Cowanesque River flows eastward across Tioga County, in north central Pennsylvania, to join the Tioga at Lawrenceville. For 15 miles of its course, from Westfield to Nelson, the river meanders across flats three-quarters of a mile wide that broaden to 2 miles between Elkland and Osceola. Here, channel, banks, and valley sides are almost devoid of bedrock outcrops; but below and above the flats the stream flows through straighter, narrower valleys with plentiful rock outcrops. The flat is interpreted as the bed of a Pleistocene lake here named Glacial Lake Cowanesque.
The probability of lake occupancy of the Cowanesque valley was announced by Alden and Fuller,3 who concluded that such a lake originally formed in front of ice advancing from the northeast, which blocked and probably eventually filled the valley. A recurrence of lacustrine conditions accompanied ice withdrawal. Since the terminal moraine lies to the south and west, the . . .