Geology of the Walla Walla Area

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Geology of the Walla Walla Area
The French use the term Terroir to describe the
complex interplay of temperature, sunshine,
rainfall, soil, bedrock, viticultural practice,
and other physical factors that influence the
character and quality of wine
Dr. John D Winter Department of Geology
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Defined by elevation contour on S and E, and by
lines approximating drainage divide on the N
Revised effective April 27, 2001 VAs defined
by US Bureau of Alcohol, Tobacco, and Firearms-
define by geography Appelations of France
defined in terms of wine characteristics
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The Modern Plates
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Three types of plate boundaries
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Three types of plate boundaries
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Age of the ocean crust
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Hot Spots
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Hot Spots
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Convergent boundary

• Three sub-types
• Ocean-Continent
• Ocean-Ocean
• Continent-Continent
• Can you name an example of each?

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Plate Tectonics in the Pacific Northwest
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Igneous Processes
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The Edge of the North American Craton
Mantle has low Rb which ? 87Sr over time, so low
87/86 Old continental crust has high Rb so high
87/86
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Terranes of NE Oregon
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Terranes of NE Oregon
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Terranes of NE Oregon
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Terranes of NE Oregon
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Filling of the Columbia Embayment
Westward roll-back of subduction Fills Columbia
Embayment Stabilized near present location for
40 Ma Cascade range Uplift affects climate on
east side Volcanoes supply ash to winds and area
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The Columbia River Basalts
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The Columbia River Basalts
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The Columbia River Basalts
Aerial extent of the N2 Grande Ronde flow unit
(approximately 21 flows).
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The Columbia River Basalts
Location of the exposed feeder dikes red) and
vents (blue V's) of the southeastern portion of
the Columbia River Basalts.
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CRBs probably result from SRP-Yellowstone
hot-spot- difficult to explain northward
deflection
WW
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The Columbia River Basalts
Basalts yield excellent soils in Hawaii and other
tropical areas where rainfall is high and the
climate is warm Our soils in WW are not derived
from the underlying basalts-an unusual feature
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Continental Glaciation 125,000 until 13,000
years ago
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Continental GlaciationWind-blown Loess deposits
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Continental GlaciationWind-blown Loess deposits
Palouse Hills to north of WW gt 10,000 km2 and up
to 75m thick (depends on sub-loess topography)
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The Great Floods 12,000 years ago
Ice dam founders and releases up to 2500 km3 of
water out across the plateau
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The Great Floods 12,000 years ago
J Harlan Bretz in 1930s- a controversial proposal
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The Great Floods 12,000 years ago
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The Great Floods 12,000 years ago
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The Great Floods 12,000 years ago- Burlingame
Canyon
Suggests up to 90 individual floods WW received
silts as slackwater deposits Sediments range
from gravels near Wallula to massive silts and
sands toward Blue Mts Winds continue to
redistribute loess, silts, ash, etc.
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Uplift of Blue Mts.Erosion by river system
Mill Creek, Cottonwood, Birch Creek...Walla Walla
River Valley erosion in Blues floodplain
sediments in WW valley
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Walla Walla River Floodplain
Note Horse Heaven Hills- anticline of folded CRBs
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Surface geological units
Note old WWVA boundaries- pre-2000 vineyards are
in black Strong correlation between units and
elevation (also climate) Basalts at highest
elevations and where erosion exposes them Loess
at higher elevations than slackwater deposits
(north and on Blues-Horse Heaven Hills)- mostly
silt Slackwater deposits mostly sand and silt in
WWVA Loess and slackwater silts are glacial-
derived from Canada- qtz-feldspar..not
basaltic Floodplain at lowest elevation-locally
cobbles, gravel, sand, silt, clay- highly variable
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Soil textural classes
WW very low in clay except in some areas of the
WW River floodplain
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Soil Types
75 soil types in WW Soil Survey, can lump into
8 groups (remember strong elevation-rainfall
gradient too) 1- Cobble-loam-silt of floodplains
and terraces of WW River and tributaries long
used for orchards- most vineyards now on the
terraces with thin loess Well-drained, and low
organics- permits good control of grape vigor by
management of water and nutrients 2- Loamy to
silty in same floodplain-terrace
areas Poorly-drained, saline and alkaline- good
for onions- Three Rivers on a well-drained
terrace close to these 3- Loess over slackwater
deposits on dissected terraces and
uplands Well-drained and silty Woodward Canyon
Vineyard Where loess thin (lt60 cm) and low
elevation cost of water may be a problem 4-
Similar to 3- Loess over slackwater on dissected
terraces Silty, uniform, low to mod organic
matter- extensive vineyards 5- Excessively
drained sandy soils of dunes with lt 30 cm/yr rain
some juice grapes 6- Silty soils of deep loess
on uplands 20-38 cm/yr rainfall 7- Silty soils of
deep loess on uplands 38-58 cm/yr rainfall- more
organics 8- Loamy to cobbly well-drained soils on
steep mountain slopes- Figgins Mill Creek Upland
Vineyard is only one yet
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Wind and rainfall patterns
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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SW-NE Cross Section
WW vineyards on four fundamentally different
substrates slackwater terrace, loess, river
gravel, and floodplain silt Majority are in
loess, either thick over basalt or thin over
slackwater silts (which in turn are on
basalt) Again, well-drained silts with low
organics allow the vintner to manage moisture and
nutrients Overly fertile floodplain soils develop
strong vegetal flavors Good slopes allow good
airflow too- colder air sinks away so fewer frost
problems Cristophe Barons Caillouxe searched
with Kevin Pogue for very cobbly floodplain area-
Forces roots deep, heated cobbles radiate,
calcic soils stress vines combine to -gt very
concentrated fruit
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Some Examples
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Examples
Pepper Bridge cabernet on thin loess
Vineyard-covered island of slackwater deposits
on WW River floodplain
Cottonwood Creek vineyard chardonnay grapes on
floodplain silts over gravel
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Examples
Caillouxe vineyard syrah on floodplain gravels. E
shows trench and deep roots.
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.
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Examples
Generalizations Low-precipitation during growing
season, low organics, well-drained silts allows
the vintner to control moisture and nutrients to
develop vigor and complexity (and yield) Highest
quality vineyards lower their yield to 2-3
tons/acre (compared to 4-5 ton statewide
average) W E variation in elevation
rainfall, plus variations in soils, drainage,
organic content, water table level of loess,
slackwater deposits, floodplain Rich diversity
of Terroirs Latitude affects summer sunlight and
temperatures (day and night) Unique geological
and soil features in WW suggest that our wines
may develop flavor and quality characteristics
that set them apart from other wine-producing
areas
Seven Hills on 2 meters of loess (over slackwater
deposits)
Canyon-bottom floodplain soils are better for
fruity wines, such as Biscuit Ridge
Gewurtztraminer)
Mill Creek Upland vineyard tries out the
higher-elevation loess
From Meinert and Busacca, 2000. Geoscience
Canada, 27, 149-170.