Ping. When did the huge fresh water lakes in North America collapse?Looks like neither Farmfriend or Rightwhale answered, but someone else may have. If so, I do apologize.
I got a good laugh out of this -- "The accepted model in geology was and is Uniformitarianism." But even worse was a letter some years ago to Science News in which the writer (a professor, which is kinda sad) dumped all over the Chicxulub impact (or possibly just the Alvarez model, in case it was longer ago than 1990), claiming that, other than this flood event, no catastrophic events have ever taken place on Earth.Channeled Scablands TheoryJ. Harlan Bretz... proposed a flood in which the sudden release of a volume of water much larger than that which now flows through the area produced the very large scale erosion. This would require the formation of a dam which would hold back the normal rainfall and snowmelt for many years, and then suddenly break, releasing this water over a period of days of weeks. Such a dam could be made by a glacier. If it blocked a stream valley, water would rise behind it. If it failed, it would do so catastrophically since as it began to break up, blocks of ice would float away, so the dam would fail from the bottom up. This would provide the large volumes of water needed to explain erosional features such as Dry Falls and explain why these features don't conform to the more common characteristics of stream erosion (V-shaped valleys, streams follow valleys). Since the flood(s) appeared to originate in the Spokane area, he termed them the Spokane floods.
Spokane Outdoors
I have an answer, looks like it was between 8,000-7,500BC.