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AUBURN, Calif. (KTXL) — For those who have ventured along the Quarry Trail in the Auburn State Recreation Area and found the remnants of a large mining operation, they might think why is there a mine here and what is that big cave about?

To begin the cave is named Hawver Cave and it is located in El Dorado County.

El Dorado County is the origin place of California’s Gold Rush. In 1848 James Marshall discovered gold along the South Fork of the American River near Coloma, about 16 miles southeast of the cave’s location.

However, this large hole in the side of a California hill was not made for gold mining, but for limestone mining.

As early as the 1850s limestone was being mined out of the Hawver Cave on a smaller scale than in later years when the land was purchased by the Mountain Quarries mining company to mine the limestone for cement production and beet sugar production, according to the Gold Discovery Park Association.

Before mining operations began in full however though, John C Hawver, the man from which the cave gets its name, explored the natural cave in 1906, according to the Gold Discovery Park Association.

Hawver was an amateur geologist and paleontologist and when he discovered human bones in the cave he brought his findings to the University of California, which then began its own exploration in 1907 , according to the Gold Discovery Park Association.

Between the two explorations, the bones of a mastodon, mountain lion, bison and other fossils were found and were dated to be at least 5.3 million years old, according to the Gold Discovery Park Association.

Some of those fossils can still be found at the Sierra College Natural History Museum in Rocklin.

In 1912, Mountain Quarries began full operations of the mine, employing 150 to 240 men for two eight-hour shifts a day , according to the Gold Discovery Park Association.

During its operation the mine was the largest limestone quarry in Northern California and had electric power supplied by Pacific Gas and Electric.

During this level of operation 1,000 to 1,500 tons of limestone were produced per day and loaded onto a train.

The railroad tracks for the train that serviced the mine and the crushing plants were salvaged in 1942 to aide the war effort during WWII , according to the Placer County Historical Society

In 1953, mining was continued until 1976 and by the end of the mines operation about 9.1 million tons of limestone was collected.

Above the location of the cave is the former Spreakles Quarry which was also a limestone mine until it was turned over to the Bureau of Reclamation from Teichert Inc. and taken on by the Auburn SRA in 2001 , according to the Gold Discovery Park Association. That area is now known as Cave Valley Climbing Area.

Today the cave is operated by the Auburn SRA Canyon Keepers who are working to create a guided tour through the cave for the public.