Both caves are carved from Navajo sandstone and have been excavated by archeologists. They found many interesting artifacts that are thousands of years old.
The above photo is from the University of Utah's Anthropological Papers Number 104, 1980, titled "Cowboy Cave" by Jesse D. Jennings. The photo from the book shows examples of sandals and woven objects the archeology team discovered.One 8000 year old sandal was found. The dung of mammoth, bison, an extinct type of horse, camel and sloth was recovered from these caves. Ornaments, leather pouches, unfired clay figurines, split-twig figurines,
Surprisingly, we found a group of about 10 college aged kids from Missoula camped near the cave. Way out in the middle of nowhere, you don't expect to see anyone, but hikers tend to be friendly folk. We stopped and visited for a few minutes before moving on.