The Tualatin Mountains (also known as the West Hills or Southwest Hills of Portland) are a range on the western border of Multnomah County, Oregon, United States. A spur of the Northern Oregon Coast Range, they separate the Tualatin Basin of Washington County, Oregon, from the Portland Basin of western Multnomah County and Clark County, Washington. The highest peak in the range is Dixie Mountain at . Other notable peaks include Cornell Mountain at 1,270 feet (390m), Council Crest at , and Pittock Hill, location of the Pittock Mansion. Despite steep slopes, periodic landslides, and multiple earthquake faults, many residences have been built in the Tualatin Mountains, though much of the northern portion is undeveloped land within the

Forest Park A forest park is a park whose main theme is its forest of trees. Forest parks are found both in the mountains and in the urban environment. Examples Chile * Forest Park, Santiago China *Gongqing Forest Park, Shanghai * Mufushan National Fores ...

. The landscape, inside and outside the park, is predominantly forested.

History

The hills date from the late

Cenozoic The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...

era, and range up to over . Composed mainly of basalt, the mountains were formed by several flows of the

Grande Ronde basalt The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt grou ...

flows that were part of the larger Columbia River basalts.Bishop, Ellen Morris. ''In Search of Ancient Oregon: A Geological and Natural History''. Timber Press, 2003. Human settlement goes back 10,000 years to the area's earliest known residents, the Chinook people. U.S. Route 26 (the Sunset Highway) is the principal transportation link through the hills, traveling through the

Vista Ridge Tunnels The Vista Ridge Tunnels are highway tunnels through the Tualatin Mountains ("West Hills") of Portland, Oregon, United States. Located in the Goose Hollow neighborhood, the tunnels pass through a hillside locally known as Vista Ridge which i ...

, Tanner Creek Canyon, and over the crest of Sylvan Hill. This route through the hills connecting the agricultural Tualatin Basin to the navigable Willamette River was developed as a

plank road A plank road is a road composed of wooden planks or puncheon logs. Plank roads were commonly found in the Canadian province of Ontario as well as the Northeast and Midwest of the United States in the first half of the 19th century. They were oft ...

in the 19th century. The Great Plank Road (Canyon/Jefferson Road) was a major factor in the early growth of the city of Portland. Since 1998, the

west side West Side or Westside may refer to: Places Canada * West Side, a neighbourhood of Windsor, Ontario * West Side, a neighbourhood of Vancouver, British Columbia United Kingdom * West Side, Lewis, Outer Hebrides, Scotland * Westside, Birmingham E ...

MAX Light Rail has run roughly parallel to US 26 through the hills, including a section tunneled deep underground.

Radio broadcasters

The Tualatin Mountains are home to the transmitter for iHeartMedia's KLTH.

History

Radio broadcasters

See also

References

Further reading