog. Why is there only one species of grapevine native to Europe, vitis vinifera, and hundreds to the Americas? Here's one theory from Proof: The Science of Booze. Take a look at the mountain ranges on a map. Europe's mountains go horizontally, or west to east, and America's goes vertically, or north to south. So the grapevines of the Americas got a lift from glaciers and were transplanted. The grapevines of Europe got trapped and destroyed by them instead, the only survivor being vitis vinifera. And it was probably the Moscato family that was the victor, spawning off all the other families and varieties we know today. If you don't think that's tight then get out of my face.

As you can tell I'm a big admirer of Stephen Hawking, Carl Sagan, Richard Dawkins, and Neil deGrasse Tyson. It's not because I think I'm smart. I'm some dude that knows about wine, enjoys selling it to people, sucks at math and can't lipread to save my own life. I have no illusions of my intelligence. Maybe of my abilities, but not my intelligence. But I'm just not the kind of guy you can just say "this does this" and expect me to accept it and move on. I need to know why it does that, and if you can't explain that to me then it's either useless information or not good enough, so I'll either forget it or find out my own damn self. Thus, a big chunk of my entertainment time is spent doing the latter.

While reading yet another book on wine it occurred to me that, although I know the effects of different soils on wine, I really don't know enough about the soils itself... and FLICK! There's the light switch in the brain. Gathering information on a large topic while writing about it is a great way to learn and retain. So here I go again, using this blog as a platform to further my education. I'm not a geologist (a scientist of Earth's solids and liquids) or pedologist (a scientist of soil), and I do realize I risk making a complete fool of myself, but I do love researching and writing about really geeky things here. So let's get nerdy with a three-part series!
soil /soil/ : the upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles. 
Layers of soil
Soil is a showcase of minerals, gas, liquid and organic matter, combining Earth itself with the history of life that roams it. Minerals are inorganic compounds (the hard stuff from starstuff) and they can come in small grains or compressed together as rock. Organic matter is compounds that come from plants, animals and the waste they produce. Soil also loves to collect and release Earth's most important gas: carbon dioxide. The plants that grow in the soil use that carbon dioxide, as well as the supply in the air, and output oxygen, which we breathe... and in return exhale carbon dioxide. This is no coincidence.

There are numerous systems for soil classification and they're pretty confusing, so I'm going to go by what makes the most sense when you're talking about wine. By granulometry or physical texture (particle/grain size and distribution) there are four basic categories: CLAY, SILT, SAND and ROCK/STONE. Other than carbon dioxide, soil also provides other needed nutrients, minerals and water to its plants, so water retention is important for fertility.

And about that fertility thing... the best wine comes from grapevines planted on soil that's not so fertile. You want the water to drain away easily, and you want the roots to dig deep in order to get to its water. When that happens it forces the vines to grow less clusters and focus on providing for the few, thus making better quality grapes. Climate and weather is important too. If everything is perfect growing conditions then the vine wants to get itself a protective canvas and grow its wood in size. If it has to put up a fight in a marginal climate instead, then it sacrifices those goals to put more energy into its grapes for survival. A struggling and stressed grapevine makes beautiful wine when tended to properly. This is why the hotter and more fertile lands that grow grapes all across the world are typically used for jug wine.

Before I get into those four categories of physical texture, there's a few things that should be addressed first: volcanic soil and limestone. These are pretty important and just can't be categorized under just one of them.


An even broader stroke than "clay, silt, sand and rock/stone" is whether it's volcanic soil or not, because volcanic soil can be all of those things. The differences are that it came out of a freaking angry volcano or fissure and what it's made of. Vent-based soils are rocks or molten beads that were shot into the air and cooled off before it even hit the ground. PUMICE, a gray rock containing rough volcanic glass, is a product of this. Lava-based soils come from the lava flow, the reason that my daughter has to jump from couch to couch and not touch the floor. 90% of it is BASALT, a fine-grained, black rock made from solidified lava or magma (obviously) that's full of calcium and iron.

So what makes volcanic soil so great? Volcanoes are on planets and moons that have ruptures on the surface. Saturn's moon Enceladus erupts ice out of its volcanoes just because it's a cold-hearted badass. Remember when I said that Earth was originally a fiery and violent hell? It's still like that, even if the exterior image has improved. Incredibly hot magma is about 20 miles under you and it likes to collect into magma chambers. If it's near the end of one of Earth's seventeen tectonic plates or where the surface gets thin, there can be a rupture. These ruptures let the tomato sauce pour out of the gravy boat... they're volcanoes. Magma can be anywhere from 1300 °F to 2400 °F and it's super rich with minerals and nutrients. It's the bringer of death in eruption and the bringer of life in dormancy.

Many vineyards and wine regions on volcanic soil are celebrities. There's the Finger Lakes (New York), Napa Valley (California), Pfalz (Germany), Taurasi (Italy), and Tokaji (Hungary) just to name a handful. Then there are certain diva varieties of grapes that demand volcanic soil. For example, if Aglianico isn't on volcanic soil then you may as well not grow it at all. It just belongs there.

The unique volcanic soil JORY covers 300,000 acres in western Oregon. Once upon a time, millions of years before us humans came around, fissures by the Washington-Idaho border spewed out lava that traveled all the way to Willamette Valley. Now it's Willamette's secret weapon. Technically a clay, it's basalt-based, very deep, fine-grained, well-drained and reddish in color. Great for growing anything from Christmas trees to grapevines. Their Pinot Noir revels in it.

GRANITE is a feldspar/quartz-based rock made from crystalized magma under the Earth's surface, but I'll save that for Part Three, which will be on rocks and stones.

The one thing to not overlook about volcanic soil is that the magma chamber under the volcano involved may have died out long ago or it could still be active. There are people that risk their lives to be right next to an active volcano so they can grow their crops, including grapevines, because of the superior benefits in the soil. But more often than not that volcano is a dead parrot.


Limestone is a theme that runs across the soil types. It's all over the place. Chalk is fine limestone. Tuffeau can be both a chalk or stone limestone. Kimmeridge Clay is clay limestone. So I think I should touch on it before we head into Part Two where we get into the whole clay, silt, sand and rock/stone thing.

Shell imprint in limestone
Without prehistoric life there would be no limestone and there would be no chalk for drawing hopscotch courts on the sidewalk. Limestone is rock made of stone and fossils from all sorts of prehistoric shelled marine life. It was the Romans that figured out how to use limestone and crushed rocks to invent cement... probably so they would have a surface to play hopscotch on.

Limestone is calcareous (its main component is calcium carbonate), so of course its most important nutrient is calcium. For the past few years I was having issues with bottom rot in my tomatoes, a sign of calcium deficiency, so this past year I threw some lime in the soil and it wasn't an issue at all. Another important chore of limestone in crop soil is to neutralize soil acidity, because calcium-rich soil is low in it. Limestone is alkaline, meaning it has a pH of 7 or greater. The numbers for pH is backwards than what we're used to. The higher the pH number the lower the acidity rather than higher. Your average vineyard soil has about a 5.5 pH, so if a limestone soil has a pH of 8 then it's less acidic than your average soil. When it comes to viticulture, calcium helps the grapes maintain acids late into the growing season, ending with an acidic wine. Thus, the lower the acidity of the soil the higher the acidity of the wine.

At its finest physical property, limestone is CHALK. As a top soil it has great water drainage but has a nice moisture retention, and as a subsoil it compacts to absorb said water incredibly well. But it's very soft and porous, allowing roots to effortlessly grow down to that subsoil. So why would you put vines on chalk? Take a look at these regions: Champagne and Cognac have a lot of chalk in their soil, and at a lesser extent Sancerre and Chablis (both mostly limestone clay). Champagne especially, being so far north and its continental climate so unforgiving to grapevines, wouldn't be able to grow those vineyards if its chalk didn't also absorb solar heat and release it back onto the vines. There's no way. Also, as I explained in the previous paragraph, chalk is alkaline, resulting in more acidity in the grapes. Champagne and Cognac both absolutely need high acidity for their base wines before they're transformed into their respectful final products. And acidity is part of the allure of both Sancerre and Chablis. So I would say it works out. Another variety that loves chalk soil, outside of Chardonnay and Sauvignon Blanc, is Pinot Blanc.

MARL is a combination of limestone and clay. There'll be more on that later when I go over clay, but there's one that should be talked about now. It's an illuminating white, chalky marl soil unique to Spain called ALBARIZA and it covers the southern region of Jerez (where they make Sherry) but also a bit in the northeastern region of Penedés (where they make Cava). It's anywhere from 30% to 80% chalk, then limestone, clay and sand. It's what's known as diatomaceous earth, meaning the chalk and limestone is from fossilized hard-shelled algae called diatoms. Things get hot in Spain and albariza naturally creates a crust on its surface from the heat. Taking advantage of this, vineyard workers will till the soil before that happens to purposely compact it and increase its water retention, so when the crust forms it'll act as a cap and keep enough water underneath for the vines to survive the hot months instead of draining away or evaporating. The Palomino variety takes a special liking to albariza so it's credited with being an important part of Fino Sherry, along with flor yeast, and Manzanilla Sherry, along with the effects of the ocean.

Back in the Cretaceous Period, ninety million years ago, France's Loire Valley was underwater and bustling with the tiny aquatic invertebrates called Bryozoa. They had tentacles to capture particles of food and hung out together in enormous colonies. These creatures died and fossilized with sand to become TUFFEAU or TUFA, which comes in stone and a chalk-like soil that's rich in iron and magnesium. There's a volcanic soil called tuff that's also known as tufa but it's unrelated to this one. This tufa makes beautiful white buildings and art as stone. As a soil it's found in vineyards all over Loire Valley, but most adored by the Cabernet Franc in its Chinon and Saumur-Champagny regions. This is because grapes from iron-rich soils will make wine with more tannin and structure, so it's more suited for reds than whites.

To the east of Chinon and Saumur-Champagny, in Sancerre and Pouilly-Fumé, the soil turns from Tuffeau to another form of limestone: KIMMERIDGE CLAY. But that will have to wait for Part Two, along with ex-limestone TERRA ROSSA. Cliffhanger!

Part Two: Terroir and Texture is about clay, silt and sand. Part Three: Roots Among Rubble is about rock/stone.

- Joey Casco CSW/CSS

Thank you to my proof readers and contributors: Christopher Bohm, Lori Budd (Dracaena Wines), Graham Richardson, Daniele Rosti (Campochiarenti), and Franck Boulbès (Cellier Domesticus). You guys are so awesome.


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