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et al., 2013). Elsewhere in the red hills of Dundee Jory, Ultisols are
Figure 1. Simplified geological map of the Willamette Valley, Oregon, USA, METHODS
with distribution of vineyards (modified from Moore, 2002; with bauxite
occurrences from Libbey et al., 1945).
these Ultisols are developed on Oxisol paleosol remnants between
flows of the Columbia Basalt Group (Libbey et al., 1945; Liu et al.,
2013) dated at 15.7 Ma (Martin et al., 2013). Elsewhere the Oxisol
bauxites below the Jory clay loam are 18 m thick (Fig. 2). Such
Oxisol paleosols required mean annual temperatures of at least
17 °C and mean annual precipitation of at least 1100 mm during
the middle Miocene (Retallack, 2008, 2010). In contrast, from
1971–2000, Salem had a mean annual temperature of 11.4 °C and
a mean annual precipitation of 1016 mm (National Oceanographic
and Atmospheric Administration, 2015), so that Ultisols are the
most deeply weathered soils forming in Oregon today (Lindeburg
1 GSA Supplemental Data Item 2016052, compiled data on wines and soils with graphs of additional vintages, is online at www.geosociety.org/pubs/ft2016.htm.
You can also request a copy from GSA Today, P.O. Box 9140, Boulder, CO 80301-9140, USA; gsatoday@geosociety.org.
developed on middle Miocene Grande Ronde basalt without the
bauxitic paleosol (Otte et al., 1974).
Other wine-producing soils of middle Pleistocene terraces that
cut into marine sediments are Bellpine Ultisols and Willakenzie
Alfisols, developed on volcaniclastic siltstone and sandstone, such
as the Spencer Formation (Otte et al., 1974; Patching et al., 1987;
Fillmore et al., 2009). These Alfisols are more nutrient-rich and
less acidic than Ultisols, but both have the lowest pH near the base
of thick clayey (Bt) horizons. In contrast, soils formed from
Missoula Flood deposits and loess are less acidic and more fertile
Mollisols of the Woodburn, Hazelair, and Chehulpum Series
(Otte et al., 1974; Gerig et al., 1985). The 16 distinct soil series and
variants of this study are detailed in the GSA Supplemental Data
Repository1 and provide an array of substrates for wines.
The Willamette Valley is a cool and humid climate viticultural
district well suited for Pinot Noir grapes (Jones et al., 2012).
Irrigation is not necessary in such climates, and vine vigor is
limited by low soil nutrients (Burns, 2012).
GSA TODAY | www.geosociety.org/gsatoday
Our choice of Pinot Noir wines from the Willamette Valley for
this study was due to long experience with local vintners and soils,
and particularly, the “great debate” about differences in the taste
of wines from Jory versus Willakenzie soils (Burns, 2012). To
supplement such small-scale studies, we compiled all available
metadata from the Web pages of all 177 wineries of the Willamette
Valley Wineries Association, whose technical sheets give wine and
grape pH and total acidity, grape sugar content, wine alcohol
content, harvest dates, recommended price, and vineyard location.
Sugar content in weight percent is given by the wine industry term
“Brix,” and all these commercial data were obtained using twenty-
first-century equipment and industrial standards. By experi-
mental design, as many factors as possible were kept constant:
data were limited to a single grape variety (Pinot Noir), a single
vinicultural area (Willamette Valley), and grouped by vintage (to
equalize climate effects). Blended wines were excluded, and
single-vineyard single-clone wines were located using Google
Earth and then checked in county soil surveys (Williams et al.,
1972; Otte et al., 1974; Knezevich et al., 1975, 1982; Green et al.,
1982; Gerig et al., 1985; Patching et al., 1987; Fillmore et al., 2009).
These same soil surveys were the source of soil data, which
included both maximum and minimum soil pH (determined by
pH meter on 1:1 soil:water), cation exchange capacity (by ammo-
nium acetate displacement of Ca2+, Mg2+, K+, Na+), depth to base
of clay-enriched (Bt) horizon, and clay and organic matter content
(both weight percent) in representative profiles for each county
survey. Geological data are from Walker and McLeod (1991).
Some wines were excluded because there were multiple soil series
in a single vineyard area when checked with county soil surveys.
Vintners vary in the extent of data recorded, and few vintners
posted archival data back to 1999. In the final database of 267 wines,
only the 2008, 2009, 2010, and 2011 vintages had 20 or more
wines (see the GSA Data Repository Supplemental [footnote 1]).
Uncontrolled in these data were details of viticulture other
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