Columbia subject headings:
Geology--Hudson River Valley (N.Y. and N.J.)
Hudson River Valley (N.Y. and N.J.)--Description and travel.
Hudson River Valley (N.Y. and N.J.)--History.
Harvard subject headings:
Hudson River Valley (N.Y. and N.J.)--History.
Princeton subject headings:
Geology--Hudson Valley.
Hudson Valley--Description and travel.
Hudson Valley--History.