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What does "terroir" mean?

Quality winemaking starts in the vineyard. Starting in the 1500s, the French experimented with different plantings in different areas, and through trial and error found the perfect match between grape variety and

environment. In the new world winegrowers are just beginning to realize the importance of terroir and it has improved wine quality to world class in a few decades.

The concept of terroir incorporates the notion of site and location which includes all factors that work together to create a region with particular wine characteristics. The factors start with the rock and resulting soil, through the climate and vineyard practice, ending with the winemaker’s art and the consuming public. Now we are becoming aware of the scientific basis for our experience with terrior. Here we consider the major geologic factors of terroir: the parent material and the soil mineralogy and texture.

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Terroir Expertise

I am a geologist and researcher applying my background to the holy grail of all winegrowers: What is the effect of geology and soil on wine quality?. My approach is to meet winegrowers in the vineyard, discuss the various factors that might affect wine quality there, and study the geology and soils hot spots where the best quality grapes come from. My conclusions are that balanced chemistry, low CEC clay in and a open texture are essential ingredients for great wine. This is elaborated in my papers and abstracts cited below.


I also am a educational consultant on all aspects of geology related to winegrowing, and have done projects for Jackson Family Farms, Benziger Family Winery, Vision Cellars, MacLoud Family Vineyards, Goldridge Pinot, Sonoma County Wine Library,Poplar Vineyards and Iron Horse Vineyards. I have presented my ideas at several local symposia on Wine Quality, sponsored by Russian River Winegrowers, Sonoma County vineyard technical group, Sonoma County Wine Library Associates and Green Valley Winegrowers in Sonoma County, California.

I also support the demand for geology and soils information for winery publicity, including information for point-of-sale materials, wine labels and websites. Check

out Eric Sussman’s web page for Radio-Coteau winery as an example: This site has engendered much interest driven by geologic information. A label without reference to soils types and roles is leaving one half of the story of the wine in the dust. I am available for vineyard meetings, writing and conferences on soils and wine quality.

For more information: Check out both my article and ad for Practical Windery & Vineyard.

See my Poster on geology soils and wine quality in Sonoma County from Terroirs 2006 meeting. (large file)

Download my Rate Sheet here.

Publications and Activities:


Field trip to southern Sonoma County-Geology and Wine: CSTA Field Trip, October 20, 2006.

New download:  Terroirs of Sonoma County-Simplified (with characteristics of AVAs), In Powerpoint. Caution: because this is a large file, it would be best to have a high speed connection to the WWW.

Also, Sonoma County Geology, Soils and Wine quality; Powerpoint presentation from Sonoma County Wine Library Associates annual meeting, 2/2/06   

Past Publications and Links

Guidebook to field trip, Geology soils and wine quality in the Santa Clara Valley. Geological Society of America Cordilleran Section Meeting, San Jose, 2005,

"Revised soils and wine quality paper 3/05". Please see accompanying tables and graphics.

"Diverse Geology/Soil Impact Impact Wine Quality", Practical Winery and Vineyard Magazine, Sept-Oct, 2001. and republished in Sonoma County Grape Growers Association website in 2001. This will introduce you to the subject.

"Soils and Wine Quality, the Terroir Connection" an abstract of paper presented at the National Geological Society of America Annual Meeting in Reno 11/15/00 is another introduction.

An abstract written in 2003, presented at National GSA meeting in Seattle: "Terroirs of Sonoma County, California: Geology, Soils and Wine Quality in the Vineyard."


Sonoma County has several wine AVAs (American Viticultural Areas) that are in part determined by climate and geological features.

Map of Appelations and Geology of Sonoma County and Cross section of Russian River AVA, both revised 2006.

Table showing geologic units, soil units and characteristics in Sonoma County.

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TW 3/9/06