Giant Floods, Channeled Scablands, and Kalapuya Legend
When Ice Age glaciers blocked the Columbia River, the Spokane River and the Clark Fork river in Montana they
formed Glacial Lake Columbia, Glacial Lake Spokane and Glacial Lake Missoula. The evidence of these lakes
can be seen in the lakebeds visible in various road cuts in eastern Washington and lap marks on hills and gravel
deposits in Montana. Glacial Lake Missoula, the largest lake, covered some 3000 square miles and was about
2000 feet deep (Figure 1).
Figure 1. Glacial Lake Missoula in light blue, flood extent in gray, and
channeled scablands of southeastern Washington.
J. Harlen Bretz, in numerous publications between 1923 and 1969, drew attention to the large scale flood origin of
the Channeled Scabland region on the Columbia Plateau of southeastern Washington. His early papers found
little favor and the flood hypothesis won general acceptance only after a contest with a variety of hypotheses
more in accord with uniformitarian principles. [Uniformitarian Principle: a concept proposing that all geological features
were formed just as features are formed today. Sudden events like volcanoes, earthquakes, floods and asteroid hits are not to
be considered when describing how features are formed. Also, uniformitarianism]. This contest lasted nearly forty years.
The principal obstacle to acceptance of Bretz's hypothesis was the lack of any evident source for the immense
quantities of water required, an objection only removed when the volume and rate of emptying of ice-dammed
Lake Missoula was shown to be adequate. Two of Bretz's later papers clearly illustrate the erosional and
depositional features that resulted from Lake Missoula's outbreak flood.
At some time the ice dam blocking the Clark Fork broke, sending nearly 500 cubic miles of water across northern
Idaho's Rathdrum Prairie and into eastern Washington. At 45 miles an hour and 10 times the flow of all the rivers
in the world today, the raging floodwaters swept into the Spokane Valley and out across the loess-covered basalt
plateau. [Loess: fine dirt deposited by wind usually from arid or glaciated areas. Basalt: volcanic rock caused by partial
melting of the Earth's crust]. Turbulent, powerful currents eroded the basalt, tearing out whole columns, eroding the
loess and scouring the landscape.
Separated into three huge flows up to 600 feet deep, the torrents carved the 20 mile-wide Cheney-Palouse Tract,
the 14 mile-wide Crab Creek Channel, and the 50 mile long Grand Coulee. As you can see on Figure 2, the
waters created numerous cross channels. The flow is from upper right to lower left. In this LANDSAT satellite
view of the area you can plainly see the darker channels and lighter islands of the channeled scablands. The
very dark areas are various lakes and rivers.
Blocked by the Horse Heaven Hills on the west and the Blue Mountains to the south the water raced to the Walula
Gap (Figure 1) where the Columbia River heads west to the Pacific Ocean. Unable to flow out the narrow gap as
fast as it came in, the flood waters were pushed back and reversed the flow of the Snake River all the way past
Lewiston, Idaho. Temporary lakes formed in the scablands and silt, sand, and gravel settled out of the water.
Eventually the water drained down to the Pacific and along the way flooded Oregon's Willamette Valley. Portland,
Oregon, would have been under 400 feet of water at this time.
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Figure 2. Channeled Scablands of southeastern Washington.
Geological evidence indicates that 89 or more such floods happened over the years as the ice dam blocked the
Clark Fork, broke and re-blocked the river's flow. There is some evidence that Moses Coulee to the west of
Grand Coulee was formed before Grand Coulee as an earlier ice dam blocked the Columbia River and a flood
channel was carved just east of Wenatchee, Washington.
So where did all the loess, dirt, sand, gravel and silt end up? Some of the material was deposited in the
Willamette Valley in Oregon. Ice rafts even brought very large boulders downstream and as the rafts melted left
them in the valley. Core samples from the Escanaba Trough just off the coast of California show that there were
at least 12 major floods that were large enough to carry material down the Cascadia Channel and into the trough
(Figure 3). Other deposits have been found in the Astoria Channel.
Figure 3. Pacific Northwest ocean trenches.
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Fresh water is usually less dense than sea water and stays on the surface where rivers flow into the ocean.
When the river water is very cold and is carrying lots of material, as when the Ice Age floods occurred, the fresh
water pushes down and under the sea water and follows channels on the ocean floor. Geologists call these flows
turbidity currents. At the time of the floods the oceans were about 100 meters lower due to the amount of water
frozen in glaciers and ice sheets covering the land. This allowed the turbidity currents to flow into the off shore
channels more freely. It is thought that the majority of the material removed from eastern Washington is now in
these channels.
Was anyone around to witness these phenomenal floods? There is no direct evidence, but there are Native
American legends that seem to indicate someone saw and passed on the story of huge floods. The Kalapuya
tribe, from the central Willamette Valley of Oregon, has a legend recounting a flood that forced all the people up
onto a large mountain. The legend was recorded in the book “Santiam Kalapuya Myth Texts” and published in
1945 by Melville Jacobs. His ethnographic research for myths was conducted in 1928 with one native speaker of
the Kalapuya dialect:
Now the water (flood) came up (rose). And some of the people, the large birds carried them (up)
on their backs. They took them to a big mountain (Pike’s Peak or Mary’s Peak, west of Corvallis).
All those people went to that big mountain there. Now the water was coming up higher. All the
country was filled with water. (2) Then skunk took an oak puff ball (i.e. an oak gall), and he made a
hole in the oak puff ball, he got inside that. And to be sure that oak puff ball floated on the top of
the water. Now all the people were running along, they climbed up the big mountain. Now it was
on that one very loftiest mountain, then all those people got (up) to there. (3) And copperhead
snake was carrying the fire along as he swam. Now the water pretty nearly got to the top of the
mountain. Then those people said to panther, “What have you taken? This water does not want to
go back (to recede).” And so he said, “I took nothing, I took only my child, and I took that woman’s
hair.” (4) “Oh,” the people said, “Throw away that hair of hers. Maybe it is that which is pursuing.”
So panther told him, “Throw that hair into the water.” Sure enough small chicken hawk threw the
hair into the water, and to be sure the water went down then, it went back (receded).
This legend does have some pretty striking similarities to what the Missoula flood may have looked like in
the Willamette Valley, except for the idea that it almost reached the top of Marys Peak, which is almost
3,500 feet above the valley floor (Figure 4).
Figure 4. Marys Peak from the Willamette Valley.
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