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Pacific Northwest
Dry Falls
Description
Geological History
Location
Getting There
Links
Visitor Center
Driving tour
to Dry Falls (includes map)
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 As
the name suggests, Dry Falls no longer carries water, but is the remnant of
what was once the largest waterfall known to have existed on earth.
Viewing the 3.5 miles of sheer cliffs that drop 400 feet, it is easy to imagine the roar of water
pouring over them. (Niagara Falls by comparison, is one mile wide with
a drop of 165 feet).
Description
The
falls were created following the catastrophic collapse of an enormous
ice-dam holding back the waters of what has been named "Glacier
Lake Missoula". Water covering three thousand square miles of northwest
Montana, about the
volume of Lake Ontario, was locked behind this glacial
dam until the rising lake penetrated, lifted and then blew out the ice dam. The
massive torrent (known as the Missoula Flood)
ran wild through the
Idaho panhandle, the Spokane River Valley, much of eastern Washington
and into Oregon, flooding the area that is now the city of Portland under
400 feet of
water.
Reaching the Dry
Falls area, this tremendous force swept away earth and rock from a
precipice actually 15 miles south of the falls near Soap Lake, causing the falls to
retreat to its present position, now known as Dry Falls. The falls is
said to be a spectacular
example of "headward erosion". If this is confusing, given the present topography,
it also helps to know the falls are on an ancient course of the Columbia
River. The river had been diverted this way by the encroaching
glaciers. It returned to its present course as the ice retreated.
Geological
History
The Channeled Scablands were created in the Columbia Plateau by
cataclysmic Ice Age Floods, including the one described above, between
10,000 and 15,000 years ago. The floods occurred about every 50 years and lasted a few days to a few
weeks, leaving a deeply scarred plateau.
This explanation for the strange land formations we see today was first put
forward by J. Harlen Bretz in the 1920s. It took more than 40 years for the
geological community to accept that such dramatic changes could take place
in a matter of days or weeks.
The landscape we see today is one with
hundreds of small lakes,
flat-top mountains, and canyons known as "coulees" (ravines and ancient
basins of waterfalls, some still holding water). All have been left several hundred feet above the present course of the Columbia
River. Grand Coulee Canyon, at 50 miles in length, and 1 to 5 miles across, is the
largest of the channels gouged by a deluge.
The raw material so ferociously
sculpted by the floodwaters is basalt. It is actually a black rock,
yet you are presented
with a landscape of rusty browns, as a result of the iron oxidizing in the
exposed rock. In places the browns are highlighted by yellow lichen. The geometrical basalt
shapes, in the form of blocks and pinnacles
and columns were exposed but not carved by the flood waters. Rather,
they formed as basalt lava cooled into rock.
Prior to the floods, between about
17- and 6 million years ago, the basalt was laid down in successive lava
flows that engulfed parts of Washington, Oregon and Idaho, gradually
filling valleys and covering hills. In places it became more than two
miles thick. Some even streamed all the way to the Pacific
Ocean. Nature certainly wasn't restrained in this region! The
lava field became the second biggest in the world, covering over one hundred
thousand square miles, and is now known as the Columbia
Plateau. The "high
desert" plateau with its exposed lava formations dominates central,
inland Pacific Northwest.
Location
Located 7 miles southwest of Coulee City in northeast Washington. It
is a feature of Grand Coulee Canyon, which is itself part of the Channeled
Scablands that cover three-quarters of eastern Washington.
Visitor Center
Dry Falls Interpretive Center.
Sun Lakes State Park, Coulee City, WA 99115. Phone: 509-632-5214
Sun Lakes-Dry Falls
State Park is a 4,027-acre camping park with 73,640 feet of freshwater
shoreline at the foot of Dry Falls. The Dry Falls Interpretive Center
is located two miles north of the main park on
Highway 17. Summer hours are from May 1 through September 30th
from 9 a.m. to 6 p.m. daily; Winter hours are frm October 1 through April
30th from 9 a.m. to 5 p.m. - closed Thurdsays. Admission is
by donation.
Getting to
Dry Falls
Turn
south of US-2 onto WA-17, and drive to
the visitor center which is in sight of the highway, on the east side.
Related Links
The
Missoula Floods
Nicely designed and very informative site describing the awesome process by
which the Scablands were formed by the Missoula Floods. Visuals
include a video animation of the flood. (Produced by Jim Newman for Oregon
Public Broadcasting.)
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