This otherworldly landscape was a lot of fun to explore. I did a little research and learned that these unusual red sandstone rocks, called concretions, were formed in an ancient sea bed when materials like calcite and iron oxide formed a sphere around a nucleus such as a bones or shells, and "grew" as water swirled around depositing more. These spheres were then buried in softer material and when the soft bedrock washed away it left these alien-looking boulders. One of the most striking things about these orbs is the sheer size of them - some over 2.5m (8 feet) in diameter.
In the top picture you can faintly see on the horizon the peaks of Gold Butte and West Butte in northern Montana.
It was a chilly spring day when we were there so we didn't see any snakes, but in warmer times of the year you have to watch where you step, as rattlesnakes are common here. There is also bull snakes, short-horned lizards, and even scorpions. We saw lots pronghorns and mule deer in the area, and were lucky enough to have a Short-Eared Owl pose for us as we were leaving.(Previously posted here).