42 Glacial and Postglacial Environments on the Frontier: Quaternary Studies in the New England-Canadian Border Region (Posters)
Tuesday, 13 March 2007
1:00 PM - 4:45 PM
THE SHATTUCK MOUNTAIN CHANNELS AND POTHOLES: EVIDENCE FOR HIGH-VELOCITY SUBGLACIAL STREAMFLOW IN THE NORTHERN GREEN MOUNTAINS, VERMONT
Paper number: 42-4
Program: THEME SESSIONS
Time: 1:00 PM – 4:45 PM
Authors
Abstract
It is unlikely that this channel network developed as an outlet to Glacial Lake Winooski, the large glacial lake that occupied the Winooski and Lamoille river valleys when ice in the Champlain valley blocked the outlets to these valleys. While the drainage divide where the channel network is developed lies below the local elevation of Glacial Lake Winooski (~330 m asl), reconstruction of the Laurentide ice sheet in the Champlain valley indicates that during the entire history of Lake Winooski, the ice sheet at the latitude of the channels was thick enough to flow across the drainage divide. Furthermore, the local NW to SE hydraulic gradient within the ice sheet would have prevented lake water from draining across the divide to the northwest.
A more likely explanation that accounts for the channel system and potholes developed on both sides of the drainage divide is that the channels developed in a subglacial (confined) drainage system similar to that responsible for the Labyrinth in Antarctica. The large scale of the potholes suggests that very high velocity water moved through this system, possibly during a single catastrophic drainage event.