Geology in a Vineyard in France

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Demystifying Sonoma's AVAs

Join us on this exciting visit to Sonoma Valley!


In our quest to demystify the complex and overlapping array of the Sonoma AVAs, we will visit select wineries that are true to their respective terroir. The French would say they are “correct”. We will discuss how the topography of the region reflects effects of tectonic forces — the San Andreas, Rodgers Creek and related faults, and the east-west compressional forces that have folded the terrain into discrete valleys, ridges, alluvial fans and river corridors.


We will spend the weekend visiting vintners at their wineries, to learn about their soils and wine-growing practices, and how these affect their wines. We will learn about their vinification processes and of course, taste their wines.


A professional driver and comfortable bus will transport us from start to finish so there is no need to worry about driving once you get there.


A well-regarded local chef and her team will prepare dinner on Saturday night using carefully selected seasonal and local ingredients. Paired with elegant wines selected to represent the Sonoma AVA’s, the meal will be a culinary and wine treat for you.


We pair our picnic lunches of hand-selected charcuterie and cheeses from a local provider with choice Sonoma wines.

"What is wine without the soil, the climate and the people?”




Former Research Geologist with the US Geological Survey

David G. Howell is a Fellow of the American Association for the Advancement of Science and the Geological Society of America. He has been working with Napa Valley vintners for more than twenty-five years and is the co-author of The Winemaker’s Dance: Exploring Terroir in the Napa Valley. After retiring from the US Geological Survey, Howell was an adjunct professor in Stanford’s School of Earth, Energy & Environmental Sciences from 2005 to 2009. He received a PhD from UC Santa Barbara and has authored more than 150 scientific articles.


Former science center Director with the US Geological Survey.

Owner, Hexagonvins and wine enthusiast. He has explored France, l’Hexagone,  and its wine regions annually for more than thirty years. He and his wife led hiking tours in the mountains of Provence for many years. He is retired from the US Geological Survey where he helped to establish the US Global Change Research Program, and led the USGCRP’s Arctic data team that received the Presidential Design Achievement Award from the National Endowment for the Arts. He has explored the geography, food, and wines of Alsace, Burgundy, Beaujolais, Champagne, the Rhône, Provence, Languedoc, the Roussillon, the Loire, the Southwest, and Bordeaux.


Chief Operations Officer (and Ambassador of Fun)

 Koffi is a wine enthusiast and former sommelier candidate. Student of all things wine and geology, Koffi has organized and led wine excursions to several California wine regions. He has produced wine as a “Garagist”, has done internships at several California wineries, and has worked as tasting room manager. Over the years, he has assisted David Howell with the Stanford University’s on-campus Geology of Wine classes as well as Napa field trips offered through the Continuing Studies program. Koffi is fluent in French.

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