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

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 Riverside Geyser in eruption, Yellowstone National Park. Taken by Robert Merrill looking southeast.

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

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

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

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 east below Grand View.

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

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

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

Black and white photograph of the Norris Geyser Basin, Yellowstone National Park. Taken by Robert Merrill, looking northeast. A man can be seen standing at the left of the image, and a horse-drawn carriage appears to be driving up the road from the…

Black and white photograph of the Norris Geyser Basin, Yellowstone National Park. Taken by Robert Merrill, looking north. Several figures can be seen at a long distance. Water damage is visible on the image, which was scanned from the negative.

Black and white photograph of a group of people on Norris porch. Robert Merrill and Lena Billington Merrill are both visible in the image in addition to five other individuals. Photographer unknown. Water damage is visible on the image, which was…

Black and white photograph of a woman named Rebecca looking at a chipmunk, Yellowstone National Park. Water damage is visible on the image, which was scanned from the negative.

Black and white photograph of Obsidian Cliff, Yellowstone National Park. Water damage is visible on the image, which was scanned from the negative.