Laurentide glaciation

19th century estimate of the boundaries of the Laurentide glaciation. Note: Alaska (and Siberia) were not covered by ice as prevailing wind patterns did not bring in moisture laden air, so almost no snow fell there, and thus these areas were glacier free.

The Laurentide glaciation is the most recent continent-spanning glacier in North America. It covered most of the northern half of North America for approximately 100,000 years, and started to recede 12 to 15 thousand years ago.

The most southerly extent of the glacier was in Ohio.

Three earlier glaciers had spanned much of North America over the last half million years.