Bone Mountain (Oregon)

Southern Oregon Coast Range
Cow Creek, a tributary of the South Umpqua River
Highest point
Peak	Bone Mountain
Elevation	3,540 ft (1,080 m)
Coordinates	42°54′58″N 123°51′00″W / 42.91611°N 123.85000°W / 42.91611; -123.85000Coordinates: 42°54′58″N 123°51′00″W / 42.91611°N 123.85000°W / 42.91611; -123.85000
Dimensions
Length	55 mi (89 km) North-South
Geography
Southern Oregon Coast Range
Country	United States
State	Oregon
Parent range	Oregon Coast Range, Pacific Coast Ranges
Borders on	Central Oregon Coast Range and Klamath Mountains
Geology
Age of rock	Paleocene and Eocene
Type of rock	volcanic and forearc basin

The Southern Oregon Coast Range is the southernmost section of the Oregon Coast Range, in the Pacific Coast Ranges, located in the southwest portion of the state of Oregon, United States, roughly between the Umpqua River and the middle fork of the Coquille River, beyond which are the Klamath Mountains. To the east is the Umpqua Valley and to the west the Pacific Ocean. This approximately 55-mile (89 km)-long mountain range contains mountains as high as 3,547 feet (1,081 m) for Bone Mountain. The mountains are known locally in the Roseburg area as the Callahan Mountains, or simply as The Callahans.

As with the Oregon Coast Range as a whole, the Southern Oregon Coast Range likely began as an ocean island chain that collided with the continental tectonic plate of North America more than 60 million years ago. In the Southern Range the 64‑million-year-old Roseburg volcanics that formed this section are the oldest portions of the entire range. The range is part of a forearc basin that has slowly rotated about 51 degrees since the Eocene period. Much of the mountain structures are pillow basalt formations created during the volcanic period and then uplifted with the collision into the continental plate. Other geologic features are mainly the result of erosion and weather forces carving steam beds and valleys out of the rock formations.

The Oregon Coast Range is home to over 50 mammals, 100 species of birds, and nearly 30 reptiles or amphibians that spent a significant portion of their life cycle in the mountains. Birds living in the Southern Coast Range include a variety of smaller and larger bird species. These include northern goshawks, peregrine falcons, pileated woodpeckers, olive-sided flycatcher, and western bluebirds. The northern spotted owl, listed as a threatened species by the United States also inhabit the mountain forests. Aquatic life includes river lamprey, Pacific lamprey, coastal cutthroat trout, Millicoma longnose dace, Umpqua chub, red-legged frogs, southern seep salamander, western pond turtles, coho salmon, Chinook salmon, steelhead trout, and others. Other wildlife includes fringed myotis bats, long-legged myotis bats, Townsend’s big-eared bat, fishers, and sharptail snakes, northern flying squirrels, red tree voles, Roosevelt elk, among others. Other small animals include shrews, moles, deer mice, and ermine.