2005 Recreational Geology Field Trip
Geology and the Upper Columbia Terroir
Kettle Falls, Washington
October 8, 2005
William Swartz hanshan@plix.com
Early October is a glorious time.
Autumn colors are at their prime. Geologists are not antagonistic to plants,
but less, green foliage does make the physical landscape easier to visualize.
It is harvest time, and time for grape pressing.
The baseline for wine production is a Mediterranean climate: warm, dry growing
seasons and cool, moist dormant periods (the growing season is winter, in Central
Chile and Southwest Australia). Northeast Washington frequently receives the
necessary 2,000 hours of sunshine, necessary to mature grapes. Summer drought
allows the viticulturist to control water quantity and timing, to achieve maximum
sugar content. Winter temperatures seldom fall below –20°C, the point
of damage to vines.
Three geological factors lend special character to the Upper Columbia Region,
as a terroir for premium wines. First or deepest, a wide variety of rock
types as the parent material for the soils. The differing chemical balances
produce site-specific flavors, across any grape variety. Many classic wine regions
are distinctive for their geology: limestone in Bordeaux, volcanic in Burgundy,
granitic in Champagne. Second in the soil, volcanic ash gives soil exceptional
properties. The ash particles are pumice, the frozen froth of magma. The individual
grains are fragments of glass bubbles. Countless, microscopic edges are sites
for chemical reactions and holding moisture. Washington wine regions are unique
for the tephra content of their soils. Third at the surface, the particular
glacial history of the Upper Columbia Valley provides a unique situation. In
the receding phase of continental glaciation (24,000- 16,000 years before present),
a tongue of ice occupied the Valley. The top of the glacial tongue was about
600M elevation, at the latitude of Kettle falls. Melt water coursed along the
sides of the glacier, depositing silt, sand and gravel, in terraces. As the
glacier melted, the ice vacated the center of the Valley. Without support, the
terraces tilted, toward the axis. A gentle slope, across the terraces, allows
cold air drainage in the Spring and Fall. A few days of freedom from frost,
in the cool seasons, provide the sort of challenging conditions that develop
distinctive flavor.
 |
REGIONAL GEOLOGY Toothed line =
Thrust fault |
Road Log
Mileage
0.1 Start east on US 395 From Barney’s Junction, 395 and WA 20, west of
Kettle Falls
Take the opportunity to get a close look at the outcrops of amphibolite gneiss,
particularly the railroad cut, just north of the junction. This layer slopes,
from here to a depth of eleven kilometers, beneath Colville. You are looking
at the
horizon of transition, from brittle to ductile deformation, when crustal-scale
plated slid
apart, about 47 million years ago (47Ma).
0.2 Cross the Columbia River, Lake Franklin D Roosevelt.
1.6 This surface, east to Kettle Falls and south to the Colville River, is covered
with loess.
Very fine sand was blown into dunes, while glacial ice was still present and
glacial lakes
were absent.
2.8 Turn right (south) on Washington 25
4.5 The “popcorn” texture of the cut surfaces, near the top of the
grade, shows the presence
of bentonite clay. That clay forms after volcanic ash falls into lake waters.
5.0 The layers of coarse and fine gravel record the top surface of bars, on
the inside of a
stream bend.
5.5 Cross the Colville River
7.4 Stop 1: Park in the turn out, overlooking Rickey Point. On the east side
are outcrops of
Metaline Formation meta-limestone. The original lime mud was deposited on the
near,
continental shelf in Middle to Late Cambrian time. What were thin inter-beds
of mud have
been distorted and converted to metamorphic minerals. Across the Lake are bright
bluffs
of the Reed Terrace Landslide. A multiple alcove landslide was triggered by
a wet Spring
Road log, continued:
7.4 and filling of the reservoir. 135 million cubic meters of material slid,
into the Lake in
May 1953.
8.2 We are crossing one of the sloping terraces. Mingo Mountain casts too much
shade
for vineyards; however, it is ideal for orchards. The terrace material covers
the crustal
scale thrust fault, separating the Kootenay Terrane from the Covada Terrane.
11.8 Stop 2: Park in the right hand turnout, at the end of the guardrail. The
outcrops are
of Covada Group meta-sediments. These rocks are contemporary with the latest
of the
Metaline Formation and younger rocks of the Kootenay Terrane. The difference
being that
Covada were deposited with and from volcanic rock, in a deep ocean setting.
The dark
colors and high iron content are typical of that environment. Metamorphism has
obliterated the structures of sub-marine mud flows, but the nodules of pyrite
record the
oxygen starved conditions.
12.7 The high road cuts expose an assemblage of lava, volcanic breccia, chert
and minerals
exhaled from sub-marine hot springs.
17.8 Rice, Washington
18.0 Cross Cheweka Creek
18.1 Stop 3: Turn left into the first, driveway, past the creek. Neanderthal
Vineyard
18.3 Return north on WA 25
21.5 We are crossing Chalk Grade Flat. This terrace did not collapse, as it
is supported by
a bedrock rib, visible at the west edge. The air drainage is poor, but the deep
soil suits
the shade tree nursery. The prominent, white hill, seen straight ahead, is The
Split-off.
It is a reef of high purity limestone, within the Covada Group. A mile beyond
it are the
Acme-Dora and Alma Mines.
22.9 Stop 4: Turn right, into the drive, the top of the grade. Barreca Vineyard.
23.0 Continue north on WA 25.
33.1 Turn right, east on Old Kettle Falls Highway.
33.8 Turn right at the 4-way stop, onto Greenwood Loop.
34.3 Stop 5 Park at the Meyers Falls Interpretive Site. The Falls cascade over
andesite lava
rock of the Sanpoil Volcanic Formation. The Sanpoil lavas tuffs and breccias
erupted as
the continent was being stretched, in the Middle Eocene epoch. Magma extruded,
along
fissures at the edges of separating plates of the crust. These rocks, and related
granites,
provide a granitic component to soils. Return by Greenwood Loop.
34.8 Turn right at the 4-way stop and bear left on Meyers Street.
35.5 Junction with US 395. Conveniences are available at Exxon. Proceed west
on 395.
36.4 Singer’s Junction. Turn right, north on WA 25.
36.9 The silty, ash-rich mudstone provides poor road base. The next mile of
road is plagued
by repeated slumping.
36.9 The thin beds of mudstone, each represent a season in the ice-marginal
lakes. The thin
layers record normal or cool years. The thicker layers result from flood years.
40.4 Stop 6, Turn into the small parking spot, on the left, before Pingston
Creek. Extra cars
may use the next turn-out to the south. Beach access and glacial sediments.
These
banks display several sedimentary structures, including channel fills, foreset
beds and
surge cross-bedding. One horizon contains clay-stone concretions. Three hundred
meters, to the south, the highway cut exposes the chloritic breccia, along the
Kettle
Dome Detachment Fault. Return south on WA 25.
Road log, continued:
41.6 The high road cut exposes Permian rocks of the Slide Mountain Terrane.
The bulk
of these rocks are greywacke, altered mud rocks from the offshore prism above
a
subduction zone. The prominent white band is a dike of meta-carbonitite. The
magma
was mostly calcium and potassium carbonate. Silica poor magmas are usually
associated with rifting events.
43.0 Turn right, west at junction with US395.
45.8 Remain on US 395 at junction with WA 20.
46.7 The mica quartzite is as highly altered and deformed as the amphibolite,
but the
changes are localized to the former muddy interbeds. This rock forms the brink
of the
Kettle Falls.
49.1 Turn right onto Northport-Flat Creek Road.
49.2 Cross the Kettle River
49.3 Stop 7: Turn left into Kamloops Island Campground. This is the last rest
stop for the
remaining twenty-three miles. The island offers a close look at the quartzite
and the
exposures, across the River.
49.7 Continue left, north, on Northport-Flat Creek Road.
51.0 This terrace has remained fairly level through repeated episodes of collapse
and
re-covering with later sediment.
53.6 There are good views, across the reservoir, to the US Gypsum Quarries.
The Permian
meta-limestone was burned in a wood fired kiln to produce agricultural and chemical
lime.
57.7 Stop 8: Park in the alcove, on the left, south of the high, gray cut. The
protozoan
fossils, in this meta-limestone, indicate a late Permian (Guadalupan) age and
have s
species affinity to fossils from McCloud River, California, as well as from
Japan. These
large blocks are set in a matrix of argillite, but do not have reef structures.
62.1 The spectacular outcrops are part of 5,500 meters thickness of dolomite
marble. This
was Cambrian North America’s equivalent to the Great Barrier Reef. More
than a million
tons of the rock has been mined, at the Don Grubb Quarry. Most of the product
was used
for decorative stone, stucco aggregate, and paper or plastic filler. The white
gravel
driveways are from that quarry.
64.0 Take careful look at the cliff, to the west of the river and straight-ahead.
Note the curving
rock layers, near the top. This is part of a pair of folds, in the Maitlen Formation
rocks.
The fold limbs are pressed into parallel, and the whole set is turned completely
up-side
Down.
67.3 We can look to the left, to see views of Flat Creek and Crown Creek valleys.
Faults
trace the valleys. The fault block ridges are in turn: a more distant terrane
of sedimentary
rocks, a Jurassic sea floor spreading sequence, and the Sanpoil volcanic rocks.
70.2 The double quarry, in the right distance, is in the limestone of the Metaline
Formation.
Its product was raw material for a cement plant, near Spokane.
70.7 Turn right on Vineyard Way. This is a long, rough, unimproved road.
72.3 Stop 9: China Bend Vineyards. This is the final stop. Enjoy the wines,
and walk around
to explore. Thanks for joining us.