Scientists Trace South Georgia’s Giant Ice History
South Georgia is an island of astonishing beauty – of imposing landscapes, and bewildering numbers of penguins, seals and seabirds.
(From BBC / By Jonathan Amos) — It also has some impressive ice fields, although none it seems quite like those of the past.
Some 20,000 years ago the island’s glaciers pushed out 50km and more from their current positions, reaching to the edge of the continental shelf.
The British Overseas Territory was in effect covered by a giant ice cap.
This realisation is reported in the current edition of the journal Nature Communications.
It is the result of investigations of the seafloor by a team of scientists from the UK, Germany and Australia.
“We were able to find a tracer of this ice cap – a ridge at the outer margin of the continental shelf that’s larger than all others, pretty much; and it’s fairly contiguous,” explained Dr Alastair Graham from Exeter University.
“You see it to the west, to the north, to the east, and even to the south where we don’t have much data. It’s quite a surprise because many scientists had assumed any ice cap was quite small.”
Dr Graham and his colleagues conducted sonar surveys around South Georgia using the British Antarctic Survey’s (BAS) research vessel, the James Clark Ross, and Germany’s RV, the Polarstern.
These ships mapped the long deep troughs cut by ancient glaciers. Evident in these channels are the countless, tell-tale markings of bulldozed sediments known as moraines.
But to fill out their picture, the researchers needed also to establish when these features were produced, and so they pulled up cores of seafloor material. Caught up in this mud and rock are the shelly remains of tiny animals that can be used to date the glacial deposits.
What emerges from all this study is a story of a rapidly changing ice-scape – one that has been incredibly sensitive to really quite small changes in temperature.
Read the full article here: http://www.bbc.com/news/science-environment-39303480