Alpine-type valley and cirque glaciers in the northern Prince Charles Mountains
In addition to the larger ice sheet outlet glaciers found within the northern Prince Charles Mountains, such as the Scylla and Charybdis Glaciers, small-scale drainage systems of alpine-type valley glaciers or cirque glaciers also occur on many of the massifs. Although such small-scale drainage systems have already been extensively studied in the Transantarctic Mountains, where they flow into dry valleys or snow-free oases, they remain the subject of on-going research within the Prince Charles Mountains.
The alpine-type glaciers of the Prince Charles Mountains reveal information regarding the behaviour of the East Antarctic Ice Sheet and the world's largest drainage system, the Lambert Glacier. For example, the present day snowline altitudes are influenced by snow-bearing winds, particularly the summer winds that carry moisture inland from the open waters of Prydz Bay. The retreat of these glaciers during the Last Glacial Maximum was in contrast to the expansion of the larger ice-sheet outlet glaciers and is thought to have occurred in when sea-ice cover around the continent expanded, resulting in the reduction sea-water as a moisture source.
These alpine-type glaciers have formed through a leeward or snowfence effect on Loewe Massif, located within the northern Prince Charles Mountains approximately 240 km inland from the coast. These glaciers have redeposited drift (carried by the katabatic winds) which was deposited on the leeward or sheltered side of the massif at 600m above sea level. The snouts are located at approximately 220 to 250m above sea level and show evidence of minor indentation on the moraine sweep left behind from the Charybdis Glacier during the Last Glacial Maximum (LGM) approximately 20,000 years ago.
Just like seeing the tip of the iceberg, the northern Prince Charles Mountains are just showing their mountain tops above the glaciers (>1000m in thickness) that flow through the ranges. In the northern Prince Charles Mountains, the Nemesis, Charybdis and Scylla Glaciers, as well as the Lambert Glacier, flow past the mountains that support the smaller scale alpine-type glaciers that are typically 1 km wide and 10 km long.
The cirque is oriented to the southwest and assumed to be receiving accumulation from the drift laden katabatic winds. Distinct lateral and terminal moraines suggest that this glacier has retreated significantly from its maximum extent. The snout terminates ~500m above the surface of the outlet glacier, over-riding a Last Glacial Maximum/pre-Last Glacial Maximum surface that appears as polygon patterns (due to their ice core nature).
The location of the moraine, relative to the glacier, indicates both the maximum dynamics/behaviour of the glacier and the current dynamics. This glacier is retreating from its maximum extent/volume. The debris constituting the moraine till can be traced to both the cirque/headwall and the terrain that the alpine-type glacier flowed over.
Their cirques are oriented to the northeast to receive maritime precipitation. The elevation of the cirque base is 960m above sea level (right hand side) and 1160m above sea level (left hand side) and the snouts are at 80 and 60m above sea level, respectively. Lateral moraines are clearly visible with both alpine-type glaciers at, or near, their maximum extent. These glaciers are approximately 320 km from the open water and they are flowing towards the Lambert Glacier (in the foreground).
This has occurred on the northern face of Mount Jacklyn near the Australian National Antarctic Research Expeditions (ANARE) summer base of Dovers, Athos Range, northern Prince Charles Mountains. These moraines, like most others in the Prince Charles Mountains, are ice-covered, meaning that they are solid ice with a coating of rocks and dirt which prevents melting due to a lack of exposure.
A frozen melt lake is visible immediately in front of a lateral moraine from the Charybdis Glacier.
The ratio of the ice cliff to the apron (debris at the ice cliff base) indicates that this glacier is near equilibrium (not advancing or retreating, northern Prince Charles Mountains.
The rock and dirt acts as an insulation cover over the ice that hampers sublimation. The small channels in the ice surface occur as a result of the brief period in summer when ablation can occur due to melt, not sublimation (from solid to vapour), northern Prince Charles Mountains.
Krebs, K.A. and Mabin, M.C.G. (1997) Distribution, activity and characteristics of the alpine-type glaciers of the northern Prince Charles Mountains, East Antarctica. Antarctic Science
Krebs, K.A. (personal communication, 1997)
Mabin, M.C.G. (1992) Late Quarternary ice surface fluctuations of the Lambert Glacier. In: Yoshida, Y., Kaminuma, K. and Shiraishi, K. (editors) Recent Progress in Antarctic Earth Science, p. 683-687. Terra Scientific Publishing Company, Tokyo.