Columbia subject headings:
Glacial epoch--North America--Maps.
Glacial landforms--North America--Maps.
Glaciers--North America--Maps.
Maps.
Harvard subject headings:
Geology, Structural--North America--Maps.
Glacial landforms--North America--Maps.
North America--Maps
Princeton subject headings:
Geology, Structural.
Glaciology.
Maps.
North America--Maps.