Trilobites were scavengers in their time. In a sense, the giant beaver is already commemorated on Minnesota's state seal, which depicts the Falls of St. Anthony. This major waterfall on the Mississippi River is located in Minneapolis. It was this waterfall that buried one of the most famous giant beaver fossils 10,000 years ago. But it happened more than six miles from the waterfall s present location.
Rivers erode the rocks they flow over.
A plunging waterfall is an even more efficient agent of erosion. As the rock under the waterfall is eaten away, the waterfall migrates upstream. The Falls of St. Anthony migrated, on average, about one mile every 1,500-1,600 years.