Black and white photograph of Lena Billington Merrill standing below Point Lookout, Yellowstone National Park.

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 of Mud Volcano, Yellowstone National Park.

Black and white photograph showing a close view of a black bear cub, facing away from the camera. Taken by Robert Merrill at the Lake Colonial Hotel, Yellowstone National Park.

Black and white photograph showing a close view of a black bear cub, facing the camera. Taken by Robert Merrill at the Lake Colonial Hotel, Yellowstone National Park.

Black and white photograph of Lena Billington Merrill holding multiple fish on a line. Taken by Robert Merrill at the Lake Colonial Hotel, Yellowstone National Park.

Black and white photograph of the West Thumb Paint Pots by Yellowstone Lake, Yellowstone National Park. Two women can be seen standing in the distance.

Black and white photograph of Kepler Cascades, Yellowstone National Park.

Black and white photograph of bears at the back of the Old Faithful Inn, Yellowstone National Park.

Black and white photograph of the Daisy Geyser in eruption, Yellowstone National Park. A man is seen walking next to the geyser.

Black and white photograph of Punch Bowl Spring, Yellowstone National Park.

Black and white photograph of the Riverside Geyser in eruption, Yellowstone National Park. Taken by Robert Merrill looking southeast.

Black and white photograph of the Riverside Geyser in eruption, Yellowstone National Park. A group of people are standing and watching the geyser erupt. Taken by Robert Merrill looking east.

Black and white photograph of the Grotto Geyser at rest, Yellowstone National Park.

Black and white photograph of the Beehive Geyser, Yellowstone National Park, with Lena Billington Merrill facing the camera.

Black and white photograph of the Beehive Geyser in eruption, Yellowstone National Park. Lena Billington Merrill can be seen at a short distance from the geyser.

Black and white photograph of the Beehive Geyser before eruption, Yellowstone National Park. A man and a woman are standing near the geyser.

Black and white photograph of the Old Faithful geyser in eruption, Yellowstone National Park.

Black and white photograph of two bears by the Fountain Hotel, Yellowstone National Park.

Black and white photograph of a bear by the Fountain Hotel, Yellowstone National Park.The ground around the bear appears to be scattered with discarded metal cans.