Russian Journal of Earth Sciences
Vol. 5, No. 3, June 2003
The Arctic Center of Quaternary ice and flood
spreading:
A deductive model
M. G. Grosswald
Abstract
Early in the XIX century, the founders of glacial theory conceived of a "polar ice
cap'' centered on the North Pole and extending as far south as central Europe. However
later this
model was discarded. The deep Arctic Ocean, discovered in 1890s, was thought inconsistent
with the model. Moreover, a belief took hold that the Arctic was not more severely
glacierized
than now, as polar snowfall seemed insufficient to nourish much bigger ice masses.
So the
reigning concept of the XX century suggested that the past great ice sheets of Northern
Hemisphere
had mostly located on the mid-latitude continents.
This concept was first challenged in 1970s, when
Hughes et al. [1977]
put forth the model of an Arctic Ice Sheet (AIS) that had formed largely
in the Arctic Ocean. A core ice-shelf mechanism of Arctic Ice Sheet formation
was proposed, which suggested: first, an inception of
ice shelves in confined cold-water seas; second, turning the ice shelves into marine
ice domes
grounded on the polar continental shelves; and third, amalgamation of the Arctic
terrestrial,
marine-based, and floating ice components into a single Antarctic-style dynamic system.
Now, a
marine ice transgression hypothesis is proposed which suggests that the Arctic marine
ice domes
and thick floating ice shelf would push outwards and transgress onto adjacent lands.
The Arctic Ice Sheet was an unstable, threshold-like system, prone to generate nonlinear
responses to gradual change in forcing. The responses materialized in glacial surges,
Heinrich
events, and megafloods. As a result of the Earth's rotation, the system developed
a west-to-east
asymmetry.