Ripples appear as ridges 15 to 50 feet high, 100 to 250 feet wide, and from 300 feet to a half-mile long. While the form, structure and arrangement of these features are similar to that of ordinary current ripple marks, they are termed giant flood ripples, due to their large size. The giant flood ripples at this site are unusual due to their being on the down-current side of notches in a ridge separating two basins that were both subsidiary to the main course of Lake Missoula in the Clark Fork Valley. The best examples of giant flood ripples are found in Camas Prairie.