Black and white lantern slide of clay varves, or laminated sediment, along the Gibbon River in Wyoming.

Black and white lantern slide close-up view of petrified trees in the grass with measuring sticks.

Black and white lantern slide of Audie Merrill posing on a hillside next to a fenced-in petrified tree. Two other people, Sinclair and Virginia, are visible through the fence.

Black and white lantern slide of old lava formations on Amethyst Mountain in Wyoming.

Black and white lantern slide of Obsidian Cliff, Wyoming.

Black and white photograph of a stone pillar. The image is somewhat blurry.

Black and white photograph of a mountain partially covered with trees.

Black and white photograph of a mountain partially covered with trees.

Black and white photograph of a road next to a mountainside with a mountain range visible in the distance.

Black and white photograph of Gibbon Falls in Yellowstone National Park. Gibbon Falls is surrounded by mountains and forest.

Black and white photograph of the Fountain Geyser at Yellowstone National Park. Steam is rising from the geyser, and a pine tree stands between the geyser and the photographer.

Black and white close-up photograph of Punch Bowl Spring in Yellowstone National Park.

Black and white photograph of the active Jewel Geyser in front of a forest at Yellowstone National Park.

Black and white photograph of Hymen Terrace, Yellowstone National Park. Two women can be seen standing in the foreground of the image.

Black and white photograph of a horse-drawn coach at the Mammoth Hotel, Yellowstone National Park. Several people can be seen in and around the coach. Lettering on the side of the coach reads Yellowstone Park Transportation Co. Water damage is…

Black and white photograph of Jupiter Terrace, Yellowstone National Park. Taken by Robert Merrill from above. Water damage is visible on the image, which was scanned from the negative.

Black and white photograph of a horse-drawn coach in the Hoodoos, Yellowstone National Park. Five people are visible sitting on the coach.

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

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 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 Lower Falls, Yellowstone National Park. Taken by Robert Merrill, looking down from brink.

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.