Columbia subject headings:
Geology, Stratigraphic.
Geology--North America.
Paleontology--North America.
Paleontology.
Harvard subject headings:
Geology, Stratigraphic
Geology--North America
Paleontology
Paleontology--North America
Princeton subject headings:
Geology, Stratigraphic.
Geology--North America.
Paleontology--North America.
Paleontology.