Terrane Terroir and What’s Up with this Purple Dirt Anyway?

22 Dec

As far as we can tell dinosaurs did not drink wine. Yet while the dinosaurs were leaving their bones in the mud farther east in Utah, the dirt that would become Hidden Ridge was being washed into the sea on to a narrow continental shelf and cascading in underwater landslides into the trench where the ocean floor was sliding under an island arc something like the island arcs in Southeast Asia today.
These offshore sediments gradually accumulated over a period of about a hundred million years into a linear terrane that underlies most of the coast ranges of California. This terrane is suitably called the Franciscan after the good Fathers on donkeys that first brought vineyards and winemaking to the state.
Terrane, terroir, but not terra firma. Certain chemical processes when sediments are compressed and melted into rock form magnetic crystals that align with the North Pole when they form. From these we can tell that Hidden Ridge was once in an entirely different appellation, probably Central Coast near the current position of Paso Robles.
Slippage like that along the San Andreas Fault today has been going on for a long, long time and the combination of ocean floor sliding under and northward slippage caused some unusual intrusions into the Franciscan. These intrusions were much more like the ocean floor, rich in Iron, Manganese, and Magnesium. Hydrothermal activity, pretty much like the Geysers today, leached Iron from the intrusions and injected it into the soil above leaving us the dark red to purple Iron rich soils of Hidden Ridge.
Iron makes blood red and it is part of the coloration of grape skins. Wine color comes from the skins. The unfailing color and phenolics of Hidden Ridge wine derive from this soil.
Valley soils have been washed down from many different rocks in the surrounding mountains. From the Santa Rosa side the Mayacamas Mountains begin with a wide band of relatively recent (we’re still talking millions of years) volcanic rocks called the Sonoma Volcanics. As one climbs out of Rincon Valley on the Calistoga road the Sonoma Volcanics are expressed as light colored tephra or tuffs that can easily be mistaken for limestone. This is volcanic ash, like Mt Saint Helens on steroids. Above these after the first bridge on the St Helena Road one finds buff colored ten million year old sandstones laid down when San Francisco Bay extended way up here. Only near the top of the Mayacamas Mountains where all the younger stuff has washed off does one find the Franciscan and Hidden Ridge.
In the valley bottom soils the red Iron has been diluted to brown and lighter buff colors from less Iron rich rock washed down after the dinosaurs left town.
Does purple dirt make an exceptional mountain cabernet? You bet it does. Here’s to the red blooded dinosaurs!

Wine, Volcanoes, and the Dioxides

6 Oct

Making wine teaches important lessons about the wee beastie soup we live in, call it the dim sum. It also holds lessons about Carbon and Sulfur. Carbon and Sulfur were instrumental in the evolution of life on this planet, and likely by no coincidence oxides of Carbon and Sulfur are the second and third most prolific exhalations of volcanoes, after water.


Most folks understand the fundamental role of Carbon in the chemistry of life, and many that one of the more plausible scenarios for the terrestrial evolution of life involves reducing Sulfur in the anaerobic environment of oceanic hydrothermal vents . Those so inclined may draw a volcanic metaphor for life.

NOAA hydrothermal vent

For billions of years life existed only in the oceans as a microbial soup I like to call the dim sum. One can also think of it as wine. Lest we underestimate the industry of our wee predecessors, they are currently found in our deepest holes drilled into the crust and in the highest reaches of the atmosphere. Our human ancestors discovered that the fungi we now call yeasts quickly turned mashed grains into beer and bread, and collections of fruit into wine.

The dioxide of Carbon became the basis of a balanced economy of photosynthesis and respiration we consider ourselves the culmination of. The dioxide of Sulfur, however, is the evil twin, the anti-life.

While many beasties, including yeasts retain the anaerobic Sulfur reducing metabolic pathway for tough times, the usual resultant, Hydrogen sulfide is extremely toxic to aerobic creatures and is an unpleasant component in wine. Research on selecting yeast strains to eliminate Hydrogen sulfide has demonstrated a previously unknown reducing pathway that produces free Sulfur.

The antimicrobial use of Sulfur in winemaking is at least as old as the Romans and Sulfur was our primary antibiotic as recently as World War I.

When I hear the Carbon wags expostulating about  volcanic Carbon dioxide causing mass extinctions, I yearn to bring them down to earth with a whiff of my stock sulfite solution.

Skull Crossbones

Why Miocene?

27 May

The Miocene is the name of a geological epoch derived from Greek words that generally mean “less recent”. Most geology is “less recent” than our human time frames but “less recent” is a good thing when it comes to big wines. Around Calistoga and the Napa Valley there was a lot of volcanism in the late Miocene and much of the volcanic rock visible in the hills above our tasting room is of Miocene age.

Epoch, if you go by spelling, is one of those words coined by someone with no sense for the mouth feel of words. Fortunately better palettes have prevailed and it is commonly pronounced “epic”. Epic pretty much summarizes the wines we will be making, so when you say “Miocene Wine” consider the mouth feel. Think “less recent”, and call it the Miocene Epic.