Southern Oregon Coast Range

Southern Oregon Coast Range
West Fork Bridge over Cow Creek (Oregon).jpg
Cow Creek, a tributary of the South Umpqua River
Highest point
PeakBone Mountain
Elevation3,540 ft (1,080 m)
Coordinates42°54′58″N 123°51′00″W / 42°54′58″N 123°51′00″W / 42.91611; -123.85000
Dimensions
Length55 mi (89 km) North-South
Geography
Southern Oregon Coast Range is located in Oregon
Southern Oregon Coast Range
Southern Oregon Coast Range
CountryUnited States
StateOregon
Parent rangeOregon Coast Range, Pacific Coast Ranges
Borders onCentral Oregon Coast Range and Klamath Mountains
Geology
Age of rockPaleocene and Eocene
Type of rockvolcanic 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.[1]

Geology

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.[2] In the Southern Range the 64‑million-year-old Roseburg volcanics that formed this section are the oldest portions of the entire range.[2] The range is part of a forearc basin that has slowly rotated about 51 degrees since the Eocene period.[2] Much of the mountain structures are pillow basalt formations created during the volcanic period and then uplifted with the collision into the continental plate.[2] Other geologic features are mainly the result of erosion and weather forces carving steam beds and valleys out of the rock formations.[2]

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