During the last million years, glaciers as high as cumulus clouds crossed this land at least four different times, and each time the river changed course through a transformed landscape of ice-scoured rock and piles of sand and gravel that blocked entire valleys. The result is a river that flows through valleys of many different ages. The far distant valley between Portageville and Nunda was carved by the Genesee River before the beginning of the ice age. The middle distant valley, where Lee's Landing is located, was initially formed before the last glacial period and was later recaptured by the present river. The 10,000-year-old canyon below is one of the river's most recent detours, and it proved too rugged and remote for early logging operations.