Lehman Caves, Nevada
November 15, 2012
Lehman Caves is actually one cave system in Nevada’s Great Basin National Park. Among the interesting formations in the caves are the shield formations seen above. Lehman Caves contains over 300 of these relatively rare shield formations. It is not completely understood how they are formed, but typically, they are made up of two round and flat pancake-like shields with a very thin crack between them. They tend to form at angles from the floor and ceiling.
The cave was “discovered” by Absalom Lehman in 1885 (Native Americans had used the caves for burials prior to the arrival of Europeans). Lehman promoted the cave, and charged tourists to visit. In order to encourage visitors and make it easier to move around in the caves' cramped quarters he allowed them to take pieces, particularly stalactites, with them: “You break it, you take it.” Thus, many of the formations were broken off and removed.
Lehman Caves began formation during the early Cambrian period, approximately 600 million years ago. At that time, much of the area around the caves was an inland sea. Most of what we know of as Utah and Nevada was covered by this warm and shallow body of water. As sediment layers built up on the bottom of this sea, limestone was formed from the silt, sand and skeletal remains of sea life. The limestone was greatly compressed as a result of the pressure of the many layers of sediment.
As the eons passed, groundwater in the area absorbed carbon dioxide from the air and decaying vegetation in the soil, creating carbonic acid. This acidic water was able to trickle down through bedrock and dissolve the limestone. Cavities were formed, and as the sea level dropped, hollow “passageways” were left behind. Since then, the seeping water has continued to modify the caves, though at a much slower rate. A tour of the caves provides multiple opportunities to view water still actively a part of the cave system. During the tour, a Ranger may tell you that it’s believed that if water in the caves drips on you, it's good luck. This author has not noticed an increase in her luck because of being dripped on by multiple stalactites. Photo taken October 16, 2012.
Photo details: Top - Camera Maker: Canon; Camera Model: Canon PowerShot SD1300 IS; Focal Length: 5mm; Aperture: f/2.8; Exposure Time: 0.167 s (1/6); ISO equiv: 800; Exposure Bias: none; Metering Mode: Matrix; White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB; Software: Adobe Photoshop 7.0. Insert - Same except: Exposure Time: 0.017 s (1/60); ISO equiv: 400; Flash Fired: Yes (Auto, return light detected).