Blue Hills (Washington)
| Blue Hills | |
|---|---|
 Blue Hills
Location of the Blue Hills
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| Highest point | |
| Peak | Gold Mountain |
| Elevation | 1,761 ft (537 m) |
| Coordinates | 47°32′55″N 122°47′10″W / 47.54861°N 122.78611°W |
| Geography | |
| Country | United States |
| State | Washington |
| Region | Western Washington |
| Range coordinates | 47°33′00″N 122°48′00″W / 47.55000°N 122.80000°WCoordinates: 47°33′00″N 122°48′00″W / 47.55000°N 122.80000°W |
The Blue Hills just west of Bremerton, Washington, also called the Bremerton Hills, Bald Hills, and Wildcat Hills, consist of Gold Mountain, Green Mountain, and several informally named hills. Reaching an elevation of 1761 feet (537 meters), a thousand feet above the glacial till that fills the Puget Lowland, they form a prominent landmark visible around the region. They are formed of uplifted blocks of marine basalts, the steep-walled canyons between the various summits being the fissures between the blocks (particularly prominent at Gold Creek and Union River). In addition to Gold Mountain and Green Mountain (the named members of the Blue Hills) are several other prominent peaks unofficially named according to their elevation (in feet):
(For a fuller list of hills see List of mountains and hills of Kitsap County, Washington.) The name "Blue Hills" is said to come from the green trees appearing blue at a distance due to atmospheric optics.
The Blue Hills are perched on the north edge of the Seattle uplift, an east-west trending syncline or arch between the Seattle Fault and Tacoma fault formed by north-south compression of the bedrock. (See Puget Sound faults#Geological setting.)
Gold Mountain (on the south) is composed mainly of marine basalt flows and related volcaniclastic rocks (such as breccias and sedimentary interbeds) of the Crescent Formation, part of the Siletzia terrane that formed around 50 million years ago (early Eocene). Green Mountain is formed of slightly older formations of gabbro and pegmatite, intruded by dikes of basalt and diabase. Most of the dikes are oriented north-northeast (NNE), suggesting they formed at a time of east-southeast–west-northwest (ESE-WNW) extension. This is parallel to the Olympic-Wallowa Lineament (OWL), a major regional feature that passes just north of Bremerton which some believe shows strike-slip (horizontal) motion, but a connection with the OWL is yet to be shown. Sharp downwarping of these formations has created numerous faults, including the dip-slip (vertical movement) Gold Creek fault that separates the two mountains. Strands of the Seattle fault, which east of here trend nearly due west-east, appear to turn to the southwest in the vicinity of Green Mountain.
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Wikipedia