Oregon Caves National Monument is a National Monument in the northern Siskiyou Mountains of southwestern Oregon in the United States. The main part of the 488-acre (197 ha) park, including the marble cave and a visitor center, is located 20 miles (32 km) east of Cave Junction, on Oregon Route 46. A separate visitor center in Cave Junction occupies 4 acres (1.6 ha) of the total. Both parts of the monument, managed by the National Park Service, are in southwestern Josephine County, near the Oregon–California border. The climate is generally mild even at the cave's elevation of about 4,000 feet (1,200 m) above sea level, but icicles can form at the cave entrance, and winter snow sometimes blocks the park highway. Elijah Davidson, a resident of nearby Williams, discovered the cave in 1874. Over the next two decades, private investors failed in efforts to run successful tourist ventures at the publicly owned site. After passage of the Antiquities Act by the United States Congress, President William Howard Taft established Oregon Caves National Monument, to be managed by the United States Forest Service, in 1909. The popularity of the automobile, construction of paved highways, and promotion of tourism by boosters from Grants Pass led to large increases in cave visitation during the late 1920s and thereafter. Among the attractions at the remote monument is the Oregon Caves Chateau, a six-story hotel built in a rustic style in 1934. It is a National Historic Landmark and is part of the Oregon Caves Historic District within the monument. The Park Service, which assumed control of the monument in 1933, offers tours of the cave from mid-April through early November. Oregon Caves is a solutional cave, with passages totaling about 15,000 feet (4,600 m), that formed in marble. The parent rock was originally limestone that metamorphosed to marble during the geologic processes that created the Klamath Mountains, including the Siskiyous. Although the limestone formed about 190 million years ago, the cave itself is no older than a few million years. Valued as a tourist cave, the cavern also has scientific value; sections of the cave that are not on tour routes contain fossils of national importance. In addition to cave touring, activities at the park include hiking, photography, and wildlife viewing. One of the park trails leads through the forest to Big Tree, which at 13 feet (4.0 m) is the largest diameter Douglas-fir known in Oregon. Lodging and food are available at The Chateau and in Cave Junction. Camping is available at Forest Service campgrounds and private sites in the area.