New geologic mapping of the northwestern Willamette Valley, Oregon, and its American Viticultural Areas (AVAs)—A foundation for understanding their terroir

Open-File Report 2018-1044
By: , and 

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Abstract

A geologic map of the greater Portland, Oregon, metropolitan area is planned that will document the region’s complex geology (currently in review: “Geologic map of the greater Portland metropolitan area and surrounding region, Oregon and Washington,” by Wells, R.E., Haugerud, R.A., Niem, A., Niem, W., Ma, L., Evarts, R., Madin, I., and others). The map, which is planned to be published as a U.S. Geological Survey Scientific Investigations Map, will consist of 51 7.5′ quadrangles covering more than 2,500 square miles, and it will represent more than 100 person-years of geologic mapping and studies. The region was mapped at the relatively detailed scale of 1:24,000 to improve understanding of its geology and its earthquake hazards. More than 100 geologic map units will record the 50-million-year history of volcanism, sedimentation, folding, and faulting above the Cascadia Subduction Zone. The geology contributes to the varied terroir of four American Viticultural Areas (AVAs) in the northwestern Willamette Valley: the Yamhill-Carlton, Dundee Hills, Chehalem Mountains, and Ribbon Ridge AVAs. Terroir is defined as the environmental conditions, especially climate and soils, that influence the quality and character of a region’s crops—in this case, grapes for wine.

On this new poster (“New geologic mapping of the northwestern Willamette Valley, Oregon, and its American Viticultural Areas (AVAs)—A foundation for understanding their terroir”), we present the geologic map at a reduced scale (about 1:175,000) to show the general distribution of geologic map units, and we highlight, discuss, and illustrate six major geologic events that helped shape the region and form its terrior. We also discuss the geologic elements that contribute to the character of each of the four AVAs in the northwestern Willamette Valley.

Suggested Citation

Wells, R.E., Haugerud, R., Niem, A., Niem, W., Ma, L., Madin, I., and Evarts, R., 2018, New geologic mapping of the northwestern Willamette Valley, Oregon, and its American Viticultural Areas (AVAs)—A foundation for understanding their terroir: U.S. Geological Survey Open-File Report 2018–1044, https://doi.org/10.3133/ofr20181044.

ISSN: 2331-1258 (online)

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Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title New geologic mapping of the northwestern Willamette Valley, Oregon, and its American Viticultural Areas (AVAs)—A foundation for understanding their terroir
Series title Open-File Report
Series number 2018-1044
DOI 10.3133/ofr20181044
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 74.00 x 36.03 inches
Country United States
State Oregon
Other Geospatial Northwestern Willamette Valley