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SOPHIA OF WISDOM III - GRAND COULEE DAM 04
THE LIBRARY OF SOPHIA OF WISDOM III
THE SOPHIA OF ALL SOPHIA OF WISDOMS
AKA CAROLINE E. KENNEDY________________________
OCTOBER 26, 2006
GRAND COULEE DAM 4 - ICE AGE FLOOD THEORY
Ice Age Floods
Study
of Alternatives
Section D—Background
s u m m a r y
This section presents a brief overview of the
Glacial Lake Missoula Floods story, two of the key people involved with discovering the Floods and the glacial lake from which
the Floods originated, and events that led up to the initiation of the Ice Age Floods Alternatives Study.
1. Geologic
Background
In recent geological history, portions of the United States have been the site of several massive flooding
events caused by the abrupt drainage of glacial lakes. The most dramatic of these events are the Ice Age Floods that covered
parts of Montana, Idaho, Washington, and Oregon. For a better understanding of the Floods, perhaps a good place to start is
to first look at the geological and climatic changes that led up to these cataclysmic floods.
Today’s
travelers to the Northwest are witnesses to a story that puzzled geologists for years. (NPS Photo)
Generally accepted
scientific evidence indicates that the earth is around 4.5 to 4.6 billion years old. Glaciation can be traced all the way
back to the Proterozoic Era, approximately 2.3 billion years ago, when the earth was covered with ice. Near the end of the
Proterozoic Era, between 850 and 600 million years ago, rock records indicate another global glaciation period.
About
200 million years ago the Atlantic Ocean began to open up and the continents drifted into their current configuration. The
dinosaurs became extinct 65 million years ago, and about 20 million years ago, in late Cenozoic Era, the Pacific Northwest
started to look much as it does today, with its mountains, valleys, and shorelines.
Ice Ages have occurred sporadically
throughout the earth’s history, although they represent a relatively small part of geologic time. Many of the still
visible effects of the great ice sheets that periodically covered parts of North America were produced during the last Ice
Age, in the Pleistocene Epoch. These ice sheets left a distinctive geologic record in the land forms of the Northwest.
Floods
of molten lava poured across western Idaho, eastern Washington, and northern Oregon. (NPS Photo)
From 17 to 13 million
years ago, lava flows emanating from a series of volcanic extrusions spread across the Columbia River Basin, constructing
a broad lava platform across northeast Oregon, eastern Washington, and central Idaho. These extrusions were among the largest
and most spectacular lava flows of their kind. The Columbia River basalts that flooded across the Pacific Northwest consisted
of more than 42,000 cubic miles of lava. In places, the basalt is more than two miles thick. In the Columbia Basin, the lava
basalts were covered with windblown glacial dust and silt, called loess, that is up to 250 feet thick. The Cascade Mountains
were formed during the later part of these basalt extrusions.
During the Pleistocene Epoch Ice Age, beginning about
2.5 million years ago, virtually all of southwestern Canada was repeatedly glaciated by ice sheets that also covered much
of Alaska, northern Washington, Idaho, Montana, and the rest of northern United States. In North America, the most recent
glacial event is the Wisconsin glaciation, which began about 80,000 years ago and ended around 10,000 years ago. Floods events
from this last glacial period are the subject of this report.
2. Story of the Floods
At the end of the last
Ice Age, a finger of the Cordilleran ice sheet crept southward into the Idaho panhandle, forming a large ice dam that blocked
the mouth of the Clark Fork River, creating a massive lake 2000 feet deep and containing more than 500 cubic miles of water.
Glacial Lake Missoula stretched eastward for some 200 miles and contained more water than Lake Erie and Lake Ontario combined.
When the highest of these ice dams failed, lake water burst through, shooting out at a rate 10 times the combined flow of
all the rivers of the world.
This towering mass of water and ice literally shook the ground as it thundered toward
the Pacific Ocean, stripping away hundreds of feet of soil and cutting deep canyons—”coulees”—into
the underlying bedrock. With flood speeds approaching 65 miles per hour, the lake would have drained in as little as 48 hours.
Over time the Cordilleran ice sheet continued moving south and blocked the Clark Fork River again and again, recreating
Glacial Lake Missoula. Over approximately 2,500 years, the lake, ice dam and flooding sequence was repeated dozens of times,
leaving a lasting mark on the landscape.
Today we can see how the floods impacted the landscape. They carved out more
than 50 cubic miles of earth, piled mountains of gravel 30 stories high, created giant ripple marks the height of three-story
buildings, and scattered 200-ton boulders from the Rockies to the Willamette Valley. Grand Coulee, Dry Falls, Palouse Falls—all
were created by these flood waters, as were the Missoula and Spokane ground-water resources, numerous wetlands and the fertile
Willamette Valley and Quincy Basin.
Glacial Lake Missoula contained more than 500 cubic miles of water. (Image:
J. Tindall, B. Pettus, J. Sipes)
During the last Ice Age, a finger of the Cordilleran ice sheet crept southward
into the Idaho Panhandle, damming the Clark Fork River and creating Glacial Lake Missoula. At its maximum, Glacial Lake Missoula
contained more than 500 cubic miles of water and was 2,000 feet deep behind the ice dam.
About 17,000
years ago the ice dam broke numerous times, with the initial outburst releasing a torrent of water that flowed toward the
Pacific Ocean at a rate of 10 times the combined flow of all the rivers of the world.
As the flood waters
thundered toward the ocean, they stripped away thick soils, cut deep canyons in the underlying bedrock, and scattered house-sized
boulders across four states.
Unable to pass through a narrow gap near Kalama, Washington, the flood water
backed up and flooded the Willamette Valley, Oregon.
More than 16,000 square miles of land were flooded in
the first-of-many Glacial Lake Missoula floods.
Today, geologists and visitors to the region can see first
hand the varied flood features created by the Ice Age Floods.
(Art and photography courtesy OPB (J. Tindall, B. Pettus,
J. Sipes) and NPS)
3. J Harlen Bretz—Hypothesis of Catastrophic Floods
In many ways, the story of
the Floods is also the story of J Harlen Bretz (1882-1981), who proposed the theory that the Channeled Scablands of eastern
Washington, and much of the Northwest as we know it today, were formed by catastrophic flooding.
J Harlen Bretz
(1882–1981)
(1949 photo by Dr. Julian Goldsmith)
Bretz became a high-school biology teacher in Seattle.
He had earlier developed a keen interest in the glacial geology of the Puget Sound and had studied the area extensively. This
interest in geology led him to the University of Chicago, where he was awarded a Ph.D. in Geology in 1913. Then, Bretz accepted
a position as an assistant professor of geology at the University of Washington and later at the University of Chicago. His
thesis was on the glacial history of the Puget Sound, and he quickly became recognized as an expert in the features of stream
and glacial erosion.
Bretz began his field research in the Channeled Scablands of central Washington during the summer
of 1922, and it quickly became clear to him that neither glaciation nor ordinary stream erosion explained the Scablands. The
following year Bretz made his two presentations to the Geological Society of America on the Scablands. The first paper provided
a detailed physiographic description of the Scablands; the second suggested that it would have taken a massive volume of water
to create the degree of channel erosion that had occurred.
Bretz’s second paper on the Scablands also discussed
the mounded gravel deposits that were scattered throughout the area. He proposed the idea of a catastrophic flood and included
the first detailed geological map that included all of the Scablands and showed the extent of the floods. Bretz used the name
“Spokane Flood” because he assumed the source of the water for this flood was somewhere near Spokane, Washington.
Columnar basalt at Frenchman Coulee in eastern Washington (NPS Photo)
Bretz was confident that a flood
had occurred, but was unable to figure out where the water had come from. Originally, he proposed that the water was the result
of increased runoff from melting glaciers. But even Bretz had a tough time imagining any significant volume of water melting
rapidly enough to have such devastating impact. Not until 1930 did Bretz consider Glacial Lake Missoula as the possible source
of water he was searching for. But the geologic evidence was elusive, and he did not fully embrace the idea until 1956. Unable
to provide a clear, scientific argument for the source of flood water, Bretz went on to other activities.
Bretz lived
to the age of 98 and late in life had the satisfaction of seeing his theories validated. Perhaps it is poetic justice that
in 1979, Bretz, at the age of 96, received the Penrose Medal, the Geological Society of America’s (GSA) highest award.
J Harlen Bretz spent more than four decades defending his theories on the Spokane Floods before they were
generally accepted by the scientific community.
—John Allen and Marjorie Burns, Cataclysms of the Columbia
Aerial
view of Dry Falls cataract, Grand Coulee, Washington, looking north. (NPS Photo)
Bretz knew that the very
idea of catastrophic flooding would threaten and anger the geological community.
—Andrew Macrae, University
of Calgary, Department of Geology & Geophysics
4. Joseph T. Pardee—Glacial Lake Missoula
Joseph
Thomas Pardee (1871–1960) also played a key role in understanding the story of the Floods. It was Pardee who proposed
that the floods Bretz talked about occurred when the ice dam that had formed Glacial Lake Missoula was breached.
In
his numerous reports, Bretz rarely asked about a water source, and then only in a brief sentence or two devoid of analysis.
Richard Waitt, USGS
“I know where Bretz’s Flood came from.”
J. T. Pardee, at
a 1927 meeting of the Geologic Society in Washington DC
Pardee, a geologist with the U.S. Geological Survey, began
studying the Scabland region near Spokane, Washington, and the intermountain basins of Montana in 1910. Pardee found geomorphic
evidence of a large glacial lake in western Montana; strandlines (high water marks) indicating the maximum height of the lake
are clearly visible today in the area around the city of Missoula, Montana.
Pardee spent years collecting, analyzing,
and documenting other geomorphic evidence, and eventually the scientific community was convinced that Glacial Lake Missoula
had indeed existed.
Apparently Pardee and Bretz did communicate over the years, and Pardee suggested that Bretz consider
the draining of Glacial Lake Missoula as a possible source of the Floods. But neither Pardee nor Bretz had the scientific
evidence to back up such an idea.
Later, in the late 1930s at Camas Prairie in northwestern Montana, Pardee discovered
a series of ripple marks left on the lake bottom sediments of Glacial Lake Missoula that could only have been formed by powerful
currents that flowed over the bottom, shaping the sediments into smooth, parallel ridge-rows. The marks were evidence that
the ice dam holding back the water had failed suddenly, and Glacial Lake Missoula had drained rapidly. The ripple marks are
up to 50 feet high and 500 feet apart. Because the ripples are so large, it was only when Pardee was able to view these unique
features from the air that he recognized them as being formed by water. Once they had been identified and people knew what
to look for, similar examples of giant ripple marks were found throughout the path of the floods.
Giant ripple
marks can still be seen clearly in Camas Prairie, Montana. (NPS Photo)
In addition to the ripple marks, Pardee found
other evidence of the ice dam failure, including severely scoured constrictions in the lake basin and huge bars of current-transported
debris.
Pardee first presented this evidence in 1940 at a meeting of the American Association for the Advancement
of Science in Seattle, Washington. His conclusions were later published in the 1942 GSA Bulletin paper titled “Unusual
Currents in Glacial Lake Missoula.” Collectively, these papers played a pivotal role in the scientific community’s
eventual acceptance of the cataclysmic flooding hypothesis. His work provided, for the first time, a logical source of water
needed to support Bretz’s hypothesis. The ripple marks were a key piece of evidence that eventually helped convince
skeptics of the cataclysmic-flood hypothesis.
Even after Pardee’s work was made public, acceptance of Bretz’s
theories was slow in coming. It took another 20 to 30 years before Bretz’s theory of catastrophic flooding became generally
accepted among geologists.
Pardee and Bretz were certainly not the only ones involved in solving the mysteries of
the Glacial Lake Missoula Floods. For example, in 1871, geologist Thomas Condon proposed the idea that Oregon’s Willamette
Valley was flooded sometime during the Ice Ages.
5. Scientific Debates—Uniformitarianism vs. Catastrophism
Wave-cut strandlines cut into the slope at left in photo. These cuts record former high-water lines, or shorelines
of Glacial Lake Missoula near Missoula, Montana. Gullies above the highway are the result of modern-day erosion. (NPS Photo)
The debate over the origin of the Channeled Scabland region of eastern Washington was one of the great controversies
in the history of geology. One reason Bretz encountered such vehement opposition to his hypothesis of catastrophic flooding
was that there were no records of such floods in modern-day experience and the magnitude of the floods was at a scale that
was difficult to imagine. The biggest difficulty, however, was that a catastrophic flood at the scale Bretz was describing
was almost biblical in proportion, and this notion was directly at odds with the idea of Uniformitarianism.
“They
were all loaded for me and after letting me talk for two hours they opened fire.”
—Bretz, after a 1927
meeting of the Geologic Society in Washington DC
It is usually interpreted as a contest of ideas between neocatastrophist
Bretz and a platoon of diehard gradualists, an image Bretz himself promoted... .
—Richard Waitt, USGS
James
Hutton, a Scottish geol
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