Niagara Falls Indians

I was looking at an old map that showed the location of an Indian tribe that lived near Niagara Falls.  The camp was set right on a hill next to the falls.  They could look down the hill right into the falls.  There was a gentle slope that lead to a cliff.  If an Indian fell asleep on the slope he might roll down the slope and fall off the cliff into the falls.  I was looking at the river downstream from the falls and there was a lot of wood and branches that were forming a dam.  Somebody told me the dam would eventually become permanent and fill up the river so there would be no falls anymore.