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