Large examples of lava dams from the geologic record include those repeatedly developed from the western side of the Grand Canyon, with the largest remnant now termed Prospect Dam,[1] and in several locations within the Snake River drainage. The former 'Lake Idaho', which existed for more than 6.5 million years, filled the western portion of the behind such a structure and created the western section of the Snake River Plain, and accumulated 4,000 ft (1,200 m) of lake sediments.[2] Other locations include near American Falls, Idaho, and numerous others. Many of these were overtopped, washed out, or skirted by the outburst flood originating from ancestral Lake Bonneville.[3]