Background
The Bonneville Landslide was a massive ground movement that occurred around 1200 AD. It was so big that it briefly blocked the Columbia River. The river’s water volume pushed through the blockage, but the uneroded portions of the landslide created a four-mile stretch of rapids in the river that are known as the Cascades of the Columbia.
The Oregon Territory was established in 1848. It encompassed all of the current states of Idaho, Oregon and Washington, as well as parts of Wyoming...