I found this interesting image of the North American Ice Sheets during the last (Wisconsin) glaciation, c 20,000 years ago. The quality of the image is not very good, but you get the general idea.....
Note that there were four ice sheets, all joined together. (In Antarctica today we see the West Antarctic and East Antarctic Ice Sheets connected in a similar way.) Note that this was a very extensive glaciation in which the ice edge in many areas progressed beyond the limits of earlier glaciations. The exception is the area to the SW of the Great Lakes, where earlier glacial deposits are still exposed at the surface.
More detail here:
Map credit:
Dr. Judson L. Ahern
University of Oklahoma
The Last Global Maximum figure in the 2015 post entitled North American Ice Sheets is colorful and want to use it for my lectures to high school students. Do you have a source? Is it a small file that loses focus when enlarged? It does when I copy it as a jpg file.
ReplyDeleteHi Bob -- here is the original:
ReplyDeletehttps://www.behance.net/gallery/4803645/Geologic-Maps-and-Diagrams-for-College-Textbook
The artist does not claim copyright, so it's free to use for educational purposes.
Cheers
brian