Former glacial lakes of the Bunger Hills,Antarctica

The Bunger Hills in East Antarctica occupy a land area of approximately 400 km². They have been exposed by Holocene retreat of the Antarctic ice sheet and its outlet glaciers. The accompanying sea level rise flooded the marine inlets that now separate the northern islands and peninsulas from the major part of the hills. During deglaciation the continental ice sheet margin retreated south‐eastwards with several temporary halts, during which ice‐dammed lakes were formed in some valleys. These lakes were maintained long enough to permit formation of beaches of sand and gravel, and for the erosion of shore platforms and low cliffs in bedrock. Around the western end of Fish Tail Bay impressive shoreline features 20 m above sea level define a former ice‐dammed lake that was 5.5 km long. A similar 7 km long former ice‐dammed lake was formed at Lake Dolgoe. The more extensive and deeper glacial lake is revealed by well‐developed and preserved shoreline features cut at 29 m which is 16 m above present lake level. In addition, several small ice‐dammed lakes existed temporarily near Lake Shchel and in the valley to the west. Lake Fish Tail existed more than 6,900 ¹⁴C years ago and Lake Shchel probably more than 6,680 ¹⁴C years ago. It is inferred that the shore platforms and beaches were formed by lake ice and wave action over considerable periods when the lakes were impounded by steep cold ice margins. There appears to have been a balance between meltwater input and evaporative loss from the lakes in the cold dry continental climate. There is no evidence for rapid lake level fluctuations, and there was very little input of clastic sediment. This resulted in poor development of deltaic and rhythmically laminated lake floor deposits. It is suggested that such deposits are more characteristic of ice‐dammed lakes formed in association with wet‐based temperate ice than those associated with dry‐based polar ice.