Jump to content

Oregon Coast Range

Coordinates:44°30′16″N123°33′10″W/ 44.50444°N 123.55278°W/44.50444; -123.55278
From Wikipedia, the free encyclopedia
This article is about the range in Oregon. For the larger grouping also known as the Coast Ranges, seePacific Coast Ranges.
Oregon Coast Range
Coast Range
The Northern Coast Range, seen fromSaddle MountaininClatsop County
Highest point
PeakMarys Peak
Elevation4,101 ft (1,250 m)
Coordinates44°30′16″N123°33′10″W/ 44.50444°N 123.55278°W/44.50444; -123.55278
Dimensions
Length200 mi (320 km) North–South
Geography
CountryUnited States
StateOregon
SubdivisionsNorthern Oregon Coast Range,Central Oregon Coast RangeandSouthern Oregon Coast Range
Parent rangePacific Coast Ranges
Borders onWillamette ValleyandKlamath Mountains(California Coast Ranges)
Geology
Age of rockPaleocene and Eocene
Type of rockvolcanic and forearc basin

TheOregon Coast Range,often called simply theCoast Rangeand sometimes thePacific Coast Range,is amountain range,in thePacific Coast Rangesphysiographic region,in theU.S. stateofOregonalong thePacific Ocean.This north-south running range extends over 200 miles (320 km) from theColumbia Riverin the north on the border of Oregon andWashington,south to themiddle fork of the Coquille River.It is 30 to 60 miles (48 to 97 km) wide and averages around 1,500 feet (460 m) in elevation abovesea level.The coast range has three main sections, a Northern, Central, and Southern.

The oldest portions of the range are over 60 million years old, with volcanics and aforearc basinas the primary mountain building processes responsible for the range. It is part of the larger grouping known as the Pacific Coast Ranges that extends over much of the western edge ofNorth Americafrom California to Alaska. The range creates arain shadoweffect for theWillamette Valleythat lies to the east of the mountains, creating a more stable climate and significantly less rain than the coastal region of the state. To the west where the range over-shadows theOregon Coast,the range causes more precipitation to fall on that side of the mountains, contributing to the numerous rivers that flow to the Pacific Ocean.

Marys Peakin the Central Coast Range is the highest peak at 4,097 feet (1,248 m). Logging is a major industry in the range in both private and government owned forests. Both the state and federal government manage forests in the Oregon Coast Range. The mountains are home to a variety of wildlife including black bear, elk, deer, beaver, many species of birds, and bats among others. Fish, including salmon and trout, and other aquatic life inhabit the streams and rivers flowing through the range.

Geology

[edit]
Exposedpillow lavain the Northern range

Volcanic activity approximately 66 million years ago in theCretaceousPeriod created offshoreislandsbeginning in the southern portion of the current range.[1]These Roseburg volcanics were followed by theSiletz River Volcanicsin the northern portions of the range, and lastly a series ofbasalt flowsfrom theColumbia River basaltsalso added to these formations with some smaller flows in-between.[1]Much of the formations are the result ofpillow basaltformations created when a hot basalt flow rapidly cooled upon meeting the salt water of the ocean.[1]These deposits offshore were then pushed into the continental plate as aforearc basinrotating slowly over millions of years.[1]This tectonic collision forced the basalt formations (and newer sedimentary rock formations that include marine terrace deposits) upward and created the coastal range.[1]

Additional basalt flows originated fromEastern Oregonand added to the layers that were uplifted, as the newerCascade Mountainshad not yet been formed.[1]By theEarly Oligoceneperiod c. 30 million years ago the current coastline was in place and erosion has continued to shape the range.[1]primarily through rivers cutting deep valleys through theigneousand sedimentary rocks.[1]

The geologic boundaries of the coast range formation extend from southwest Washington state in the north to around the Coquille River in the south where the older and tallerKlamath Mountainsbegin.[1]In the east the mountains begin as foothills forming the western edge of theWillamette Valleyand continue west to the coastline and beyond where the basalt formation tapers off into the continental shelf and ends at the continental slope with several banks and basins off shore.[1]

Physiographically, they are a section of the larger Pacific Border province, which in turn are part of the largerPacific Mountain Systemphysiographic division.

Climate

[edit]
Snow onSouth Saddle Mountain

A mild maritime climate prevails throughout the range with temperature and precipitation varying due to elevation and distance from the coastline.[2]Characteristics of theclimateinclude cool dry summers followed by mild and wet winters.[2]The majority of precipitation accumulates in the form ofrain,with snow during the winter months at the higher elevations, but no permanentsnow pack.[2]Annual precipitation differs from 60 inches (1,500 mm) in some parts to up to 120 inches (3,000 mm), with the higher amounts coming in the higher elevations.[2]The average high temperature in January is 36.3 °F (2.4 °C), and the average high in July is 61.9 °F (16.6 °C) with temperatures also varying by elevation.[2]The further inland and the more southerly portions have a more Mediterranean climate that is more similar to the climate of the Willamette Valley. The Coast Range creates arain shadoweffect byforcing moisture laden clouds to riseby expelling moisture.[3]This shields the Willamette Valley and causes a less maritime climate with hotter summers and less precipitation than the Oregon Coast.[4]

Sections

[edit]
Road through the Northern section showing the mix of deciduous and coniferous trees

The Oregon Coast Range is divided into three separate sections: North, Central, and South. In the south is the oldest portion of the range with formation beginning in the Paleocene era with the Roseburg volcanics, while the newest section is the northernmost portion formed first with the Siletz River Volcanics.[1]The Central and Northern sections contain more sedimentary rocks from the mud, silt, sand, and other volcanic debris than the lower Southern section.[1]Also, the Oregon Coast Range is home to over 50 mammal species, over 100 species of birds, and nearly 30 reptile or amphibian species that spent significant portions of their life cycle in the mountains.[5]

North

[edit]
Main article:Northern Oregon Coast Range

Located in the northwest portion ofOregonthis section of the range has peaks as high as 3,706 feet (1,130 m) forRogers Peak.[6]Forests here are considered to be some of the most productive timber land in the world.[7]Trees include primarilySitka spruce,western redcedar,Douglas-fir,andwestern hemlock.[8]Other plants include huckleberry, salmonberry, salal, vine maple,Oregon grape,bracken fern, and thimble-berry among others.[8][9]The northern boundary is theColumbia River,with some mountainous features on the north side of the river, and continues south for approximately 100 miles (160 km) to theSalmon RiverwhereOregon Route 18crosses the range from the Willamette Valley to theOregon Coastwith width roughly 35 miles (60 km).[7]

Central

[edit]
ASitka sprucetree logged nearNewportin 1918
Main article:Central Oregon Coast Range

Located between theSalmon Riverand theUmpqua Riveron the north and south, the Central range is bounded by theWillamette Valleyon the east and thePacific Oceanto the west. This approximately 90-mile (140 km)[10]long mountain range contains mountains as high as 4,097 feet (1,248 m) forMarys Peak.[11]Portions of the range are inside theSiuslaw National Forestalong with three designated wilderness areas:Drift Creek Wilderness,Cummins Creek Wildernessand theRock Creek Wilderness.Larger animals that live in these section include deer, elk, bobcat, and bear.[12]Bear areblack bearwhile deer aremuleandblack-tailed deerspecies. Other mammals here aremountain beaver,beavers, coyote, mink,river otter,mountain lion, porcupines, skunks, and brush rabbit.[5]

South

[edit]
Main article:Southern Oregon Coast Range

The southernmost section of the Coast Range is located in the southwest portion of Oregon between themiddle fork of the Coquille Riverin the south and theUmpqua Riveron the north.Oregon Route 38is the general divide between the Central and Southern portions of the Coast Range. Approximately 55 miles (90 km) long, the section contains mountains as high as 3,547 feet (1,081 m) forBone Mountain.[13]On the south theCoquille River’s middle fork provides the general dividing line between the Central Range and theKlamath Mountainsto the south and east.[1]

Birds living in the Southern Coast Range include a variety of smaller and larger bird species.[2]Species includeperegrine falcons,pileated woodpeckers,olive-sided flycatcher, and western bluebirds among others.[14]Thethreatenednorthern spotted owlalso inhabit the mountain forests.[15]Animal life in the rivers, streams, and lakes includelamprey,coastal cutthroattrout,dace,Umpqua chub, frogs, salamander, turtles,coho salmon,steelhead trout,and others.[14]

Peaks

[edit]
Marys Peak

Five tallest peaks in the Oregon Coast Range:

Rivers

[edit]
Map of the region with major rivers in blue; orange line shows divide between watersheds

The following rivers have their headwaters in the Oregon Coast Range:

Nestucca Riverin the Northern range

See also

[edit]

References

[edit]
  1. ^abcdefghijklmOrr, Elizabeth and William Orr, and Ewart Baldwin. Geology of Oregon. Kendall/Hunt Publishing, 1992, 4th edition.
  2. ^abcdefMcGarigal, Kevin; William C. McComb (August 1995). "Relationships Between Landscape Structure and Breeding Birds in the Oregon Coast Range".Ecological Monographs.65(3). The Ecological Society of America: 235–260.doi:10.2307/2937059.JSTOR2937059.
  3. ^Encyclopædia Britannica: orographic precipitation
  4. ^Encyclopædia Britannica: Oregon climate
  5. ^abNorthwest Forest Plan: Wildlife Habitat Relationships for the Coast Guide.Archived2007-09-27 at theWayback Machine
  6. ^Peakbagger: Rogers Peak
  7. ^abOregon State University: Northern Coast Range Adaptive Management Area; Chapter 2: Physical and Biological Environment
  8. ^abTree Dictionary: From the Forest to the Sea: A Story of Fallen Trees
  9. ^Biotic Aspection in the Coast Range Mountains of Northwestern Oregon, Ecological Monographs, Vol. 28, No. 1. (Jan., 1958), pp. 21–54. James A. Macnab.
  10. ^Peakbagger: Central Oregon Coast Range
  11. ^"Marys Peak".Geographic Names Information System.United States Geological Survey,United States Department of the Interior.Retrieved2009-02-19.
  12. ^Kerr, Andy. 1980. Last Stand for Oregon's Coast Range. Not Man Apart. Vol. 10, No. 1. January. 7.Archived2009-01-01 at theWayback Machine
  13. ^"Bone Mountain".Geographic Names Information System.United States Geological Survey,United States Department of the Interior.Retrieved2009-02-19.
  14. ^abFish and Wildlife Service: Notice of intent, to conduct scoping meetings
  15. ^Spotted Owl Home Range and Habitat Use in Southern Oregon Coast Ranges
  16. ^"Grass Mtn Lot".NGS Data Sheet.National Geodetic Survey,National Oceanic and Atmospheric Administration,United States Department of Commerce.Retrieved2008-11-07.
  17. ^"Laurel".NGS Data Sheet.National Geodetic Survey,National Oceanic and Atmospheric Administration,United States Department of Commerce.Retrieved2008-11-07.
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Oregon_Coast_Range&oldid=1191253377"