Mystery of the Mega-flood

For many years, geologists had no idea what caused the unique formations of the Channeled Scablands in Washington State. The Scablands have odd holes in the ground and a waterfall with no water. Originally, scientists believed that the Scablands were formed by gradual erosion over millions of years. The problem with that theory was that there was no river that went through the Scablands that could have made the formations.

Another popular theory was that glaciers coming down from Canada had carved out the landscape. However, those glaciers never reached the area that is now the Scablands. During the 1920s, geologists developed the theory that a major catastrophe shaped the Scablands overnight - a mega-flood. They believed that a glacier had formed a dam in the Glacial Lake Missoula, and that, when stressed, the ice formed cracks, and water under great pressure formed bubbled and forced its way into the cracks. The friction created by the flow of the water released heat that melted the glacier. This released 500 cubic miles of water, which shaped the landscape. More recently, scientists have speculated that more than one flood may have contributed to the formation of the Scablands. Ash in the sediment from Mt. St. Helens and the many layers of deposits in the canyons all suggest more than one flood.

Here is a link to more information about the Channeled Scablands.