One claim I've seen is that after 10,000 years, the Hoover dam will barely be recognizeable, and all the rest will be gone ... reduced to elements again. Excep

One claim I've seen is that after 10,000 years, the Hoover dam will barely be recognizeable, and all the rest will be gone ... reduced to elements again. Except for the rock piles. 100 million years, not so likely.