About Formation Cave
At some prehistoric time a hot spring bubbled in Formation Cave, and filled pools above it. Like unto the hot springs at Yellowstone National Park, crusty edges formed around the pools, deposited by particles of rock which had dissolved into the water. Underneath these crusty pool rims, caverns were left.
Geologic changes caused the pools to dry up long ago, and now the crusty rims protrude from a carpet of grass and scattering of sagebrush. The cave is empty of water and open to exploration. A main cavern extends to the left and right just inside the entrance, and small side openings intersect it in several spots. The largest chamber in the cave (that we found) is just inside the entrance, and is tall enough to stand in, and about as wide, and about twenty-five feet long.
Formation Cave is just north of Soda Springs, Idaho on Trail Canyon Road. The cave, the nearby spring and the surrounding area are preserved by the Bureau of Land Management as a small park.