Black and white lantern slide of a masonry arch bridge over a waterway in Old Panama.

Black and white lantern slide of a staircase in a ruined Cathedral tower in Old Panama.

Black and white lantern slide of Audie Merrill and another person stanidng on an overhead bridge in Rock City, Tennessee.

Black and white lantern slide of Audie Merrill, Flora (?) and Robert Merrill at Gnome's Overpass in Rock City, Tennesee.

Black and white lantern slide of Robert Merrill and Audie Merrill standing with Flora (?) in front of Mushroom Rock in Rock City, Tennessee.

Black and white lantern slide copy map of the Upper Geyser Basin of Yellowstone National Park from an unknown source.

Black and white lantern slide copy of the Yellowstone Park Map from a 1939 guidebook.

Black and white lantern slide of the Twin Lakes, Yellowstone National Park. Taken from the summit towards the northeast entrance.

Black and white lantern slide of the Yellowstone Lower Falls taken from the Uncle Tom Trail.

Black and white lantern slide of a natural bridge rock formation on an upper beach of Lake Yellowstone.

Black and white lantern slide of Robert Merrill standing next to the Lone Star Geyser Cone in Yellowstone National Park.

Black and white lantern slide of the Old Faithful geyser in eruption taken from Observation Point in Yellowstone National Park.

Black and white lantern slide of the Liberty Cap rock formation in Yellowstone National Park.

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 old lava flow formations near Soda Butte Creek.

Black and white lantern slide of Obsidian Cliff, Wyoming.

Black and white lantern slide of old lava flows on Purple Mountain in Colorado.

Black and white lantern slide of a lava cap south of Pocatello, Idaho, with a railroad and road in the mid and foreground.

Black and white lantern slide showing construction equipment and work on the Deer Creek Dam in Utah.

Black and white lantern slide of mountains at Dinosaur National Monument showing the jurassic era geologic folds.

Black and white lantern slide of a mountain in the Uinta Mountain range.