The rock that Lehman Caves formed in began as seafloor. Around 550 million years ago, in the Cambrian, this part of eastern Nevada lay under a relatively warm, shallow ocean, and the limestone and marble that the cave is dissolved out of was laid down there. The cave decorations throughout the system come from that same rock going back into solution and coming out again.
The cave got much of its present depth during the Pleistocene, when prolonged and increased water flow cut down through the fractured bedrock. Eventually the water level dropped away and left the rooms and cavities behind, dry and open.
It runs about two miles, which makes it the longest known cave in Nevada. The park offers two tours of it, a 0.6 mile route lasting around ninety minutes and a shorter 0.4 mile one.
President Warren G. Harding created Lehman Caves National Monument by proclamation on 24 January 1922. It stayed a separate monument for over sixty years, until Congressman Harry Reid's advocacy brought it into the new Great Basin National Park on 27 October 1986.
The park around it is worth the drive on its own. It protects 77,180 acres and holds groves of ancient bristlecone pines, the oldest known non-clonal living things on Earth, the Wheeler Peak Glacier below the 13,063 foot summit, and some of the darkest night skies in the contiguous United States.
Cave tours are guided, ticketed and frequently sold out, so book ahead. The park sits about 290 miles north of Las Vegas, and there is very little in between.
Other places on the map within a couple of hours.
