A lake emptied across a province
Near the end of the last ice age, glacial Lake Missoula burst repeatedly and sent floods across what is now eastern Washington, carving the Channeled Scablands.
Established2 min read
J Harlen Bretz looked at dry waterfalls, hanging valleys, and gravel bars the size of hills and argued for a catastrophic flood. The profession preferred uniformitarian explanations and resisted him for decades. Joseph Pardee then found the shorelines of a huge ice-dammed lake in Montana, and the source of the water was no longer missing.
The ice dam failed more than once. Peak flows are estimated in the millions of cubic metres per second. The floods crossed to the Pacific and left ripples on the seafloor.
Caveats
- There was not one flood. There was a series, over several thousand years.
- Discharge figures are reconstructions from the landscape, not gauge readings.
Sources
- 1Bretz J. H.. The Channeled Scablands of the Columbia Plateau. Journal of Geology 31, 1923.