Moaning Cavern

Moaning Caverns is a solutional cave located in Calaveras County, California, near Vallecito, California in the heart of the state's Gold Country. Moaning Cave is a vertical solution cavity and dome pit which developed along a fracture in metamorphosed limestone. It is part of the Calaveras Complex of the Sierra Nevada foothills. The largest room in the cave in over 37 metres (121 ft) tall. Today the cave serves as a tourist attraction in Northern California. It is open to the public for walking tours and spelunking. Including the off-trail areas, the cave reaches a depth of 410 feet (124 m). The portion of the cave developed for tourists consists of a spacious vertical shaft 165 feet tall, which is descended by a combination of stairs and a unique 100-foot-high (30 m) spiral staircase built in the early 1900s. The cave was first described on December 7, 1851 in the The Daily Alta California. A variety of artifacts were located in the cave, including human remains and detritus. It gets its name from the moaning sound that echoed out of the cave, however expansion of the opening to allow access for the public disrupted the sounds.

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).