<P> The Australian mainland, New Guinea, Tasmania and many smaller islands comprised a single land mass . This continent is now referred to sometimes as Sahul . </P> <P> Between Sahul and Sundaland--a peninsula of South East Asia that comprised present - day Malaysia and western and northern Indonesia--there remained an archipelago of islands known as Wallacea . The water gaps between these islands, Sahul and Sundaland were considerably narrower and fewer in number . </P> <P> In North America, the ice covered essentially all of Canada and extended roughly to the Missouri and Ohio Rivers, and eastward to Manhattan . In addition to the large Cordilleran Ice Sheet in Canada and Montana, alpine glaciers advanced and (in some locations) ice caps covered much of the Rocky Mountains further south . Latitudinal gradients were so sharp that permafrost did not reach far south of the ice sheets except at high elevations . Glaciers forced the early human populations who had originally migrated from northeast Siberia into refugia, reshaping their genetic variation by mutation and drift . This phenomenon established the older haplogroups found among Native Americans, and later migrations are responsible for northern North American haplogroups . </P> <P> On the Island of Hawaii, geologists have long recognized deposits formed by glaciers on Mauna Kea during recent ice ages . The latest work indicates that deposits of three glacial episodes since 150,000 to 200,000 years ago are preserved on the volcano . Glacial moraines on the volcano formed about 70,000 years ago and from about 40,000 to 13,000 years ago . If glacial deposits were formed on Mauna Loa, they have long since been buried by younger lava flows . </P>

At its maximum extent continental glacial ice in north america extended as far south as