Sack Lunch Seminar (SLS)

SLS: Timothy Creyts -Lamont-Doherty Earth Observatory
Date Time Location
February 16th, 2011 12:10pm-1:00pm 54-915
Reflections on subglacial hydrology: a view from Antarctica


Beneath the Antarctic Ice Sheet, water networks act to lubricate the bed and enhance ice flow. Water leaves the network as it discharges to the ocean, or alternatively, freezes on to the underside of the ice sheet. Here, I discuss the mechanisms of subglacial water drainage with emphasis on freeze-on, mass redistribution, and effects on the subglacial topography. The recent AGAP aereogeophysical survey over Dome A, the highest point in central East Antarctica, is an unparalleled dataset and reveals the detailed structure of both the ice sheet and the underlying Gamburtsev Mountains. Water production is localized in deep valleys, and the ice sheet drives water away from Dome A through rugged alpine topography. Because ice sheet flow is not always codirectional with valley orientation, water often flows up steep bed topography and freezes. Along high, steep mountain ridges, freeze-on terminates water flow, produces discontinuities in subglacial networks, and accretes large volumes of basal ice. Frozen areas protect high peaks from further erosion and aid in their preservation. Observations of water drainage beneath West Antarctica illustrate the quasi-periodic nature of flow, and I use inferences and models to understand drainage mechanisms.