Black and white photograph of upper salmon pool at Gravel Lake [likely Lac des Gravier].

Black and white photograph of falls at the Mill River (Rivière du Moulin) in Québec.

Black and white photograph of Lower Falls, Yellowstone National Park. Taken by Robert Merrill, looking down from brink.

Black and white photograph in portrait orientation of the Lower Falls from Red Rock, Yellowstone National Park.

Black and white photograph in portrait orientation of the Grand Canyon of the Yellowstone River, Yellowstone National Park. Taken by Robert Merrill, looking east below Grand View.

Black and white photograph in portrait orientation of the Grand Canyon of the Yellowstone River, Yellowstone National Park. Taken by Robert Merrill, looking south from Inspiration Point.

Black and white photograph in portrait orientation of the Grand Canyon of the Yellowstone River, Yellowstone National Park. Taken by Robert Merrill looking north.

Black and white photograph of the Grand Canyon of the Yellowstone River. Taken by Robert Merrill from Grand View.

Black and white photograph looking northwest along Abbot's Brook in Trenton, New Jersey, near Argillite site.

Colorado River North of Shoshone power plant.

Colorado River below Shoshone.

Colorado River near Sulphur Springs.