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126-721: The Eastbank Esplanade (officially Vera Katz Eastbank Esplanade ) is a pedestrian and bicycle path along the east shore of the Willamette River in Portland , Oregon , United States. Running through the Kerns , Buckman , and Hosford-Abernethy neighborhoods, it was conceived as an urban renewal project to rebuild the Interstate 5 bicycle bypass washed out by the Willamette Valley Flood of 1996 . It
252-562: A flood in 1861 . This and many other large flows preceded the Flood Control Act of 1936 and dam construction on the Willamette's major tributaries. The river below Willamette Falls, 26.5 miles (42.6 km) from the mouth, is affected by semidiurnal tides , and gauges have detected reverse flows (backwards river flows) below Ross Island at RM 15 (RK 24). The National Weather Service issues tide forecasts for
378-825: A mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from
504-408: A planet's formation , it would have experienced heating from impacts from planetesimals , which would have dwarfed even the asteroid impact that caused the extinction of dinosaurs . This heating could trigger differentiation , further heating the planet. The larger a body is, the slower it loses heat. In larger bodies, for example Earth, this heat, known as primordial heat, still makes up much of
630-499: A common feature at explosive volcanoes on Earth. Pyroclastic flows have been found on Venus, for example at the Dione Regio volcanoes. A phreatic eruption can occur when hot water under pressure is depressurised. Depressurisation reduces the boiling point of the water, so when depressurised the water suddenly boils. Or it may happen when groundwater is suddenly heated, flashing to steam suddenly. When water turns into steam in
756-425: A lava flow to cool rapidly. This splinters the surface of the lava, and the magma then collects into sacks that often pile up in front of the flow, forming a structure called a pillow. A’a lava has a rough, spiny surface made of clasts of lava called clinkers. Block lava is another type of lava, with less jagged fragments than in a’a lava. Pahoehoe lava is by far the most common lava type, both on Earth and probably
882-409: A mechanical standpoint it is a water filled crevasse turned upside down. As magma rises into the vertical crack, the low density of the magma compared to the wall rock means that the pressure falls less rapidly than in the surrounding denser rock. If the average pressure of the magma and the surrounding rock are equal, the pressure in the dike exceeds that of the enclosing rock at the top of the dike, and
1008-553: A moon of Saturn . The ejecta may be composed of water, liquid nitrogen , ammonia , dust, or methane compounds. Cassini–Huygens also found evidence of a methane-spewing cryovolcano on the Saturnian moon Titan , which is believed to be a significant source of the methane found in its atmosphere. It is theorized that cryovolcanism may also be present on the Kuiper Belt Object Quaoar . A 2010 study of
1134-510: A partially molten core. However, the Moon does have many volcanic features such as maria (the darker patches seen on the Moon), rilles and domes . The planet Venus has a surface that is 90% basalt , indicating that volcanism played a major role in shaping its surface. The planet may have had a major global resurfacing event about 500 million years ago, from what scientists can tell from
1260-480: A phreatic eruption, it expands at supersonic speeds, up to 1,700 times its original volume. This can be enough to shatter solid rock, and hurl rock fragments hundreds of metres. A phreatomagmatic eruption occurs when hot magma makes contact with water, creating an explosion. One mechanism for explosive cryovolcanism is cryomagma making contact with clathrate hydrates . Clathrate hydrates, if exposed to warm temperatures, readily decompose. A 1982 article pointed out
1386-470: A plan to improve fish passage and take other actions to help native fish recover in 2008. Since then, work has proceeded slowly, and the Corps of Engineers, citing engineering difficulties and cost, may not meet the original agreed-upon deadline of 2023 for a system of effective remedies. Other major dams in the Willamette watershed are owned by other interests; for example, several hydroelectric facilities on
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#17327900791871512-404: A power plant. The locks at Willamette Falls were completed in 1873. Elsewhere on the main stem, numerous minor flow-regulation structures force the river into a narrower and deeper channel to facilitate navigation and flood control . The dams on the Willamette's major tributaries are primarily large flood-control, water-storage, and power-generating dams. Thirteen of these dams were built from
1638-499: A pressure of 0.208 GPa is reached, after which the melting point increases with pressure. Flux melting occurs when the melting point is lowered by the addition of volatiles, for example, water or carbon dioxide. Like decompression melting, it is not caused by an increase in temperature, but rather by a decrease in melting point. Cryovolcanism , instead of originating in a uniform subsurface ocean, may instead take place from discrete liquid reservoirs. The first way these can form
1764-494: A rigid open channel, in the lithosphere and settles at the level of hydrostatic equilibrium . Despite how it explains observations well (which newer models cannot), such as an apparent concordance of the elevation of volcanoes near each other, it cannot be correct and is now discredited, because the lithosphere thickness derived from it is too large for the assumption of a rigid open channel to hold. Unlike silicate volcanism, where melt can rise by its own buoyancy until it reaches
1890-523: A system of parks, trails, and wildlife refuges along the river. In 1998, the Willamette became one of 14 rivers designated an American Heritage River by U.S. President Bill Clinton . By 2007 the Greenway had grown to include more than 170 separate land parcels, including 10 state parks. Public uses of the river and land along its shores include camping, swimming, fishing, boating, hiking, bicycling, and wildlife viewing. In 2008, government agencies and
2016-467: A temporary lake, Lake Allison , that stretched from Lake Oswego to near Eugene. The ancestral Tualatin Valley, part of the Willamette basin, flooded as well; water depths ranged from 200 feet (61 m) at Lake Oswego to 100 feet (30 m) as far upstream (west) as Forest Grove . Flood deposits of silt and clay, ranging in thickness from 115 feet (35 m) in the north to about 15 feet (4.6 m) in
2142-400: Is Portland, with more than 500,000 residents. Not all of these cities draw water in part or exclusively from the Willamette for their municipal water supply. Other cities in the watershed (but not on the main-stem river) with populations of 20,000 or more are Gresham, Hillsboro, Beaverton, Tigard, McMinnville, Tualatin, Woodburn , and Forest Grove. Sixty-four percent of the watershed
2268-428: Is a plume of warm ice welling up and then sinking back down, forming a convection current. A model developed to investigate the effects of this on Europa found that energy from tidal heating became focused in these plumes, allowing melting to occur in these shallow depths as the plume spreads laterally (horizontally). The next is a switch from vertical to horizontal propagation of a fluid filled crack. Another mechanism
2394-447: Is driven by exsolution of volatiles that were previously dissolved into the cryomagma, similar to what happens in explosive silicate volcanism as seen on Earth, which is what is mainly covered below. Silica-rich magmas cool beneath the surface before they erupt. As they do this, bubbles exsolve from the magma. As the magma nears the surface, the bubbles and thus the magma increase in volume. The resulting pressure eventually breaks through
2520-609: Is entirely in the form of water, which freezes into ice on the frigid surface. This process is known as cryovolcanism , and is apparently most common on the moons of the outer planets of the Solar System . In 1989, the Voyager 2 spacecraft observed cryovolcanoes (ice volcanoes) on Triton , a moon of Neptune , and in 2005 the Cassini–Huygens probe photographed fountains of frozen particles erupting from Enceladus ,
2646-477: Is formed when fluids and gases under pressure erupt to the surface, bringing mud with them. This pressure can be caused by the weight of overlying sediments over the fluid which pushes down on the fluid, preventing it from escaping, by fluid being trapped in the sediment, migrating from deeper sediment into other sediment or being made from chemical reactions in the sediment. They often erupt quietly, but sometimes they erupt flammable gases like methane. Cryovolcanism
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#17327900791872772-512: Is from Albany to Oregon City. At Willamette Falls , between West Linn and Oregon City, the river plunges about 40 feet (12 m). For the rest of its course, the river is extremely low-gradient and is affected by Pacific Ocean tidal effects from the Columbia. The main stem of the Willamette varies in width from about 330 to 660 feet (100 to 200 m). With an average flow at the mouth of about 37,400 cubic feet per second (1,060 m /s),
2898-497: Is heating of ice from release of stress through lateral motion of fractures in the ice shell penetrating it from the surface, and even heating from large impacts can create such reservoirs. When material of a planetary body begins to melt, the melting first occurs in small pockets in certain high energy locations, for example grain boundary intersections and where different crystals react to form eutectic liquid , that initially remain isolated from one another, trapped inside rock. If
3024-503: Is much more than the ambient pressure. Not only that, but any volatiles in the water will exsolve. The combination of these processes will release droplets and vapor, which can rise up the fracture, creating a plume. This is thought to be partially responsible for Enceladus's ice plumes. On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example,
3150-635: Is of indigenous origin, deriving from the French pronunciation of the name of a Clackamas Native American village. However, Native American languages in Oregon were very similar, so the name may also be derived from Kalapuya dialects. Around the year 1850, the Kalapuya numbered between 2,000 and 3,000 and were distributed among several groups. These figures are only speculative; there may have been as few as eight subgroups or as many as 16. In that time period,
3276-460: Is pressurised in the same way. For a crack in the ice shell to propagate upwards, the fluid in it must have positive buoyancy or external stresses must be strong enough to break through the ice. External stresses could include those from tides or from overpressure due to freezing as explained above. There is yet another possible mechanism for ascent of cryovolcanic melts. If a fracture with water in it reaches an ocean or subsurface fluid reservoir,
3402-577: Is privately owned, while 36 percent is publicly owned. The U.S. Forest Service manages 30 percent of the watershed, the U.S. Bureau of Land Management 5 percent, and the State of Oregon 1 percent. Sixty-eight percent of the watershed is forested; agriculture, concentrated in the Willamette Valley, makes up 19 percent, and urban areas cover 5 percent. More than 81,000 miles (130,000 km) of roads criss-cross
3528-461: Is the eruption of volatiles into an environment below their freezing point. The processes behind it are different to silicate volcanism because the cryomagma (which is usually water-based) is normally denser than its surroundings, meaning it cannot rise by its own buoyancy. Sulfur lavas have a different behaviour to silicate ones. First, sulfur has a low melting point of about 120 degrees Celsius. Also, after cooling down to about 175 degrees Celsius
3654-886: The Clackamas River are owned by Portland General Electric . These include the River Mill Hydroelectric Project , the Oak Grove project, and the dam at Timothy Lake . The 50 or so crossings of the Willamette River include many historic structures, such as the Van Buren Street Bridge , a swing bridge . Built in 1913, it carries Oregon Route 34 (Corvallis–Lebanon Highway) over the river upstream of RM 131 (RK 211) in Corvallis. The machinery to operate
3780-570: The Coast Fork Willamette River , and Dorena on the Row River . Due to these tall dams, Chinook salmon and steelhead are blocked from roughly half of their historic habitat and spawning grounds on the Willamette's major tributaries. Unable to live and reproduce as they once did, they have been "brought to the brink of extinction". Endangered species listings and a subsequent lawsuit by Willamette Riverkeeper led to
3906-612: The Farallon Plate beneath the North American Plate , creating the forearc basin that would later become the Willamette Valley. The valley was initially part of the continental shelf , rather than a separate inland sea. Many layers of marine deposits formed in the forearc basin and cover the older Siletz River Volcanics. About 20 to 16 million years ago, uplift formed the Coast Range and separated
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4032-559: The Hawthorne Bridge ( 45°30′46″N 122°40′05″W / 45.512804°N 122.668059°W / 45.512804; -122.668059 ( Esplanade south end under Hawthorne Bridge ) ). The south end connects to the Springwater Corridor , a rail trail that runs south to Sellwood , then east to Gresham , then south to Boring . The esplanade includes a 1,200-foot (370 m) floating walkway,
4158-642: The Missoula Floods —a series of large outpourings originating at Glacial Lake Missoula in Montana—swept down the Columbia River and backfilled the Willamette watershed. Each flood produced "discharges that exceeded the annual discharge of all the present-day rivers of the world combined". Filling the Willamette basin to depths of 400 feet (120 m) in the Portland region, each flood created
4284-678: The Oregon State Capitol in Salem. Evidence suggests that massive quakes of 8 or more on the Richter scale have occurred historically in the Cascadia subduction zone off the Oregon coast, most recently in 1700 CE , and that others as strong as 9 on the Richter scale occur every 500 to 800 years. The basin's high population density, its nearness to this subduction zone, and its loose soils, which tend to amplify shaking, make
4410-505: The Oregon Trail . The river was an important transportation route in the 19th century, although Willamette Falls , just upstream from Portland, was a major barrier to boat traffic. In the 21st century, major highways follow the river, and roads cross the main stem on approximately 30 different bridges. More than half a dozen bridges not open to motorized vehicles provide separate crossings for bicycles and pedestrians, mostly in
4536-687: The Sandy River did the explorers learn about their oversight. William Clark returned down the Columbia and entered the Willamette River in April 1806. Fur trappers originally working for the Pacific Fur Company (PFC)) and subsequently for the North West Company (NWC) were next to visit the Willamette River and various tributaries. The Siskiyou Trail (or California-Oregon Trail) originally developed by Indigenous people,
4662-857: The Siletz , the Nestucca , the Trask , and the Wilson to the west; the Nehalem and the Clatskanie to the northwest, and the Columbia River to the north. About 2.5 million people lived in the Willamette River basin as of 2010, about 65 percent of the population of Oregon. As of 2009, the basin contained 20 of the 25 most populous cities in Oregon. These cities include Springfield, Eugene, Corvallis, Albany, Salem, Keizer, Newberg, Oregon City, West Linn, Milwaukie, Lake Oswego, and Portland. The largest
4788-415: The U.S. federal government . The main channel, which is the primary navigational conduit for Portland's harbor and riverside industrial areas, is 40 feet (12 m) deep and varies in width from 600 to 1,900 feet (180 to 580 m), although the river broadens to 2,000 feet (610 m) in some of its lower reaches. This channel enters the Columbia about 101 miles (163 km) from the Columbia's mouth on
4914-436: The contact angle of the melted material allows the melt to wet crystal faces and run along grain boundaries , the melted material will accumulate into larger quantities. On the other hand, if the angle is greater than about 60 degrees, much more melt must form before it can separate from its parental rock. Studies of rocks on Earth suggest that melt in hot rocks quickly collects into pockets and veins that are much larger than
5040-644: The core–mantle boundary , 3,000 kilometers (1,900 mi) deep within Earth. This results in hotspot volcanism , of which the Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. In 1912–1952, in the Northern Hemisphere, studies show that within this time, winters were warmer due to no massive eruptions that had taken place. These studies demonstrate how these eruptions can cause changes within
5166-609: The eastern United States , mainly the Upland South borderlands of Missouri, Iowa, and the Ohio Valley. Many of these emigrants followed the Oregon Trail , a 2,170-mile (3,490 km) trail across western North America that began at Independence, Missouri , and ended at various locations near the mouth of the Willamette River. Although people had been traveling to Oregon since 1836, large-scale migration did not begin until 1843, when nearly 1,000 pioneers headed westward. Over
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5292-405: The grain size, in contrast to the model of rigid melt percolation . Melt, instead of uniformly flowing out of source rock, flows out through rivulets which join to create larger veins. Under the influence of buoyancy , the melt rises. Diapirs may also form in non-silicate bodies, playing a similar role in moving warm material towards the surface. A dike is a vertical fluid-filled crack, from
5418-526: The main stem Willamette meanders generally north for 187 miles (301 km) to the Columbia River . The river's two most significant course deviations occur at Newberg , where it turns sharply east, and about 18 miles (29 km) downstream from Newberg, where it turns north again. Near its mouth north of downtown Portland , the river splits into two channels that flow around Sauvie Island . Used for navigation purposes, these channels are managed by
5544-405: The terrestrial planets , and the Moon, experience some of this heating. The icy bodies of the outer solar system experience much less of this heat because they tend to not be very dense and not have much silicate material (radioactive elements concentrate in silicates). On Neptune's moon Triton , and possibly on Mars, cryogeyser activity takes place. The source of heat is external (heat from
5670-606: The 1940s through the 1960s and are operated by the United States Army Corps of Engineers (USACE). Of those 13, 9 produce hydropower. Flood-control dams operated by the USACE are estimated to hold up to 27 percent of the Willamette's runoff. They are used to regulate river flows so as to cut peaks off floods and increase low flows in late summer and autumn, and to divert water into deeper, narrower channels to prevent flooding. A relatively small of amount of
5796-453: The 1960s, Oregon Governor Tom McCall led a push for stronger pollution controls on the Willamette. In this, he was encouraged by Robert (Bob) Straub —the state treasurer and future Oregon governor (1975)—who first proposed a Willamette Greenway program during his 1966 gubernatorial campaign against McCall. The Oregon State Legislature established the program in 1967. Through it, state and local governments cooperated in creating or improving
5922-825: The Cascade Range to 10 feet (3.0 m) at the mouth on the Columbia River. Watersheds bordering the Willamette River basin are those of the Little Deschutes River to the southeast, the Deschutes River to the east, and the Sandy River to the northeast; the North Umpqua and Umpqua rivers to the south; coastal rivers including (from south to north) the Siuslaw , the Alsea , the Yaquina ,
6048-472: The City of Portland and the State of Oregon to dramatically reduce combined sewer overflows (CSOs) led to Portland's Big Pipe Project . The project, part of a related series of Portland CSO projects completed in late 2011 at a cost of $ 1.44 billion, separates the city's sanitary sewer lines from storm-water inputs that sometimes overwhelmed the combined system during heavy rains. When that occurred, some of
6174-603: The Clackamas' tribal population was roughly 1,800. The U.S. Census Bureau estimated that the Chinook population was nearly 5,000, though not all of the Chinook lived on the Willamette. The Chinook territory encompassed the lower Columbia River valley and significant stretches of the Pacific coast on both the north and the south side of the Columbia's mouth. At times, however, the Chinook territory extended even farther south in
6300-478: The Columbia River. Between the 1850s and the 1960s, channel-straightening and flood control projects, as well as agricultural and urban encroachment, cut the length of the river between the McKenzie River confluence and Harrisburg by 65 percent. Similarly, the river was shortened by 40 percent in the stretch between Harrisburg and Albany. Interstate 5 and three branches of Oregon Route 99 are
6426-554: The Columbia to Bachelor Island . Rockwell's survey was extremely detailed, including 17,782 hydrographic soundings. His work helped open the port of Portland to commerce. In the second half of the 19th century, the USACE dredged channels and built locks and levees in the Willamette's watershed. Although products such as lumber were often transported on an existing network of railroads in Oregon, these advances in navigation helped businesses deliver more goods to Portland, feeding
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#17327900791876552-693: The Columbia's flow. The Willamette's main stem is 187 miles (301 km) long, lying entirely in northwestern Oregon in the United States. Flowing northward between the Oregon Coast Range and the Cascade Range , the river and its tributaries form the Willamette Valley , a basin that contains two-thirds of Oregon's population, including the state capital, Salem , and the state's largest city, Portland , which surrounds
6678-463: The Earth's atmosphere. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Earth's Moon has no large volcanoes and no current volcanic activity, although recent evidence suggests it may still possess
6804-798: The Eugene area, and several others are exclusively for rail traffic. There are also ferries that convey cars, trucks, motorcycles, bicycles, and pedestrians across the river for a fare and provided river conditions permit. They are the Buena Vista Ferry between Marion County and Polk County south of Independence and Salem, the Wheatland Ferry between Marion County and Polk County north of Salem and Keizer, and Canby Ferry in Clackamas County north of Canby. Since 1900, more than 15 large dams and many smaller ones have been built in
6930-569: The European Mars Express spacecraft has found evidence that volcanic activity may have occurred on Mars in the recent past as well. Jupiter 's moon Io is the most volcanically active object in the Solar System because of tidal interaction with Jupiter. It is covered with volcanoes that erupt sulfur , sulfur dioxide and silicate rock, and as a result, Io is constantly being resurfaced. There are only two planets in
7056-788: The HBC merged with the NWC. In 1825 a new Fort Vancouver headquarters was built on the north shore of the Columbia closer to the Willamette, and Fort George was closed. Alexander Roderick McLeod traveled up the Willamette in 1826 and 1827, to the Umpqua and the Rogue rivers. In 1829 Lucier established a land claim near the Champoeg trading post and started to settle, soon joined by Gervais (1831), Pierre Belleque (1833) and 77 French Canadian settlers by 1836. By 1843, approximately 100 newcomer families lived in
7182-519: The Middle and Coast forks and the McKenzie , Long Tom , Marys , Calapooia , Santiam , Luckiamute , Yamhill , Molalla , Tualatin , and Clackamas rivers. Beginning at 438 feet (134 m) above sea level, the main stem descends 428 feet (130 m) between source and mouth, or about 2.3 feet per mile (0.4 m per km). The gradient is slightly steeper from the source to Albany than it
7308-419: The Native Americans. Upper-river tribes caught steelhead and salmon, often by building weirs across tributary streams. Tribes of the northern Willamette Valley practiced a generally settled lifestyle. The Chinooks lived in great wooden lodges , practiced slavery , and had a well-defined caste system. People of the south were more nomadic, traveling from place to place with the seasons. They were known for
7434-510: The PFC. Free trappers Registre Bellaire, John Day and Alexander Carson hunted and traded furs during the winter of 1813-14 along the Willamette. About thirty NWC employees were stationed at the Champoeg post, now called the Willamette Trading Post , along with freemen housed in two huts and Kalapuya nearby. Nez Perce and Cayuse warned the NWC to stay out of the Willamette Valley hunting grounds. Skirmishes went on for several years over fishing and hunting grounds contended by several groups. By
7560-462: The Pacific Ocean. The smaller Multnomah Channel , a distributary , is 21 miles (34 km) long, about 600 feet (180 m) wide, and 40 feet (12 m) deep. It ends about 14.5 miles (23.3 km) farther downstream on the Columbia, near St. Helens in Columbia County . Proposals have been made for deepening the Multnomah Channel to 43 feet (13 m) in conjunction with roughly 103.5 miles (166.6 km) of tandem-maintained navigation on
7686-462: The Sun) rather than internal. Decompression melting happens when solid material from deep beneath the body rises upwards. Pressure decreases as the material rises upwards, and so does the melting point. So, a rock that is solid at a given pressure and temperature can become liquid if the pressure, and thus melting point, decreases even if the temperature stays constant. However, in the case of water, increasing pressure decreases melting point until
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#17327900791877812-413: The Willamette Falls Locks have been inactive. As commerce and industry flourished on the lower river, most of the original settlers acquired farms in the upper Willamette Valley. By the late 1850s, farmers had begun to grow crops on most of the available fertile land. The settlers increasingly encroached on Native American lands. Skirmishes between natives and settlers in the Umpqua and Rogue valleys to
7938-437: The Willamette River was divided into two stretches: the 27-mile (43 km) lower stretch from Portland to Oregon City—which allowed connection with the rest of the Columbia River system—and the upper reach, which encompassed most of the Willamette's length. Any boats whose owners found it absolutely necessary to get past the falls had to be portaged . This led to competition for business among steam portage companies. In 1873,
8064-472: The Willamette Valley especially vulnerable to damage from strong earthquakes. The Willamette River drains a region of 11,478 square miles (29,730 km ), which is 12 percent of the total area of Oregon. Bounded by the Coast Range to the west and the Cascade Range to the east, the river basin is about 180 miles (290 km) long and 100 miles (160 km) wide. Elevations within the watershed range from 10,495 feet (3,199 m) at Mount Jefferson in
8190-434: The Willamette Valley were further divided into groups including the Kalapuyan-speaking Yamhill and Atfalati (Tualatin) (both Northern Kalapuya), Central Kalapuya like the Santiam , Muddy Creek (Chemapho), Long Tom (Chelamela), Calapooia (Tsankupi), Marys River (Chepenafa) and Luckiamute, and the Yoncalla or Southern Kalapuya, as well other tribes such as the Chuchsney-Tufti, Siuslaw and Molala . The name Willamette
8316-435: The Willamette Valley. The total native population was estimated at 15,000. The indigenous peoples of the Willamette River practiced a variety of life ways. Those on the lower river, slightly closer to the coast, often relied on fishing as their primary economic mainstay. Salmon was the most important fish to Willamette River tribes as well as to the Native Americans of the Columbia River, where white traders traded fish with
8442-417: The Willamette Valley. These included the Kalapuya , the Chinook , and the Clackamas . The territory of the Clackamas encompassed the northeastern portion of the basin, including the Clackamas River (with which their name is shared). Although it is unclear exactly when, the territory of the Chinook once extended across the northern part of the watershed, through the Columbia River valley. Indigenous peoples of
8568-423: The Willamette basin. The highest flow recorded at this station was 420,000 cubic feet per second (11,893 m /s) on February 9, 1996, during the Willamette Valley Flood of 1996 , and the minimum was 4,200 cubic feet per second (120 m /s) on July 10, 1978. The highest recorded flow of 635,000 cubic feet per second (18,000 m /s) for the Willamette at a different gauge in Portland occurred during
8694-428: The Willamette ranks 19th in volume among rivers in the United States and contributes 12 to 15 percent of the total flow of the Columbia River. The Willamette's flow varies considerably season to season, averaging about 8,200 cubic feet per second (230 m /s) in August to more than 79,000 cubic feet per second (2,200 m /s) in December. The U.S. Geological Survey (USGS) operates five stream gauges along
8820-404: The Willamette's drainage basin, 13 of which are operated by the U.S. Army Corps of Engineers (USACE). The dams are used primarily to produce hydroelectricity , to maintain reservoirs for recreation, and to prevent flooding. The river and its tributaries support 60 fish species, including many species of salmon and trout ; this is despite the dams, other alterations, and pollution (especially on
8946-419: The Willamette's mouth at the Columbia. Originally created by plate tectonics about 35 million years ago and subsequently altered by volcanism and erosion, the river's drainage basin was significantly modified by the Missoula Floods at the end of the most recent ice age . Humans began living in the watershed over 10,000 years ago. There were once many tribal villages along the lower river and in
9072-447: The Willamette, continued on until the falls portage (present-day Oregon City ) and finished their journey at a flattening of both banks, the later site of Champoeg . A first trading post was established. By early 1813, William Wallace and John C. Halsey established a second outpost, Wallace House , farther south, north of present-day Salem. By the end of the War of 1812 , the NWC acquired
9198-455: The area around its mouth on the Columbia. Indigenous peoples lived throughout the upper reaches of the basin as well. Rich with sediments deposited by flooding and fed by prolific rainfall on the western side of the Cascades, the Willamette Valley is one of the most fertile agricultural regions in North America, and it was thus the destination of many 19th-century pioneers traveling west along
9324-532: The basalt with up to 1,000 feet (300 m) of silt in the Portland and Tualatin basins. During the Pleistocene , beginning roughly 2.5 million years ago, volcanic activity in the Cascades combined with a cool, moist climate to produce further heavy sedimentation across the basin, and braided rivers created alluvial fans spreading down from the east. Between about 15,500 and 13,000 years ago,
9450-691: The basin from the Pacific Ocean. Basalts of the Columbia River Basalt Group , from eruptions primarily in eastern Oregon , flowed across large parts of the northern half of the basin about 15 million years ago. They covered the Tualatin Mountains (West Hills), most of the Tualatin Valley , and the slopes of hills farther south, with up to 1,000 feet (300 m) of lava . Later deposits covered
9576-428: The body's internal heat, but the Moon, which is smaller than Earth, has lost most of this heat. Another heat source is radiogenic heat, caused by radioactive decay . The decay of aluminium-26 would have significantly heated planetary embryos, but due to its short half-life (less than a million years), any traces of it have long since vanished. There are small traces of unstable isotopes in common minerals, and all
9702-406: The body; the heat is generated by various processes, such as radioactive decay or tidal heating . This heat partially melts solid material in the body or turns material into gas. The mobilized material rises through the body's interior and may break through the solid surface. For volcanism to occur, the temperature of the mantle must have risen to about half its melting point. At this point,
9828-492: The city's first officially recognized public swimming beach, Poet's Beach . There are more than 20 major dams on the Willamette's tributaries, as well as a complex series of levees and channels to control the river's flow. The only dam on the Willamette's main stem is the Willamette Falls Dam, a low weir -type structure at Willamette Falls that diverts water into the headraces of the adjacent mills and
9954-414: The city's growing economy. Trade goods from the Columbia basin north of Portland could also be transported southward on the Willamette due to the deeper channels made at the Willamette's mouth. By the early 20th century, major river-control projects had begun to take place. Levees were constructed along the river in most urban areas, and Portland built concrete walls to protect its downtown sector. In
10080-497: The construction of the Willamette Falls Locks bypassed the falls and allowed easy navigation between the upper and lower river. Each lock chamber measured 210 feet (64 m) long and 40 feet (12 m) wide, and the canal was originally operated manually before it switched to electrical power. Usage of the locks peaked in the 1940s, and by the early 21st century, the lock system was little used. Since 2011,
10206-542: The controlled burning of woodlands to create meadows for hunting and plant gathering (especially camas ). The Willamette River first appeared in written records in 1792, when it was observed by British Lieutenant William Robert Broughton of the Vancouver Expedition , led by George Vancouver . The 1805-1806 Lewis and Clark Expedition originally missed the mouth of the Willamette. On their return journey, only after receiving directions from natives along
10332-416: The cryomagma less dense), or with the presence of a densifying agent in the ice shell. Another is to pressurise the fluid to overcome negative buoyancy and make it reach the surface. When the ice shell above a subsurface ocean thickens, it can pressurise the entire ocean (in cryovolcanism, frozen water or brine is less dense than in liquid form). When a reservoir of liquid partially freezes, the remaining liquid
10458-543: The density of impact craters on the surface. Lava flows are widespread and forms of volcanism not present on Earth occur as well. Changes in the planet's atmosphere and observations of lightning have been attributed to ongoing volcanic eruptions, although there is no confirmation of whether or not Venus is still volcanically active. However, radar sounding by the Magellan probe revealed evidence for comparatively recent volcanic activity at Venus's highest volcano Maat Mons , in
10584-532: The difference in height between the basin and the height of the surrounding terrain could allow eruption of magma which otherwise would have stayed beneath the surface. A 2011 article showed that there would be zones of enhanced magma ascent at the margins of an impact basin. Not all of these mechanisms, and maybe even none, operate on a given body . Silicate volcanism occurs where silicate materials are erupted. Silicate lava flows, like those found on Earth, solidify at about 1000 degrees Celsius. A mud volcano
10710-433: The enrichment of magma at the top of a dike by gas which is released when the dike breaches the surface, followed by magma from lower down than did not get enriched with gas. The reason the dissolved gas in the magma separates from it when the magma nears the surface is due to the effects of temperature and pressure on gas solubility . Pressure increases gas solubility, and if a liquid with dissolved gas in it depressurises,
10836-479: The esplanade. The events appear to be unrelated. Public artworks installed along the esplanade include Alluvial Wall , Echo Gate , the Ghost Ship sculpture , the statue of Vera Katz and Stack Stalk . Willamette River The Willamette River ( / w ɪ ˈ l æ m ɪ t / wil- AM -it ) is a major tributary of the Columbia River , accounting for 12 to 15 percent of
10962-447: The following decades, many large dams were built on Cascade Range tributaries of the Willamette. The Army Corps of Engineers operates 13 such dams, which affect flows from about 40 percent of the basin. Most of them do not have fish ladders. With development in and near the river came increased pollution. By the late 1930s, efforts to stem the pollution led to formation of a state sanitary board to oversee modest cleanup efforts. In
11088-427: The form of ash flows near the summit and on the northern flank. However, the interpretation of the flows as ash flows has been questioned. There are several extinct volcanoes on Mars , four of which are vast shield volcanoes far bigger than any on Earth. They include Arsia Mons , Ascraeus Mons , Hecates Tholus , Olympus Mons , and Pavonis Mons . These volcanoes have been extinct for many millions of years, but
11214-475: The founding of the town in 1829. McLoughlin attempted to persuade the HBC (which still held sway over the area) to allow American settlers to live on the land, and provided significant help to American colonization of the area, all against the HBC's orders. Oregon City prospered because of the lumber and grist mills that were run by the water power of Willamette Falls, but the falls formed an impassable barrier to river navigation. Linn City (originally Robins Nest)
11340-605: The gas in the ash as it expands chills the magma fragments, often forming tiny glass shards recognisable as portions of the walls of former liquid bubbles. In more fluid magmas the bubble walls may have time to reform into spherical liquid droplets. The final state of the colloids depends strongly on the ratio of liquid to gas. Gas-poor magmas end up cooling into rocks with small cavities, becoming vesicular lava . Gas-rich magmas cool to form rocks with cavities that nearly touch, with an average density less than that of water, forming pumice . Meanwhile, other material can be accelerated with
11466-432: The gas will tend to exsolve (or separate) from the liquid. An example of this is what happens when a bottle of carbonated drink is quickly opened: when the seal is opened, pressure decreases and bubbles of carbon dioxide gas appear throughout the liquid. Fluid magmas erupt quietly. Any gas that has exsolved from the magma easily escapes even before it reaches the surface. However, in viscous magmas, gases remain trapped in
11592-462: The gas, becoming volcanic bombs . These can travel with so much energy that large ones can create craters when they hit the ground. A colloid of volcanic gas and magma can form as a density current called a pyroclastic flow . This occurs when erupted material falls back to the surface. The colloid is somewhat fluidised by the gas, allowing it to spread. Pyroclastic flows can often climb over obstacles, and devastate human life. Pyroclastic flows are
11718-625: The government to a part of the Coast Reservation that later became the Grande Ronde Reservation . Between 1879 and 1885, the Willamette River was charted by Cleveland S. Rockwell , a topographical engineer and cartographer for the United States Coast and Geodetic Survey . Rockwell surveyed the lower Willamette from the foot of Ross Island through Portland to the Columbia River and then downstream on
11844-657: The largest of these originally weighed about 160 short tons (150 t). The northern part of the watershed is underlain by a network of faults capable of producing earthquakes at any time, and many small quakes have been recorded in the basin since the mid-19th century. In 1993, the Scotts Mills earthquake —the largest recent earthquake in the valley, measuring 5.6 on the Richter scale —was centered near Scotts Mills , about 34 miles (55 km) south of Portland. It caused $ 30 million in damage, including harm to
11970-835: The largest water storage capacity, at 477,700 acre-feet (589,200,000 m ). The other 11 dams are Big Cliff on the North Santiam River; Green Peter and Foster on the Santiam River ; Cougar on the South Fork McKenzie River ; Blue River on the Blue River ; Fern Ridge on the Long Tom River ; Hills Creek and Dexter on the Middle Fork Willamette River; Fall Creek on Fall Creek ; Cottage Grove on
12096-433: The lava rapidly loses viscosity, unlike silicate lavas like those found on Earth. When magma erupts onto a planet's surface, it is termed lava . Viscous lavas form short, stubby glass-rich flows. These usually have a wavy solidified surface texture. More fluid lavas have solidified surface textures that volcanologists classify into four types. Pillow lava forms when a trigger, often lava making contact with water, causes
12222-622: The longest of its kind in the United States. Connected to this is a 120-foot (37 m) public dock. Thirteen markers along the esplanade correspond to the eastside street grid. Construction began in October 1998, and the walkway was dedicated in May 2001. The esplanade was closed for 21 days due to high river levels in 2011, the first time it had been closed since it was built. On the same day in February 2015, two dead bodies were discovered along
12348-426: The magma even after they have exsolved, forming bubbles inside the magma. These bubbles enlarge as the magma nears the surface due to the dropping pressure, and the magma grows substantially. This fact gives volcanoes erupting such material a tendency to ‘explode’, although instead of the pressure increase associated with an explosion, pressure always decreases in a volcanic eruption. Generally, explosive cryovolcanism
12474-421: The mantle's viscosity will have dropped to about 10 Pascal-seconds . When large scale melting occurs, the viscosity rapidly falls to 10 Pascal-seconds or even less, increasing the heat transport rate a million-fold. The occurrence of volcanism is partially due to the fact that melted material tends to be more mobile and less dense than the materials from which they were produced, which can cause it to rise to
12600-664: The next 25 years, some 500,000 settlers traveled the Oregon Trail, to reach the Willamette Valley. Starting in the 1830s, Oregon City developed near Willamette Falls. It was incorporated in 1844, becoming the first city west of the Rocky Mountains to have that distinction. John McLoughlin , the Hudson's Bay Company (HBC) superintendent of the Columbia District , was one of the major contributors to
12726-637: The non-profit Willamette Riverkeeper organization designated the full length of the river as the Willamette River Water Trail. Four years later, the National Park Service added the Willamette water trail—expanded to 217 miles (349 km) to include some of the major tributaries—to its list of National Water Trails . The water trail system is meant to protect and restore waterways in the United States and enhance recreation on and near them. A 1991 agreement between
12852-672: The other terrestrial planets. It has a smooth surface, with mounds, hollows and folds. A volcanic eruption could just be a simple outpouring of material onto the surface of a planet, but they usually involve a complex mixture of solids, liquids and gases which behave in equally complex ways. Some types of explosive eruptions can release energy a quarter that of an equivalent mass of TNT . Volcanic eruptions on Earth have been consistently observed to progress from erupting gas rich material to gas depleted material, although an eruption may alternate between erupting gas rich to gas depleted material and vice versa multiple times. This can be explained by
12978-443: The possibility that the production of pressurised gas upon destabilisation of clathrate hydrates making contact with warm rising magma could produce an explosion that breaks through the surface, resulting in explosive cryovolcanism. If a fracture reaches the surface of an icy body and the column of rising water is exposed to the near-vacuum of the surface of most icy bodies, it will immediately start to boil, because its vapor pressure
13104-509: The pressure of the rock is greater than that of the dike at its bottom. So the magma thus pushes the crack upwards at its top, but the crack is squeezed closed at its bottom due to an elastic reaction (similar to the bulge next to a person sitting down on a springy sofa). Eventually, the tail gets so narrow it nearly pinches off, and no more new magma will rise into the crack. The crack continues to ascend as an independent pod of magma. This model of volcanic eruption posits that magma rises through
13230-479: The raw sewage in the system flowed into the river instead of into the city's wastewater treatment plant. The Big Pipe project and related work reduces CSO volume on the lower river by about 94 percent. In June 2014, Dean Hall became the first person to swim the entire length of the Willamette River. He swam 184 miles (296 km) from Eugene to the river mouth in 25 days. In 2017, Human Access Project partnered with Portland Parks & Recreation to open
13356-540: The river at the Morrison Bridge . The Willamette River basin was created primarily by plate tectonics and volcanism and was altered by erosion and sedimentation, including deposits from enormous glacial floods as recent as 13,000 years ago. The oldest rocks beneath the Willamette Valley are the Siletz River Volcanics . About 35 million years ago, these rocks were subducted by
13482-435: The river in Portland. The 3,700-foot (1,100 m) bridge is the only cantilevered deck truss in Oregon. Volcanism Volcanism , vulcanism , volcanicity , or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a heat source, usually internally generated, inside
13608-579: The river's lower reaches). Part of the Willamette Floodplain was established as a National Natural Landmark in 1987, and the river was named as one of 14 American Heritage Rivers in 1998. The upper tributaries of the Willamette originate in the mountains south and southeast of Eugene, Oregon . Formed by the confluence of the Middle Fork Willamette River and the Coast Fork Willamette River near Springfield ,
13734-470: The river, at Harrisburg, Corvallis, Albany, Salem, and Portland. The average discharge at the lowermost gauge, near the Morrison Bridge in Portland, was 33,220 cubic feet per second (941 m /s) between 1972 and 2013. Located at river mile (RM) 12.8 or river kilometer (RK) 20.6, the gauge measures the flow from an area of 11,200 square miles (29,000 km ), roughly 97 percent of
13860-417: The shallow crust, in cryovolcanism, the water (cryomagmas tend to be water based) is denser than the ice above it. One way to allow cryomagma to reach the surface is to make the water buoyant, by making the water less dense, either through the presence of other compounds that reverse negative buoyancy, or with the addition of exsolved gas bubbles in the cryomagma that were previously dissolved into it (that makes
13986-442: The solar system where volcanoes can be easily seen due to their high activity, Earth and Io. Its lavas are the hottest known anywhere in the Solar System, with temperatures exceeding 1,800 K (1,500 °C). In February 2001, the largest recorded volcanic eruptions in the Solar System occurred on Io. Europa , the smallest of Jupiter's Galilean moons , also appears to have an active volcanic system, except that its volcanic activity
14112-443: The south, settled from this muddy water to form today's valley floor. The floods carried Montana icebergs well into the basin, where they melted and dropped glacial erratics onto the land surface. These rocks, composed of granite and other materials common to central Montana but not to the Willamette Valley, include more than 40 boulders, each at least 3 feet (0.9 m) in diameter. Before being partly chipped away and removed,
14238-583: The southwest of the Willamette River led the Oregon state government to remove the natives by military force. They were first led off their traditional lands to the Willamette Valley, but soon were marched to the Coast Indian Reservation . In 1855, Joel Palmer , an Oregon legislator, negotiated a treaty with the Willamette Valley tribes, who, although unhappy with the treaty, ceded their lands to non-natives. The natives were then relocated by
14364-415: The surface, and the release of pressure causes more gas to exsolve, doing so explosively. The gas may expand at hundreds of metres per second, expanding upward and outward. As the eruption progresses, a chain reaction causes the magma to be ejected at higher and higher speeds. The violently expanding gas disperses and breaks up magma, forming a colloid of gas and magma called volcanic ash . The cooling of
14490-494: The surface. There are multiple ways to generate the heat needed for volcanism. Volcanism on outer solar system moons is powered mainly by tidal heating . Tidal heating caused by the deformation of a body's shape due to mutual gravitational attraction, which generates heat. Earth experiences tidal heating from the Moon , deforming by up to 1 metre (3 feet), but this does not make up a major portion of Earth's total heat . During
14616-424: The swing span was removed in the 1950s. The Oregon City Bridge , built in 1922, replaced a suspension span constructed at the site in 1888. It carries Oregon Route 43 over the river at about RM 26 (RK 42) between Oregon City and West Linn . The Ross Island Bridge carries U.S. Route 26 ( Mount Hood Highway ) over the river at RM 14 (RK 23). It is one of 10 highway bridges crossing
14742-1065: The two major highways that follow the river for its entire length. Communities along the main stem include Springfield and Eugene in Lane County ; Harrisburg in Linn County ; Corvallis in Benton County ; Albany in Linn and Benton counties; Independence in Polk County ; Salem in Marion County ; Newberg in Yamhill County ; Oregon City , West Linn , Milwaukie , and Lake Oswego in Clackamas County ; and Portland in Multnomah and Washington counties. Significant tributaries from source to mouth include
14868-605: The vicinity of the Willamette on a section referred to as French Prairie . By 1841, members of the United States Exploring Expedition came through the Siskiyou Trail. They noted extensive salmon fishing by natives at Willamette Falls, much like that at Celilo Falls on the Columbia River. In the middle part of the 19th century the Willamette Valley's fertile soils, pleasant climate, and abundant water attracted thousands of settlers from
14994-483: The water stored in the reservoirs is used for irrigation . Cougar Dam on the South Fork McKenzie River and Detroit Dam on the North Santiam River are the two tallest dams in the Willamette River basin. Detroit Dam is 463 feet (141 m) high and stores 455,000 acre-feet (561,000,000 m ) of water. Lookout Point Dam on the Middle Fork Willamette River , forming Lookout Point Lake , has
15120-439: The water to exsolve into gas. The elastic nature of the ice shell would likely prevent the fracture reaching the surface, and the crack would instead pinch off, enclosing the gas and liquid. The gas would increase buoyancy and could allow the crack to reach the surface. Even impacts can create conditions that allow for enhanced ascent of magma. An impact may remove the top few kilometres of crust, and pressure differences caused by
15246-459: The water would rise to its level of hydrostatic equilibrium, at about nine-tenths of the way to the surface. Tides which induce compression and tension in the ice shell may pump the water farther up. A 1988 article proposed a possibility for fractures propagating upwards from the subsurface ocean of Jupiter's moon Europa. It proposed that a fracture propagating upwards would possess a low pressure zone at its tip, allowing volatiles dissolved within
15372-678: The watershed. In 1987, the U.S. Secretary of the Interior designated 713 acres (289 ha) of the watershed in Benton County as a National Natural Landmark . This area is the Willamette Floodplain , the largest remaining unplowed native grassland in the North Pacific geologic province, which encompasses most of the Pacific Northwest coast. For at least 10,000 years, a variety of indigenous peoples populated
15498-439: The winter of 1818-19, Thomas McKay led a hunting brigade farther south towards the sources of the Willamette River and reached the upper Umpqua River . More violent skirmishes were fought. Most brigade members returned to Fort George (formerly called Fort Astoria ). Louis LaBonté, Joseph Gervais , Étienne Lucier , Louis Kanota, and Louis Pichette (dit DuPré) remained in the Willamette Valley as free trappers. Meanwhile, in 1821
15624-402: Was established across the Willamette from Oregon City. After Portland was incorporated in 1851, quickly growing into Oregon's largest city, Oregon City gradually lost its importance as the economic and political center of the Willamette Valley. Beginning in the 1850s, steamboats began to ply the Willamette, despite the fact that they could not pass Willamette Falls. As a result, navigation on
15750-701: Was renamed for former Portland mayor Vera Katz in November 2004 and features a statue of her near the Hawthorne Bridge . The project, designed by landscape architects Mayer/Reed, cost $ 30 million, of which $ 10 million built a lower deck on the Steel Bridge . The esplanade extends 1.5 miles (2.4 km) from the Steel Bridge ( 45°31′37″N 122°40′13″W / 45.526871°N 122.670403°W / 45.526871; -122.670403 ( Esplanade north end at Steel Bridge ) ) to
15876-545: Was used to reach farther south. This trail, over 600 miles (970 km) long, stretched from the mouth of the Willamette River near present-day Portland south through the Willamette Valley, crossing the Siskiyou Mountains , and south through the Sacramento Valley to San Francisco . In 1812, William Henry and Alfred Seton paddled up from Fort Astoria (PFC) on the Columbia River into the mouth of
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