Hi everyone, you might enjoy this 11-minute, mapping-oriented video

https://www.youtube.com/watch?v=_uelSDhEKLo

Sincerely, Harvey

Harvey Thorleifson Ph.D., P.Geo., D.Sc., Director, Minnesota Geological Survey; State Geologist of Minnesota; Professor, Department of Earth Sciences; College of Science and Engineering; University of Minnesota; 2609 West Territorial Road, St Paul MN 55114-1009 USA; Telephone 612-626-2150; [log in to unmask]