Telegraph: The most extensive survey ever taken of the Antarctic sea floor shows how the ice retreated during a warming in temperatures 10,000 years ago. The British Antarctic Survey (BAS) and the Alfred Wegener Institute in Germany used sonar technology on board ships to survey an area the size of Wales below the Amundsen Sea. The images show channels as wide as a motorway and three giant troughs, as wide as the English Channel. Rob Larter, from the BAS, said understanding the …