The Pleistocene Glacial History of the Lake Wellman Area, Darwin Mountains, Antarctica.

• Main Author: Hood, David John
• Format: Other/Unknown Material
• Language: English
• Published: University of Canterbury. Geological Sciences 2009
• Subjects: Antarctic; Darwin Mountains; East Antarctic Ice Sheet; Freed; Hatherton Glacier; Polar Plateau; Ross Sea; Transantarctic Mountains; Wellman; Antarc*; Antarctica; Ice Sheet
• Online Access: http://hdl.handle.net/10092/3939; https://doi.org/10.26021/7447

The Darwin and Hatherton Glaciers form a major system that drains a significant portion of the East Antarctic Ice Sheet (EAIS) through the Transantarctic Mountains (TAM) into the Ross Sea. Flow lines along their length demonstrate that they connect back to Dome Cirque on the Polar Plateau. Very little is known about the way these outlet glaciers have drained the EAIS in the past. However, information on their previous behaviour in response to global climate change and EAIS activity is recorded in their geomorphology. An ice-free region adjacent to Lake Wellman contains a well preserved sequence of moraines that provides evidence of glacial ice fluctuation related to earlier climates. Consequently, this area has potential as an appropriate site for investigating past glacial movement and change. A study was therefore conducted in the Lake Wellman area in order to examine the drift material left behind as the Hatherton Glacier retreated. This was done to obtain information that would help explain the manner and timing of glacial recession. A geomorphology map was constructed using data obtained from a series of transects placed across the drift moraine material. The transects were located at different elevations ranging between 800 m and 1200 m a.s.l., and were at distances between 4 and 8 km from the present glacier edge near Lake Wellman. Field data were collected from clast material sampled at regular intervals along each transect. These records consisted of assessments and measurements of clast lithology type, average size, hardness measured with a Schmidt hammer, angularity or roundness, and degree of weathering. The field data demonstrated that for clasts of dolerite and sandstone, angularity decreased and roundness increased significantly with altitude. No such trend occurred with clasts of gabbro, granite or basalt. The field observations therefore indicated that clasts at higher elevations and greater distances from the present glacial ice had been freed from the receding ice earlier and hence exposed for ...