Landscape evolution of Antarctica

The relative roles of fluvial versus glacial processes in shaping the landscape of Antarctica have been debated since the
expeditions of Robert Scott and Ernest Shackleton in the
early years of the 20th century. Here we build a synthesis of
Antarctic landscape evolution based on the geomorphology of
passive continental margins and former northern mid-latitude
Pleistocene ice sheets. What makes Antarctica so interesting
is that the terrestrial landscape retains elements of a record of
change that extends back to the Oligocene. Thus there is the
potential to link conditions on land with those in the oceans
and atmosphere as the world switched from a greenhouse
to a glacial world and the Antarctic ice sheet evolved to its
present state. In common with other continental fragments of
Gondwana there is a fluvial signature to the landscape in the
form of the coastal erosion surfaces and escarpments, incised
river valleys, and a continent-wide network of river basins.
A selective superimposed glacial signature reflects the presence or absence of ice at the pressure melting point. Earliest
continental-scale ice sheets formed around 34 Ma, growing
from local ice caps centered on mountain massifs, and featured phases of ice-sheet expansion and contraction. These
ice masses were most likely cold-based over uplands and
warm-based across lowlands and near their margins. For 20
million years ice sheets fluctuated on Croll-Milankovitch frequencies. At ~14 Ma the ice sheet expanded to its maximum
and deepened a preexisting radial array of troughs selectively
through the coastal mountains and eroded the continental
shelf before retreating to its present dimensions at ~13.5 Ma.
Subsequent changes in ice extent have been forced mainly by
sea-level change. Weathering rates of exposed bedrock have
been remarkably slow at high elevations around the margin of
East Antarctica under the hyperarid polar climate of the last
~13.5 Ma, offering potential for a long quantitative record
of ice-sheet evolution with techniques such as cosmogenic
isotope analysis