Page:Origin of the High Terrace Deposits of the Monongahela River.pdf/12

Rh route via Sharon instead of the Mahoning, and that the lower portion of the latter stream is of recent origin. The Slippery Rock was turned southward at Kennedy's upper mill by the advancing ice-sheet which filled its pre-glacial valley, and on retreating left a dam of drift 100 feet high across its former course, while the wild gorge and raging stream between Kennedy's mill and the Connoquenessing, so different from the wide valley and sluggish current above the mill, though the outcropping rocks are the same, fully attest the recent origin of the twenty-mile cut between the mill and the Connoquenessing, near Wirtemburg.