On earth 4.5 million years ago all water was frozen and the surface of the earth was a frozen ball, and the moon was not yet separated from the earth by a gigantic celestial collision. As the sun above and heat of compression below began to warm the crust, most ice melted, oceans were formed and the super continent Pangea emerged from it's frozen grave. All continents today were part of Pangea, the super continent.
Deep in the earth lie movable plates called techtonic plates, and all continents rest on them.
As continents separated from Pangea, Africa and Asia did not move far, but north and south america moved far to the west.
South America separated from Africa and moved several inches a year to it's present location.
North America left Pangea where Denmark is now, and moved in a east-west orientation several inches a year until Mexico hit the Pacific Plate. At that point North America rotated into a north-south orientation until it hit the Asian Plate at which time Alaska snugged up against Siberia, and the Aleutian Islands snugged up against the Kamchatka Peninsula of Russia.
While all this was going on, the northern part of the world went through several ice ages, the last starting long ago and ended about 20,000 years BC when the earth began to warm again, and glaciers and ice sheets began to retreat. But Alaska, once a steaming tropical paradise, inhabited by dynosaurs and other ancient animals, remained cold. The forests were turned over and submerged deeply where the vegitation eventually turned into oil.
12,000 years ago western Montana was bottom of a lake 2,000 feet deep now known as Lake Missoula. This lake was formed by melt of the Cordilleran ice sheet. But part of the ice sheet a mile thick dammed up the Clark Fork River where it was entering Idaho. When the water of the lake got deep enough, it burst through the dam to devistate Idaho (see the scoured flat area on the map west of Missoula Lake), eastern Washington, and down the Columbia river region of Oregon to the sea.
Above edited photo of Lake Pend Oreille near Sand Point Idaho.
They say that the east end of this 1,000 foot deep lake was involved with Lake Missoula which spawned the mega floods as the ice sheets retreated. The Cordilleran ice sheet at this point was 5,000 feet deep and actually overtopped the mountains around this lake.
Lake Pend Oreille was formed during the ice age. It is also believed that the eastern side of the lake was in the path of the ancient Missoula Flood. The lake sits at the south end of the Purcell Trench, carved by glaciers moving south from Canada. The eastern side of the glacier is believed to have formed the dam for the Missoula flood, at the point where the Clark Fork river enters the lake between the Cabinet and Bitteroot mountains.
The area around the Lake is the traditional home of the Kalispell Indian peoples. David Thompson established a Northwest Company trading post on the lake in 1809. A French Canadian fur trader on Thompson's party is believed to have given the lake its name. The words "Pend Oreille" are French for an ear-hanging or pendant. Ear pendants were characteristic of the Kalispell tribe. The lake is shaped much like a human ear when viewed from above or on a map.
The mega floods:
The flood hundreds of feet deep tore away soils and mountainsides, leaving giant ripple marks, the scablands of eastern Washington and carved out the Columbia River Gorge. Over time, Glacial Lake Missoula filled and emptied in repeated cycles, leaving its actions embedded on the land.
At Portland Oregon the cascade scoured the east slope and overtopped 400 foot high Kelly's Butte. Much of the water turned south and rushed up what is now the Willamette River as far as Eugene, Oregon, flooding the Tualatin valley and devistating both sides of the lowlands along the I-5 corridor for over a hundred miles.
By all investigative accounts there were no people in America when those floods occured, but there were Indians here when the Columbia River broke through a land slide dam 500 years ago and arrived at Portland area with an estimated 100 foot deep surge of water which devistated the Troutdale and other nearby areas.
The ice dam holding back Missoula Lake was over 2000 feet tall.
Lake Missoula was as big as Lakes Erie and Ontario combined.
The flood force was equal to 60 Amazon Rivers flowing together.
It took about four days for the lake to drain after the dam broke.
During maximum glaciation, the ice was thick enough to pass over the highest peaks of the Selkirk and Cabinent Ranges at elevations of more than 6,000 feet. This required an ice sheet to be more than 4,500 feet thick in the vicinity of Sandpoint. The ice may have been more than 2,000 feet thick at the southern end of Lake Pend Oreille during maximum glaciation.
About Washington State:
Floods from glacial Lake Missoula passed through the northern part of Pend Oreille Lake. Ice dams forming glacial Lake Missoula failed many times causing floods to move across northern Idaho. These catastrophic floods flowed south and southwest scouring great channels in the Columbia Plateau in the eastern and central parts of the State of Washington. This area is commonly called the channeled scablands. Three terraces along the Clark Fork and Pend Oreille River valleys were formed by the three floods from glacial Lake Missoula.
Glacial Geology of the Southeastern Sawtooth Mountains
Fluvial Terraces on the Middle Fork Salmon River, Idaho.
Field Guide to Pleistocene Lakes Thatcher and Bonneville and the Bonneville Flood, Southeastern Idaho
The Lake Bonneville Flood
The Idaho Overview modules were created by Digital Atlas staff members Jacqueline Harvey, Vita Taube and Diana Boyack.
An alternate record written in metrics about The Spokane Flood:
At the ice dam across Clark Fork River, the lake reached a depth of 610 meters and covered 7,770 square kilometers of western Montana, and contained more than 2,084 cubic kilometers of water.
As the climate warmed, the weakening base of the ice dam ruptured and the greatest flood in recorded geological history began.
Water rushed through the breach westward to Lake Pend d Oreille at 40 cubic kilometers per hour, overflowed the lake then surged westward to Spokane, Washington.
Striking a plateau in eastern Washington, the flood spread out carving out the Channeled Scabland. A feature it created there is the Grand Coulee canyon, an 80-kilometer long trench up to 10 kilometers wide with steep walls of basalt 274 meters high.
The flood also carved out Dry Falls, 5.6 kilometers wide with a drop of more than 122 meters. At its height, the flood was 244 meters high. It formed the Camas Prairie's rolling hills, each up to 11 meters high and spaced 152 meters apart, covering an area of 16 square kilometers. The water rushed on across the Camas Prairie at an estimated rate of 85 kilometers per hour.
From there the flood turned south and surged down the Columbia River. When it reached the narrow Wallula Gap, being constricted, it backed up and formed a large lake, while it surged through the gap at a rate of 167 cubic kilometers per day.
At Portland Oregon area it flowed up the Willamet River a hundred and forty kilometers and drowned the Tualatin Valley and both sides of the I5 corridor, wherein it flowed back down the river to the Columbia and surged onward to the sea.
When the torrent reached the Pacific Ocean, it had traveled 966 kilometers and left its mark across 41,440 square kilometers of land.
As incredible as this seems, a scientist who first theorized this flood, J Harlen Bretz, believed it occurred many times as the glacier kept reforming the ice dam after each breakthrough by lake waters.