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29-732: It rises in the Central Oregon Coast Range in western Lane County , approximately 10 mi (16 km) west of Veneta . It flows east through the mountains to Veneta, through the Fern Ridge Reservoir , and then north into the Willamette Valley, roughly parallel to and west of the Willamette River. It joins the Willamette from the southwest approximately 4 mi (6.5 km) west of Halsey . The Fern Ridge Reservoir

58-484: Is 0 ° 07′, and typically steeper closer to the coastline than it is near the shelf break. At the shelf break begins the continental slope, which can be 1–5 km above the deep-ocean floor. The continental slope often exhibits features called submarine canyons . Submarine canyons often cut into the continental shelves deeply, with near vertical sides, and continue to cut the morphology to the abyssal plain . These canyons are often V-shaped, and can sometime enlarge onto

87-426: Is known as the continental borderland . Passive margins are often located in the interior of lithospheric plates, away from the plate boundaries, and lack major tectonic activity. They often face mid-ocean ridges . From this, comes a wide variety of features, such as low-relief land extending miles away from the beach, long river systems and piles of sediment accumulating on the continental shelf. The East Coast of

116-524: Is often still preserved closer to shore, continental shelves show high levels of glacial and relict sediments, deposited when sea level was lower. Often found on passive margins are several kilometres of sediment, consisting of terrigenous and carbonate ( biogenous ) deposits. These sediment reservoirs are often useful in the study of paleoceanography and the original formation of ocean basins. These deposits are often not well preserved on active margin shelves due to tectonic activity. The continental shelf

145-418: Is one of the three major zones of the ocean floor , the other two being deep-ocean basins and mid-ocean ridges . The continental margin consists of three different features: the continental rise , the continental slope , and the continental shelf . Continental margins constitute about 28% of the oceanic area. The continental shelf is the relatively shallow water area found in proximity to continents; it

174-422: Is part of a large forearc basin that extends for much of the entire Coast Range on a north-south alignment. Parts of the upper portions of the range contain continental margin deposits from the early Eocene to Paleocene age. Portions of this include marine fossils in the geologic record. Sandstone and shale are also present in the sections of the mountains, with thickness up to 7,875 ft (2,400 m). In

203-785: Is the middle section of the Oregon Coast Range , in the Pacific Coast Ranges physiographic region , and located in the west-central portion of the state of Oregon , United States roughly between the Salmon River and the Umpqua River and the Willamette Valley and the Pacific Ocean . This approximately 90-mile (140 km) long mountain range contains mountains as high as 4,097 feet (1,226 m) for Marys Peak . Portions of

232-569: Is the most economically valuable part of the ocean. It often is the most productive portion of the continental margin, as well as the most studied portion, due to its relatively shallow, accessible depths. Due to the rise of offshore drilling , mining and the limitations of fisheries off the continental shelf, the United Nations Convention on the Law of the Sea (UNCLOS) was established. The edge of

261-413: Is the portion of the continental margin that transitions from the shore out towards to ocean. Continental shelves are believed to make up 7% of the sea floor. The width of continental shelves worldwide varies in the range of 0.03–1500 km . The continental shelf is generally flat, and ends at the shelf break , where there is a drastic increase in slope angle: The mean angle of continental shelves worldwide

290-664: The Central Coast Range include chinook salmon, steelhead, cutthroat trout, and the threatened species coho salmon . A large section of the range is covered by the Siuslaw National Forest. Most of the range is forested and mainly within the western hemlock vegetation zone with the overstory of the forest dominated by red alder , western hemlock, western cedar, bigleaf maple, and Douglas-fir trees. In these forested sections, trees include Sitka spruce, western redcedar, Douglas-fir, and western hemlock. The understory of

319-538: The Long Tom Watershed Council to protect and restore the river. The river's name, Long Tom, developed gradually during the 19th century in imitation of a native tribal group called Lung-tum-ler . The Native American name of this Kalapuyan group is [lámpʰtumpif] , literally meaning "spank-his-ass". Named tributaries from source to mouth are Micheals, Jones, Swamp, Dusky, Hayes, Sweet, Green, and Gold creeks. Then come Noti, Wilson, Indian creeks before

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348-473: The United States is an example of a passive margin. These margins are much wider and less steep than active margins. As continental crust weathers and erodes, it degrades into mainly sands and clays . Many of these particles end up in streams and rivers that then dump into the ocean. Of all the sediment in the stream load, 80% is then trapped and dispersed on continental margins. While modern river sediment

377-509: The area, including residents in the city of Veneta and the rural farming communities of Alvadore , Cheshire , Crow , Franklin, and Noti , as well as industrial and commercial land on the western edge of Eugene. These lands were inhabited by the Chelamela group of the Kalapuya Indians prior to European settlement. The Oregon Country Fair is one of many groups and agencies that work with

406-606: The average high in July is 61.9 °F (16.6 °C) with temperature also varying by elevation. All peaks in the range over 3,000 feet (910 m) in elevation. The following rivers have portions of their headwaters in the Central Oregon Coast Range: Drains to Willamette River : Drains to Pacific Ocean : Continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters . It

435-1088: The common raccoon, common porcupine, brush rabbit, and skunk. The coast range is inhabited by eleven different species of bats , and they account for nearly 20% of all the mammal species in the range. Species of bats include the Yuma myotis , silver-haired bat, big brown bat, hoary bat, and the long-eared myotis. Other mammals living in the central range include beavers , creeping voles, long-tailed voles, vagrant shrews, deer mice, Pacific jumping mice, western pocket gopher, marsh shrew, shrew-mole, coast-mole, ermine, northern flying squirrel , and Townsend's chipmunk among others. Amphibians include, but are not limited to, rough-skinned newts, northwestern salamanders, western red-backed salamander , Coastal tailed frog, Coastal giant salamander, red-legged frog, southern torrent salamander, and Ensatina . Additional species include northwestern garter snake, northern alligator lizard, Pacific tree frog , western pond turtles, gopher snake, ringneck snake, and western fence lizards. Fish species in

464-533: The continental margin is one criterion for the boundary of the internationally recognized claims to underwater resources by countries in the definition of the " continental shelf " by the UNCLOS (although in the UN definition the "legal continental shelf" may extend beyond the geomorphological continental shelf and vice versa). Such resources include fishing grounds, oil and gas accumulations, sand, gravel, and some heavy minerals in

493-921: The continental shelf. At the base of the continental slope, there is a sudden decrease in slope angle, and the sea floor begins to level out towards the abyssal plain. This portion of the seafloor is called the continental rise , and marks the outermost zone of the continental margin. There are two types of continental margins: active and passive margins. Active margins are typically associated with lithospheric plate boundaries. These active margins can be convergent or transform margins, and are also places of high tectonic activity, including volcanoes and earthquakes . The West Coast of North America and South America are active margins. Active continental margins are typically narrow from coast to shelf break, with steep descents into trenches . Convergent active margins occur where oceanic plates meet continental plates. The denser oceanic crust of one plate subducts below

522-417: The forest areas contain vine maple, Oregon grape , salmonberry, huckleberry, and sword fern to name a few. Other plants that grow in the region are Pacific madrone, salmonberry, Pacific silver fir, bracken fern, manzanita, thimble-berry, Pacific dogwood , bitter cherry, snowberry, some rose species, and cascara. Additionally, various grass, sedge, and moss species are some of the other plant life growing in

551-820: The hillsides from the erosion. Unlike many areas in North America, the mountain range did not see glaciations during the Pleistocene age. 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 Central Coast Range include a variety of smaller and larger bird species. These include winter wrens, chestnut-backed chickadees, red-breasted nuthatches , varied thrushes, several swallow species, red crossbills, evening grosbeaks, brown creepers, olive-sided flycatchers, Hammond's flycatchers, gray jays, western wood-pewees, and western tanagers. Some of

580-450: The larger species in the range include the red-breasted sapsucker, common ravens, peregrine falcons, the pileated woodpecker , turkey vultures, wood duck, common nighthawks, and the red-tailed hawk. Birds in lower numbers include Vaux's swifts, the endangered spotted owl , bald eagles, the downy woodpecker, hairy woodpeckers, the pine siskin, the hermit warbler , Pacific-slope flycatchers, golden-crowned kinglets, and ruffed grouse. One of

609-453: The less dense continental crust of another plate. Convergent active margins are the most common type of active margin. Transform active margins are more rare, and occur when an oceanic plate and a continental plate are moving parallel to each other in opposite directions. These transform margins are often characterized by many offshore faults , which causes high degree of relief offshore, marked by islands , shallow banks, and deep basins . This

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638-504: The more common avian wildlife is the American dipper, which live mainly near rivers and streams. These birds build nests from six to nine inches (229 mm) in diameter out of moss. The central coast range is also home to some larger animals such as deer, elk, bobcat, and bear. Bear are black bear while deer are mule and black-tailed deer species. Some additional mammals are mountain beaver , coyote, mink, river otter , mountain lion,

667-682: The mountain range. Arthropods include various spiders, millipedes, collembolans, beetles, and a variety of centipedes. The range begins around the Salmon River with the Northern Oregon Coast Range to the north. Oregon Route 18 is the general divide between the two sections. On the southern end the Umpqua River and Oregon Route 38 provide the general dividing line between the Central and Southern Oregon Coast Range . The climate of

696-561: The mountains are approximately 50 to 60 million years old. It is theorized that the source of these lava flows came from oceanic islands that formed over a tectonic hotspot. The entire Oregon Coast Range overlies a convergent tectonic margin that interacts with the Juan de Fuca Plate that is being sub-ducted beneath the North America tectonic plate. This is the Cascadia subduction zone that has experienced uplift for several million years. Currently it

725-466: The mountains is of the mild maritime variety. It is characterized by cool dry summers followed by mild and wet winters. Most precipitation falls in the form of rain, with snow during the winter months at the higher elevations. Annual precipitation varies from 60 to 120 inches (150–300 cm), with more in the higher elevations. The average high temperature in January is 36.3 °F (2.4 °C), and

754-677: The range are inside the Siuslaw National Forest and three wilderness areas exist as well: Drift Creek Wilderness , Cummins Creek Wilderness and Rock Creek Wilderness . The underlying rock of the Central Coast Range are the igneous rocks from the Siletz River Volcanics of the Paleocene age. It is estimated that this rock formation is up to 16 miles (26 km) thick. These formations consist mainly of pillow basalt , large lava flows, tuff-breccia, and sills. This part of

783-528: The river enters Fern Ridge Reservoir. Hannavan and Inman creeks enter the reservoir as does Coyote Creek . (The topographic map also shows a separate Coyote Creek that leaves the reservoir south of the main Long Tom channel and rejoins it further downstream.) Below the reservoir come Squaw, the second confluence with Coyote Creek, then Lingo Slough, Bear, Amazon , Ferguson, Shafer, and Miller creeks. Central Oregon Coast Range The Central Oregon Coast Range

812-448: The southern part of the range the bedrock is overlaid by Eocene age turbidite sediments and river sediment. The active tectonic forces have created many faults and folds in the range. Additionally, erosion is a major landscape-shaping force for the range. Both heavy rainfall and the resulting landslides have worked to erode and shape the mountains. Much of the landscape is dominated by steep slopes and drainages that are deeply cut into

841-472: Was created in 1942 when the United States Army Corps of Engineers dammed the river to control flooding. The watershed includes approximately 410 sq mi (1,100 km) of land (262,000 acres, 1060 km) zoned as 45 percent forest, 30 percent agricultural, 8 public, and 17 percent urban or rural residential. The Long Tom waters support more than 140,000 people in

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