140-714: The Olympic–Wallowa lineament (OWL) is a series of geologic structures oriented from northwest to southeast for 650 km (400 mi) across Washington and northeast Oregon in the United States, passing through the Seattle area and including notable features east of the Cascade Range such as the Yakima Fold Belt and Wallowa Mountains . It was first reported by cartographer Erwin Raisz in 1945 on
280-635: A temperate rainforest . Weeks may pass without a clear day. The western slopes of the Cascade Range receive some of the heaviest annual snowfall (in some places more than 200 inches or 5,100 millimeters water equivalent) in the country. In the rain shadow area east of the Cascades, the annual precipitation is only 6 inches (150 mm). Precipitation then increases again eastward toward the Rocky Mountains (about 120 miles (190 km) east of
420-447: A Puget Sound Fault. (Such a fault was once proposed on the basis of certain marine seismic data, but the proposal was stiffly rejected, and now seems to have been abandoned.) Combined terrestrial and bathymetric topography shows a distinct lineament along the west side of Puget Sound from Vashon Island (just north of Tacoma) north to the west side of Holmes Harbor and Saratoga Passage on Whidbey Island (see image). But at Port Madison (at
560-447: A broad zone of more regular alignments. Subsequent geological investigations have suggested various refinements and adjustments. Most geological features are initially identified or characterized from a local expression of that feature. The OWL was first identified as a perceptual effect, a pattern perceived by the human visual system in a broad field of many seemingly random elements. But is it real? Or just an optical illusion , such as
700-670: A feature begins with determining its structure, composition, age, and relationship with other features. The OWL does not cooperate. It is expressed as an orientation in many elements of diverse structure and compositions, and even as a boundary between areas of differing structure and composition; there is yet no understanding of what kind of feature or process – the "ur-OWL" – could control this. Nor are there particular "OWL" rocks which can be examined and radiometrically dated. We are left with determining its age by looking at its relationship with other features, such as which features overlap or cross-cut other (presumably older) features. In
840-477: A large part of the top of the volcano. The eruption flattened the forest up to 20 km north of the volcano , killed 57 people, flooded the Columbia River and its tributaries with ash and mud, and blanketed large parts of Washington eastward and other surrounding states in ash, making day look like night. Washington is the northwesternmost state of the contiguous United States . It borders Idaho to
980-645: A large region experiences strong rain shadow effects. Semi-arid conditions occur in much of Eastern Washington with the strongest rain shadow effects at the relatively low elevations of the central Columbia Plateau —especially the region just east of the Columbia River from about the Snake River to the Okanagan Highland . Thus, instead of rain forests, much of Eastern Washington is covered with dry grassland , shrub-steppe , and dunes . The average annual temperature ranges from 51 °F (11 °C) on
1120-425: A low-pressure cyclone system takes over in the north Pacific Ocean. The air spiraling inward in a counter-clockwise fashion causes Washington's prevailing winds to come from the southwest, and bring cool and overcast weather and a predictably wet season . The term " Pineapple Express " is used colloquially to describe atmospheric river events, where repeated storm systems are directed by this persistent cyclone from
1260-661: A pivot somewhere in the Olympic Peninsula (see Oregon rotation , below). This would have left a large gap south of the OWL, which could explain why Cenozoic rocks are not found immediately south of the OWL. This suggests that a continuation of the SCF, if any, and the missing Cenozoic, might be somewhere southwest of Mount St. Helens , but this has not been observed. The interaction of the Straight Creek Fault with
1400-612: A point in Washington State. The rotational geologic pole for right-lateral faults and seismicity lineations in western Washington and Oregon is 47°54′N 117°42′W / 47.9°N 117.7°W / 47.9; -117.7 Measurements of paleomagnetism (the record of the direction the rock was pointed when it cooled) from a variety of sites in the Coast Range – from the Klamath Mountains to
1540-461: A preliminary assessment of the risks and opportunities presented given the possibility of a rise in global temperatures and their effects on Washington state. Rainfall in Washington varies dramatically going from east to west. The Olympic Peninsula's western side receives as much as 160 inches (4,100 mm) of precipitation annually, making it the wettest area of the 48 conterminous states and
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#17327762336391680-474: A proposal to use the name "State of Washington, Douglass Commonwealth", which would conflict with the current state of Washington. Residents of Washington (known as "Washingtonians") and the Pacific Northwest simply refer to the state as "Washington", and the nation's capital "Washington, D.C.", "the other Washington", or simply "D.C." The 9,300-year-old skeletal remains of Kennewick Man , one of
1820-497: A relief map of the continental United States. Some geologists have questioned the existence of a geological relationship between the individual structures along the lineament suggesting it is an optical illusion. The origin of this feature in its entirety is not well understood with multiple hypotheses on the subject. The Olympic–Wallowa lineament likely predates the Columbia River Basalt Group . Raisz located
1960-469: A rise in the crustal basement beneath the OWL, but was unable to determine if that rise was aligned with the OWL, or just coincidentally crossed the OWL at the same location as the profile; gravity data suggested the latter. The seismic data showed a uniformity of rock type and thickness across the OWL that discounts the possibility of it being a boundary between continental and oceanic crust. The results were interpreted as suggesting continental rifting during
2100-514: A sill would exist. Washington (state) Washington , officially the State of Washington , is a state in the Pacific Northwest region of the United States. It is often referred to as Washington state to distinguish it from the national capital , both named after George Washington (the first U.S. president ). Washington borders the Pacific Ocean to the west, Oregon to
2240-514: A state; the creation of Idaho Territory in 1863 established the final eastern border. A Washington state constitution was drafted and ratified in 1878, but it was never officially adopted. Although never approved by the United States Congress, the 1878 constitution is an important historical document that shows the political thinking of the time; it was used extensively during the drafting of Washington state's 1889 constitution,
2380-543: A three-man commission ruling in favor of the United States in 1872. The border established by the Oregon Treaty and finalized by the arbitration in 1872 remains the boundary between Washington and British Columbia . The growing population of Oregon Territory north of the Columbia River formally requested a new territory. As a result of the Monticello Convention , held in present-day Cowlitz County ,
2520-439: A varied range of bird species. This range includes raptors, shorebirds, woodland birds, grassland birds, ducks, and others. There have also been a large number of species introduced to Washington, dating back to the early 18th century, including horses and burros. The channel catfish , lamprey , and sturgeon are among the 400 known freshwater fishes . Along with the Cascades frog, there are several forms of snakes that define
2660-590: A zone about 50 km wide on the Oregon coast the apparent rotation rate seems to double; this suggests that multiple models may be applicable. Modern measurements show that central Oregon is still rotating, with the calculated rotation poles bracketing the Wallula Gap, which is approximately the intersection of the OWL and KBML. It is intriguing to consider whether the KBML has participated in this rotation, but this
2800-411: Is a major fault notable for considerable identified dextral strike-slip offset (opposite side moving laterally to the right) of at least 90 km (56 mi). Its intersection with the OWL (near Kachess Lake ) is the geological equivalent of an atom smasher, and the results should be informative. For example, that the OWL is not offset suggests that it must be younger than the last strike-slip motion on
2940-497: Is a region of grabens (where large blocks of crust have dropped) extending about 60 miles (97 km) south to the nearly parallel Vale Fault Zone (see diagram, below). Grabens form where the crust is being stretched or extended. Several explanations have been offered as to why this is happening here. Kuehn (1995) theorized that right-lateral slip on the Wallula Fault is being transferred to more southerly faults such as
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#17327762336393080-486: Is a result of regional stresses, and is expressed only in the superficial basalt, quite independently of what ever is happening in the basement rock. At the western edge of the Blue Mountains the Wallula Fault zone intersects the northeast-striking Hite Fault System (HFS). This system is complex and has been variously interpreted. Although seismically active it appears to be offset by, and thus should be older than,
3220-652: Is also found in the San Juan Islands, and along the West Coast fault on the west side of Vancouver Island. This suggests that the OWL was once a strike-slip fault, possibly a continental margin, along which terranes moved from the southeast. But similar rock also occurs in the Rimrock Lake Inlier, about 75 km south of the OWL and just west of the projected trace of the SCF, and also in the Klamath Mountains of southwestern Oregon. To account for
3360-490: Is an extremely important business throughout much of Eastern Washington, as the soil is highly productive and irrigation , aided by dams along the Columbia River, is fairly widespread. The spread of population in Eastern Washington is dominated by access to water, especially rivers. The main cities are all located alongside rivers or lakes; most of them are named after the river or lake they adjoin. Farther east,
3500-426: Is as yet no understanding of what the OWL is or how it came to be. The OWL piques the interest of geologically minded persons in part because its characteristic NW-SE angle of orientation – approximately 50 to 60 degrees west of north (a little short of northwest) – is shared by many other seeming local features across a broad swath of geography. Around Seattle these include strikingly parallel alignments at
3640-624: Is just when the Kula–;Farallon spreading ridge passed under the OWL (discussed below ). Magill & Cox (1981) found a spurt of rapid rotation around 45 Ma ago. This may be when this block was impinged by the Sierra Nevada block of California; Simpson & Cox (1977) note that around 40 Ma ago there was a change in the direction of the Pacific Plate (possibly due to collision with another plate). (The cause and nature of
3780-468: Is more nearly in line with the rest of the OWL, and in line with the previously mentioned gravitational anomalies that run into the continent. Which ever way is deemed correct, it is notable that the OWL seems to change character after it crosses the Hite Fault System. What this says about the nature of the OWL is unclear, although Kuehn concluded that, in northeastern Oregon or western Idaho, it
3920-408: Is not a strike-slip fault, but a thrust fault , where a relatively shallow slab of rock from the south is being pushed against and over the northern part. (And over the OWL.) One model has the slab of rock being forced up by some structure about 8 km deep. Another model has the base of the slab (again, about 8 km deep) catching on something, which causes the leading edge to roll. The nature of
4060-601: Is not a tectonically significant structure. As described above, the trace of the OWL becomes faint and somewhat confused between the Blue Mountains and the margin of the North American craton (the thick orange line on the map , just beyond the Oregon—;Idaho border; the dashed line on the diagram below). This is the Wallowa terrane, a piece of crust that drifted in from somewhere else and got jammed between
4200-515: Is not the inconsistency it may initially seem – think of the motion on either side of an arrowhead. It appears that what is now the DDMFZ was originally aligned on the OWL. Then about 50 Ma ago North America crashed into what is now the Olympic Peninsula along an axis nearly perpendicular to the OWL, pushing the rock of the Mesozoic (pre-Cenozoic) Western and Eastern Melange Belts (WEMB, blue on
4340-414: Is possibly explained as a geometrical effect of foreshortening: it occurs in a belt of intense folding (much resembling a rug which has slid against a wall) which, if unfolded, could restore some of the "curves" to a linear position along the southerly extension of the SCF. There seem to be no indications that the SCF turns to the west. Although such indications would mostly be buried, the general sense of
Olympic–Wallowa lineament - Misplaced Pages Continue
4480-403: Is similarly suggestive of ripples in a flow that is obliquely crossing some deeper sill. This is an intriguing idea that could explain how local and seemingly independent features could be organized from depth, and even across a large scale, but it does not seem to have been considered. This is likely due, in part, to a paucity of information on the nature and structure of the lower crust where such
4620-477: Is southwestern Washington and Oregon, which has virtually no pre-Cenozoic strata. This is the Columbia Embayment, a large indentation into the North American continent characterized by oceanic crust covered by thick sedimentary deposits. ("Embayment" is perhaps a misleading term, in that it suggests a bowing of a coast line, which only seems so in the context of the modern coast. In the geological past,
4760-405: Is the only U.S. state named after a president. Confusion between the state of Washington and the city of Washington, D.C., led to renaming proposals during the statehood process for Washington in 1889, including David Dudley Field II 's suggestion to name the new state "Tacoma"; these proposals failed to garner support. Washington, D.C.'s, own statehood movement in the 21st century has included
4900-564: Is the second most populous state on the West Coast and in the Western United States, after California . Mount Rainier , an active stratovolcano , is the state's highest elevation at 14,411 feet (4,392 meters), and is the most topographically prominent mountain in the contiguous U.S. Washington is a leading lumber producer, the largest producer of apples, hops, pears, blueberries, spearmint oil, and sweet cherries in
5040-408: Is unclear; that it is unbent where it crosses the OWL suggests it is not. The OWL seems to be the northern edge of the rotating block, and the paucity of paleomagnetic data to the southeast of the KBML suggests it might be the southern edge. But the details of all this remain murky. Another notable feature that crosses the OWL is Puget Sound , and it is curious to consider the possible implications of
5180-506: The Blue Mountains and the eastern sides of the Cascades. Mammals native to the state include the bat , black bear , bobcat , cougar , coyote , deer , elk , gray wolf , hare , moose , mountain beaver , muskrat , opossum , pocket gopher , rabbit , raccoon , river otter , skunk , and tree squirrel . Because of the wide range of geography, the state of Washington is home to several different ecoregions, which allow for
5320-435: The Blue Mountains . The state of Washington has a temperate climate. The eastern half of Washington has a semi-arid to warm-summer mediterranean climate , while the western side of Washington as well as the coastal areas of the state have a cool oceanic climate or warm-summer mediterranean climate. Major factors determining Washington's climate include the large semi-permanent low pressure and high pressure systems of
5460-482: The Canadian province of British Columbia to the north. Washington is part of a region known as the Pacific Northwest , a term which always refers to at least Washington and Oregon, and may or may not include some or all the following, depending on the user's intent: Idaho, western Montana , northern California , British Columbia, and Alaska . The high mountains of the Cascade Range run north-south, bisecting
5600-567: The Cascade Mountains westward, Western Washington has a mostly Mediterranean climate , with mild temperatures and wet winters, autumns and springs, and relatively dry summers. The Cascade Range has several volcanoes , which reach altitudes significantly higher than the rest of the mountains. From north to south, these major volcanoes are Mount Baker , Glacier Peak , Mount Rainier , Mount St. Helens , and Mount Adams . All are active volcanoes. Mount Rainier—the tallest mountain in
5740-707: The Columbia District . Fur trapper James Sinclair , on orders from Sir George Simpson , Governor of the Hudson's Bay Company, led some 200 settlers from the Red River Colony west in 1841 to settle on Hudson Bay Company farms near Fort Vancouver . The party crossed the Rockies into the Columbia Valley , near present-day Radium Hot Springs , British Columbia, then traveled south-west down
Olympic–Wallowa lineament - Misplaced Pages Continue
5880-815: The Continental Divide to the Pacific Ocean as part of the Anglo–American Convention of 1818 , which established the 49th parallel as the international boundary west from Lake of the Woods to the Rocky Mountains . Resolution of the territorial and treaty issues west to the Pacific was deferred until a later time. In 1819, Spain ceded its rights north of the 42nd parallel to the United States. Negotiations with Great Britain over
6020-922: The Garlock Fault , a major left lateral, or sinistral, strike-slip fault . The north-northwest end of the Walker Lane is between Pyramid Lake in Nevada and California's Lassen Peak where the Honey Lake Fault Zone , the Warm Springs Valley Fault, and the Pyramid Lake Fault Zone meet the transverse tectonic zone forming the southern boundary of the Modoc Plateau and Columbia Plateau provinces. The Walker Lane takes up 15 to 25 percent of
6160-652: The Hanford Reservation ) show no indication of any fault or other structure comparable to the SCF. On the other hand, Cheney (1999) maps the SCF as proceeding southerly (without addressing the situation south of the OWL). (He has subsequently speculated that the missing part of the SCF may have been dextrally offset to become a southerly trending fault in the Puget Lowland. But same problem: later deposits cover any traces.) The seeming southeasterly curvature
6300-656: The Kanizsa triangle (see image), where we "see" a triangle that does not really exist? Raisz considered whether the OWL might be just a chance alignment of random elements, and geologists since have not been able to find any common unitary feature, nor identify any connection between the various local elements. Davis (1977) called it a "fictional structural element". Yet it has been found to coincide with many faults and fault zones, and to delineate significant differences of geology. These are much too correlated to be dismissed as random alignments. But for all of its prominence, there
6440-542: The Kootenai River and Columbia River. Despite such efforts, Britain eventually ceded all claims to land south of the 49th parallel to the United States in the Oregon Treaty on June 15, 1846. In 1836, a group of missionaries, including Marcus Whitman , established several missions and Whitman's own settlement Waiilatpu, in what is now southeastern Washington state, near present-day Walla Walla County , in
6580-603: The San Juan Islands is heavily inhabited by killer , gray, and humpback whales. In Eastern Washington, the flora is vastly different. Tumbleweeds and sagebrush dominate the landscape throughout large parts of the countryside. Russian olives and other trees are common alongside riverbanks; however, apart from the riversides, large swaths of Eastern Washington have no naturally existing trees at all (though many trees have been planted and are irrigated by people, of course). A wider variety of flora can be found in both
6720-825: The Santiago , part of a two-ship flotilla with the Sonora . He claimed the coastal lands up to Prince William Sound for Spain as part of their claimed rights under the Treaty of Tordesillas , which they maintained made the Pacific a "Spanish lake" and all its shores part of the Spanish Empire. Soon thereafter, the smallpox epidemic of the 1770s devastated the Native American population. In 1778, British explorer Captain James Cook sighted Cape Flattery , at
6860-473: The Seattle metropolitan area , the center of transportation, business, and industry on Puget Sound , an inlet of the Pacific Ocean consisting of numerous islands, deep fjords and bays carved out by glaciers. The remainder of the state consists of deep temperate rainforests in the west; mountain ranges in the west, center, northeast, and far southeast; and a semi-arid basin region in the east, center, and south, given over to intensive agriculture. Washington
7000-541: The Sierra Nevada–Great Valley Block and North America . The belt is characterized by the northwest-striking trans-current faults and co-evolutionary dip-slip faults formed as result of a spatially segregated displacement field. The eastern California shear zone is the portion of the Walker Lane that extends south from Owens Valley , and continues across and south of the Garlock Fault, across
7140-470: The U.S. Congress passed legislation to create Washington Territory . It was signed into law by President Millard Fillmore on March 2, 1853. The boundary of Washington Territory initially extended farther east than the present state, including what is now the Idaho Panhandle and parts of western Montana, and picked up more land to the southeast that was left behind when Oregon was admitted as
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#17327762336397280-623: The United States Congress during the creation of Washington Territory in 1853; the territory was to be named "Columbia", for the Columbia River and the Columbia District , but Kentucky representative Richard H. Stanton found the name too similar to the District of Columbia (the national capital, itself containing the city of Washington), and proposed naming the new territory after President Washington. Washington
7420-724: The Walker Lane lineament in Nevada. Likewise to the east, where both the OWL and the Brothers Fault Zone become less distinct in Idaho where they hit the old North American continental craton and the track of Yellowstone hotspot . But some 50 miles to the north is the parallel Trans-Idaho Discontinuity, and further north, the Osburn fault (Lewis and Clark line) running roughly from Missoula to Spokane. And aeromagnetic and gravitational anomaly surveys suggest extension into
7560-447: The basement rock , these faults are somewhat isolated from the deeper structure. The geological consensus is that any strike-slip activity on the OWL predates the 17 Ma old Columbia River Basalt Group . There is some evidence that some of the northwest-trending ridges may have some continuity with the basement structure, but the nature and details of the deeper structure is not known. A 260 km long seismic refraction profile showed
7700-585: The "deep freeze" winters of 1883–1884, 1915–1916, 1949–1950, and 1955–1956, among others. During these events, Western Washington experienced up to 6 feet (1.8 m) of snow, sub-zero (−18 °C) temperatures, three months with snow on the ground, and lakes and rivers frozen over for weeks. Seattle's lowest officially recorded temperature is 0 °F (−18 °C) set on January 31, 1950, but low-altitude areas approximately three hours away from Seattle have recorded lows as cold as −48 °F (−44 °C). The Southern Oscillation greatly influences weather during
7840-419: The Blue Mountains away from the OWL; this might also explain why the OWL seems to be bending here. These theories may all have some truth to them, but what they might imply regarding the genesis and structure of the OWL has not been worked out. Hells Canyon – North America's deepest river gorge – is so deep because the terrain it cuts through is so high. This is generally attributed to thinning of
7980-476: The Columbia Embayment to the west and the North American continent to the east and north. A notable feature is the anomalously elevated Wallowa Mountains , to the east is Hells Canyon (Snake River) on the Oregon—Idaho border. Northeast of the OWL (Wallowa Mountains) is the Clearwater Embayment ("CE" on the map ), delineated by ancient rock of the craton. Southwest of this section of the OWL
8120-399: The Columbia River just north of the Oregon border). This segment, and the associated Yakima fold belts , do include many northeast-trending faults crossing the OWL. However, these are largely dip-slip (vertical) faults, associated with compressional folding of the overlying basalt. As there is typically 3 km of sedimentary deposits separating the basalts (also about 3 km thick) from
8260-756: The Eastside) the Northrup Valley (Hwy. 520 from Yarrow Bay to the Overlake area), and various smaller details too numerous to mention. All of these are carved into "recent" (less than 18,000 years old) glacial deposits, and it is difficult to conceive of how these could be controlled by anything other than a recent glacial process. Yet the same orientation shows up in the Brothers, Eugene-Denio, and McLoughlin fault zones in Oregon (see map , below), which are geological features tens of millions of years old, and
8400-640: The Eocene, perhaps a failed rift basin , possibly connected with the rotation of the Klamath Mountain block away from the Idaho Batholith (see Oregon rotation , below). There is a curious change of character of the OWL in the center of the CLEW where it crosses the roughly north-trending Hog Ranch—Naneum Anticline. West of there the OWL seems to follow a ridge in the basement structure, to
8540-554: The Hite Fault System is not associated with any major fault systems. But mapping of gravitational anomalies shows a definite lineament, some 700 km (about 400 miles) long, called the Klamath-Blue Mountain Lineament (KBML). This lineament is of interest here because of the possibility it was formerly conjugate with OWL, discussed in the next section. Rotation of the Earth's crust around the U.S. state of Oregon has been inferred from geodesy , paleomagnetism and other measurements. The Oregon Coast Range fault block rotates around
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#17327762336398680-496: The Idaho border). The Olympic mountains and Cascades compound this climatic pattern by causing orographic lift of the air masses blown inland from the Pacific Ocean, resulting in the windward side of the mountains receiving high levels of precipitation and the leeward side receiving low levels. This occurs most dramatically around the Olympic Mountains and the Cascade Range. In both cases, the windward slopes facing southwest receive high precipitation and mild, cool temperatures. While
8820-440: The Interior had a different subsistence-based culture based on hunting, food-gathering and some forms of agriculture, as well as a dependency on salmon from the Columbia and its tributaries. The area has been known to host megathrust earthquakes in the past, the last being the Cascadia earthquake of 1700 . The first recorded European landing on the Washington coast was by Spanish Captain Don Bruno de Heceta in 1775, on board
8960-401: The Kittitas Valley (I-90), Manastash Ridge , the Wallula Gap (on the Columbia River where it approaches the Oregon state line), and then the South Fork of the Walla Walla River into the northeastern corner of Oregon. After crossing the Blue Mountains Riasz associated the OWL with a dramatic scarp on the north side of the Wallowa Mountains . Riasz observed that the OWL tends to have basins on
9100-419: The Northwest Coast to explorers and traders from other nations, most notably Britain and Russia as well as the fledgling United States. American captain Robert Gray (for whom Grays Harbor County is named) then discovered the mouth of the Columbia River. He named the river after his ship, the Columbia . Beginning in 1792, Gray established trade in sea otter pelts. The Lewis and Clark Expedition entered
9240-402: The OWL has yielded practically no intelligible information, and remains as enigmatic as the OWL itself. More informative is the closely related Darrington—Devils Mountain Fault Zone (DDMFZ). It runs east from a complex of faults on the southern end of Vancouver Island to the town of Darrington, where it turns south to converge with the SCF (see map, above). North of the DDMFZ (and west of
9380-430: The OWL might reflect a deeper crustal boundary has been questioned by geophysical studies which may – or may not – see the characteristics expected of such a boundary. The southern edge of the Columbia Embayment is along a line from the Klamath Mountains on the Oregon coast to a point in the Blue Mountains just east of the Wallula Gap. Unlike the OWL, this line has little topographical expression, and aside from
9520-407: The OWL particularly from Cape Flattery (the northwest corner of the Olympic Peninsula) and along the north shore of Lake Crescent, thence the Little River (south of Port Angeles ), Liberty Bay (Poulsbo), Elliott Bay (setting the orientation of the streets in downtown Seattle), the north shore of Mercer Island, the Cedar River (Chester Morse Reservoir), Stampede Pass (Cascade crest), the south side of
9660-437: The OWL's context, and even constrain possible models. Likewise, clarification of the nature and history of the Wallowa terrane, and particularly of the nature and causes of the apparent bending and multiple alignments of the OWL in this region, would be a major step in understanding the OWL. The bedrock of Washington and Oregon, like most of the continent, is nearly all pre-Cenozoic rock, older than 66 million years. The exception
9800-412: The OWL, just east of the SCF. This can explain an early puzzle as to why the Mesozoic rocks just south of the DDMFZ – the Western and Eastern Melange Belts – have no counterpart on the east side of the OWL and offset to the south: they were not faulted by the SCF, but were pushed against it from the southwest. Then it gets curiouser. Rock very similar to the WEMB (including a type called blueschist )
9940-432: The OWL, the material of the South Cascades being Cenozoic (<66 Ma ) volcanic and sedimentary rock, and the North Cascades being much older Paleozoic (hundreds of millions of years) metamorphic and plutonic rocks. It is unknown whether this difference is in any way linked with the OWL, or is simply a coincidental regional difference. Raisz judged the Cascades on the north side of the OWL to be offset about six miles to
10080-473: The OWL. Hammond (1979) argues that the Coast Range (believed to be seamounts that had previously accreted to the continent) were rifted away from the continent starting about 50 Ma ago (mid- Eocene ). This interpretation implies a " back arc " of magmatism, probably fed by a subduction zone, and possibly implicated with the intrusion of various plutons in the North Cascades around 50 Ma. Curiously, this
10220-426: The OWL. This is suggestive of the OWL being a left lateral (sinistral) strike-slip fault that has distorted and offset the SCF. But that is inconsistent with the SCF itself and most other strike-slip faults associated with the OWL being right lateral (dextral), and incompatible with the geology to the southeast. Particularly, studies of the region to the southeast (in connection with Department of Energy activities at
10360-413: The Olympic Peninsula – consistently measure clockwise rotations of 50 to 70 degrees. (See map, below.) One interpretation of this is that western Oregon and southwestern Washington have swung as a rigid block about a pivot point at the northern end, near the Olympic Peninsula. The interesting thing is: backing out this rotation restores the Coast Range to an earlier position nearly juxtaposed against
10500-801: The Oregon Trail, wandered north to settle in the Puget Sound area. Spanish and Russian claims to the region were ceded in the early 19th century through a series of treaties. The Spanish signed the Adams–Onís Treaty of 1819, and the Russians the Russo-American Treaty of 1824 and 1825 . The Oregon Question remained contested between the United Kingdom and the United States until the 1846 Oregon Treaty established
10640-486: The Pacific coast to 40 °F (4 °C) in the northeast. The lowest temperature recorded in the state was −48 °F (−44 °C) in Winthrop and Mazama . The highest recorded temperature in the state was 120 °F (49 °C) at Hanford on June 29, 2021. Both records were set east of the Cascades. Western Washington is known for its mild climate, considerable fog, frequent cloud cover, long-lasting drizzles in
10780-411: The Puget Sound lowlands are known for clouds and rain in the winter, the western slopes of the Cascades receive larger amounts of precipitation, often falling as snow at higher elevations. Mount Baker , near the state's northern border, is one of the snowiest places in the world. In 1999, it set the world record for snowfall in a single season—1,140 inches (95 ft; 29 m). East of the Cascades,
10920-478: The SCF (about 40 Ma ago) was dominantly dip-slip (vertical displacement). So perhaps the displacement came from the depths, and, as it was extruded, was eroded and redistributed as sediments. But this has not been established. Another possibility is that the missing southern segment of the SCF is on a crustal block that rotated away from the OWL. There is evidence that around 45 million years ago much of Oregon and southwestern Washington rotated some 60° or more about
11060-435: The SCF anywhere south of the OWL. While some geologists have speculated that it does continue directly south, albeit hidden under younger deposits, not a trace has been found. If the SCF fault does not continue directly southward – and the utter lack of evidence that it does makes a case for evidence of lack – then where else might it be? Heller, Tabor & Suczek (1987) suggest some possibilities: it may curve to
11200-591: The SCF) is the Chuckanut Formation (part of the "Northwest Cascade System" of rocks shown in green on the map), an Eocene sedimentary formation which formed adjacent to the Swauk, Roslyn and other formations (also in green) south of Mount Stuart ; their wide separation is attributed to right-lateral strike-slip movement along the SCF. That the northern part of the DDMFZ shows left -lateral strike-slip movement
11340-411: The SCF, anywhere from around 44 to about 41 million years ago (i.e., during the middle- Eocene epoch). And if the OWL is a strike-slip fault or megashear, as many have speculated, then it should offset the SCF, and whether the OWL offsets the SCF, or not, becomes an important test of just what the OWL is. So does the OWL offset the SCF, or not? It is hard to say, as no trace whatsoever has been found of
11480-536: The Ship Canal, aligned with the red line) – but for this there is even less evidence than there was for the Puget Sound fault. The significance of this lineament and its offset is entirely unknown. That it seems to be expressed in Ice Age (16 Ka) deposits implies a very recent but entirely unknown event; but perhaps these recent deposits are only draped over a much older topography. A recent offset might explain
11620-561: The U.S., and ranks high in the production of apricots, asparagus, dry edible peas, grapes, lentils, peppermint oil, and potatoes. Livestock, livestock products, and commercial fishing—particularly of salmon, halibut, and bottomfish —are also significant contributors to the state's economy. Washington ranks second only to California in wine production. Manufacturing industries in Washington include aircraft, missiles, shipbuilding, and other transportation equipment, food processing, metals, and metal products, chemicals, and machinery. The state
11760-586: The Vale Fault, wherefore he labelled this region the Wallula–;Vale Transfer Zone. Essman (2003) suggested that crustal deformation in this region is a continuation of the Basin and Range region immediately to the south, with any connection to the OWL deemed circumstantial. Another explanation is that clock-wise rotation of part of Oregon (discussed below) about a point near the Wallula Gap has pulled
11900-516: The Wallula and Hite Fault systems is not yet understood. Past the Hite Fault System the OWL enters a region of geological complexity and confusion, where even the trace of the OWL is less clear, even to the point where it has been suggested that both the topographic feature and the Wallula fault are terminated by the Hite fault. The original topographic lineament as described by Raisz is along the scarp on
12040-518: The Wallula fault. On the other hand, a later study found "no obvious displacement" of either the OWL or HFS–related faults. Reidel et al. suggested that the HFS reflects the eastern margin of a piece of old continental craton (centered around the "HF" – Hite Fault – on the map ) that has slipped south; Kuehn attributed 80 to 100 kilometers of left-lateral displacement along the HFS (and significant vertical displacements). The interaction of
12180-403: The apparent offsetting of north–south glacial drumlins bisected by the Ship Canal, but is not evident in more eastern segments. Alternately – and this would seem very pertinent in regard of the OWL – perhaps some mechanism other than strike-slip faulting creates these lineaments. A locally notable feature that crosses the zone of the OWL is the west–east Seattle Fault . This
12320-514: The border between British North America and the United States along the 49th parallel until the Strait of Georgia . Vague wording in the treaty left the ownership of the San Juan Islands in doubt; during the so-called Pig War , both nations agreed to a joint military occupation of the islands. Kaiser Wilhelm I of the German Empire was selected as an arbitrator to end the dispute, with
12460-656: The boundary motion between the Pacific plate and the North American plate , the other 75 percent being taken up by the San Andreas Fault system to the west. The Walker Lane may represent an incipient major transform fault zone which could replace the San Andreas as the plate boundary in the future. The Walker Lane deformation belt also accommodates nearly 12 mm/yr of dextral shear between
12600-523: The climate becomes less arid, with annual rainfall increasing as one goes east to 21.2 inches (540 mm) in Pullman, near the Washington–Idaho border. The Okanogan Highlands and the rugged Kettle River Range and Selkirk Mountains cover much of the state's northeastern quadrant. The Palouse southeast region of Washington was grassland that has been mostly converted into farmland, and extends to
12740-584: The coast of North America was in Idaho and Nevada, as will be described later.) The Columbia Embayment is of interest here because its northern margin is approximately delineated by the OWL. The variations are mainly in the region of the CLEW , where sediments are buried under the basalts of the Columbia Basin , and in Puget Sound, where the Cenozoic geology extends as far north as Vancouver Island. Whether
12880-708: The cold season. During the El Niño phase, the jet stream enters the U.S. farther south through California, therefore late fall and winter are drier than normal with less snowpack. The La Niña phase reinforces the jet stream through the Pacific Northwest, causing Washington to have more rain and snow than average. In 2006, the Climate Impacts Group at the University of Washington published The Impacts of Climate change in Washington's Economy ,
13020-716: The contiguous 48 states. Western Washington also is home of the Olympic Mountains , far west on the Olympic Peninsula , which support dense forests of conifers and areas of temperate rainforest . These deep forests, such as the Hoh Rainforest , are among the only rainforests in the continental United States. While Western Washington does not always experience a high amount of rainfall as measured in total inches of rain per year, it does consistently have more rainy days per year than most other places in
13160-529: The country. Eastern Washington —the part of the state east of the Cascades—has a relatively dry climate, in distinct contrast to the west side. It includes large areas of semiarid steppe and a few truly arid deserts in the rain shadow of the Cascades; the Hanford reservation receives an average annual precipitation of 6 to 7 inches (150 to 180 mm). Despite the limited amount of rainfall, agriculture
13300-555: The crust, which allows the hotter, and therefore lighter and more buoyant, mantle material to rise higher. This is believed by many to be involved with the Yellowstone hotspot and Columbia River Basalts ; the nature of such involvement, if any, is hotly debated. While the Yellowstone hotspot and Columbia River Basalts do not seem to directly interact with the OWL, clarification of their origin and context might explain some of
13440-664: The east it follows a gravity gradient, much like the Klamath–;Blue Mountain Lineament (see below ) does. The significance of all this is not known. Past the Wallula Gap the OWL is identified with the Wallula Fault Zone, which heads towards the Blue Mountains . The Wallula Fault Zone is active, but whether that can be attributed to the OWL is unknown: it may be that, like the Yakima Fold Belt, it
13580-536: The east, bounded mostly by the meridian running north from the confluence of the Snake River and Clearwater River (about 117°02'23" west), except for the southernmost section where the border follows the Snake River. Oregon is to the south, with the Columbia River forming the western part and the 46th parallel forming the eastern part of the Oregon–Washington border. During Washington's partition from Oregon,
13720-536: The east, it may curve to the west, or it may just end. Tabor mapped the SCF turning and merging with the Taneum fault (coincident with the OWL) south of Kachess Lake. This conforms with the general pattern seen in Lakes Keechelus, Kachess, and Cle Elum, and associated geological units and faults (see image, right): each is aligned north—south at the north end, but turns to the southeast where it approaches
13860-529: The entrance to the Strait of Juan de Fuca , but Cook did not realize the strait existed. It was not discovered until Charles William Barkley , captain of the Imperial Eagle , sighted it in 1787. The straits were further explored by Spanish explorers Manuel Quimper in 1790 and Francisco de Eliza in 1791, and British explorer George Vancouver in 1792. The British–Spanish Nootka Convention of 1790 ended Spanish claims of exclusivity and opened
14000-545: The following sections we will look at several features which might be expected to have some kind of structural relationship with the OWL, and consider what they might tell us about the OWL. The most notable geological feature crossing the OWL is the Cascade Range , raised up in the Pliocene (two to five million years ago) as a result of the Cascadia subduction zone . These mountains are distinctly different on either side of
14140-416: The interior of the continent. A problem in evaluating any hypothesis regarding the OWL is a dearth of evidence. Raisz suggested that the OWL might be a "transcurrent fault" (long strike-slip faults at what are now known to be plate boundaries), but lacked both data and competence to assess it. One of the first speculations that the OWL might be a major geological structure ( Wise 1963 ) – written when
14280-480: The manufacture of warships. Seattle was the point of departure for many soldiers in the Pacific, several of whom were quartered at Fort Lawton, which later became Discovery Park . In Eastern Washington, the Hanford Works atomic energy plant was opened in 1943 and played a major role in the construction of atomic bombs . After the end of World War II, and with the beginning of the civil rights movement ,
14420-632: The map) across the OWL, bowing the DDMFZ, and initiating the SCF and thereby splitting the Chuckanut Formation. On the north side of the DDMFZ, and wrapping around a bit to the east side, is a suite of distinctive rocks – the Helena—Haystack mélange ("HH Melange" on the map) – which was collapsed into vertical folds. Similarly distinctive rock is found in Manastash Ridge (shown on the map, but almost too small to see) still lying on
14560-528: The most prominent reptiles and amphibians. Coastal bays and islands are often inhabited by plentiful amounts of shellfish and whales. There are five species of salmon that ascend the Western Washington area, from streams to spawn. Walker Lane The Walker Lane is a geologic trough roughly aligned with the California / Nevada border southward to where Death Valley intersects
14700-573: The next few decades failed to settle upon a compromise boundary and the Oregon boundary dispute was highly contested between Britain and the United States. Disputed joint occupancy by Britain and the U.S. lasted for several decades. With American settlers pouring into Oregon Country , Hudson's Bay Company , which had previously discouraged settlement because it conflicted with the fur trade, reversed its position in an attempt to maintain British control of
14840-464: The north Pacific Ocean, the continental air masses of North America, and the Olympic and Cascade mountains. In the spring and summer, a high-pressure anticyclone system dominates the north Pacific Ocean, causing air to spiral out in a clockwise fashion. For Washington, this means prevailing winds from the northwest bring relatively cool air and a predictably dry season . In the autumn and winter,
14980-634: The north side (Seattle Basin, Kittitas Valley, Pasco Basin, Walla Walla Basin) and mountains on the southern side (the Olympics, Manastash and Umtanum ridges, Rattlesnake Mountain, the Horseheaven Hills, the Wallowa Mountains), and noted parallel alignments at various points, generally about four miles north or south of the main line. The alignment of these particular features is somewhat irregular; modern maps with much more detail show
15120-616: The northeast side of the Wallowa Mountains. However, there is a sense that the trend of the faulting in that area turns more to the south; it has been suggested the faulting associated with the OWL takes a large step south to the Vale Fault Zone, which connects with the Snake River Fault Zone in Idaho. Both of these lines introduce a bend into the OWL. The Imnaha Fault (striking towards Riggins, Idaho )
15260-533: The oldest and most complete human remains found in North America, were discovered in Washington in the 1990s. The region has been home to many established tribes of indigenous peoples for thousands of years. They are notable for their ornately carved welcome figures, canoes, long houses and masks. Prominent among their industries were salmon fishing and, notably among the Makah , whale hunting. The peoples of
15400-540: The one and only official Constitution of the State of Washington. Washington became the 42nd state of the United States on November 11, 1889. Early prominent industries in the new state included agriculture and lumber. In Eastern Washington, the Yakima River Valley became known for its apple orchards, while the growth of wheat using dry farming techniques became particularly productive. Heavy rainfall to
15540-504: The original plan for the border followed the Columbia River east until the confluence with the Snake, and then would have followed the Snake River east; this was changed to keep Walla Walla 's fertile farmland in Washington. To the west of Washington lies the Pacific Ocean. Its northern border lies mostly along the 49th parallel , and then via marine boundaries through the Strait of Georgia , Haro Strait , and Strait of Juan de Fuca , with
15680-436: The paleomagnetic rotation reflects actual block rotation; although the amount of rotation has been reduced (to perhaps only 28°), it seems it will not entirely go away. How this affects the postulated rifting does not seem to have been addressed. A more recent work based on analysis of GPS measurements concluded that "most of the Pacific Northwest can be described by a few large, rotating, elastic crustal blocks", but noted that in
15820-591: The production of electricity. This culminated in 1941 with the completion of the Grand Coulee Dam , the largest concrete structure in the United States and the largest dam in the world at its construction. During World War II, the state became a focus for war industries. While the Boeing Company produced many heavy bombers , ports in Seattle, Bremerton , Vancouver , and Tacoma were available for
15960-407: The red bar in the image) it is split by a distinct offset of several miles. Curiously, the southern section lies in the approximate zone of the OWL. (Note OWL–associated lineaments running parallel to the red line.) This suggests dextral offset along a strike-slip fault. But if that is the case then there should be a major fault in the vicinity of Port Madison and crossing to Seattle (perhaps at
16100-618: The relative motion of the Pacific plate past the North American plate, or possibly from the extension of the Basin and Range province ) as the primary driving force. The large values of paleomagnetic rotation are explained by a "ball bearing" model: the entire Oregon block (western Oregon including the Cascades and southwestern Washington) are deemed to be composed of many smaller blocks (on the scale of tens of kilometers), each of which rotates independently on its own axis. Evidence of such small blocks (at least in southwestern Washington) has been claimed. Later work has attempted to work out how much of
16240-534: The rest of the country, and for a time, it possessed a large shipbuilding industry. The region around eastern Puget Sound developed heavy industry during the period including World War I and World War II , and the Boeing company became an established icon in the area. During the Great Depression , a series of hydroelectric dams were constructed along the Columbia River as part of a project to increase
16380-471: The resulting gap the crust was stretched and thinned; the buoyancy of the hotter mantle have contributed to the subsequent rise of the Wallowa and Seven Devils Mountains, and perhaps also with the irruption of the Columbia River basalts and other basalt flows. While the rigid-block rotation model has much appeal, many geologists prefer another interpretation that minimizes whole–block rotation, and instead of rifting invokes "dextral shear" (resulting from
16520-542: The rifting does not seem to have been worked out yet. Certain complications in the subduction of the Kula and Farallon plates may have been involved.) During this rotation of the Coast Range the block of continental crust that is now the Blue Mountains (on the eastern side of the KBML) was also rifted away from the Idaho batholith, and also rotated about 50 degrees, but about a point near the Wallula Gap (or perhaps further east). In
16660-583: The same time many white patients recovered, they held "medicine man" Marcus Whitman personally responsible, and executed Whitman and twelve other white settlers. This was called the Whitman massacre in 1847. This event triggered the Cayuse War between settlers and Indians. Fort Nisqually , a farm and trading post of the Hudson's Bay Company and the first European settlement in the Puget Sound area,
16800-407: The south end of Lake Washington, the north side of Elliott Bay, the valley of the Ship Canal, the bluff along Interlaken Blvd. (aligned with the Ship Canal, but offset slightly to the north), the alignment of Ravenna Creek (draining Green Lake southeast into Union Bay) and Carkeek Creek (northwest into Puget Sound), various stream drainages around Lake Forest Park (north end of Lake Washington), and (on
16940-425: The south, Idaho to the east, and shares an international border with the Canadian province of British Columbia to the north. Olympia is the state capital , and the most populous city is Seattle . Washington is the 18th-largest state , with an area of 71,362 square miles (184,830 km ), and the 13th-most populous state, with more than 7.8 million people. The majority of Washington's residents live in
17080-505: The state on October 10, 1805. Explorer David Thompson , on his voyage down the Columbia River, camped at the confluence with the Snake River on July 9, 1811, and erected a pole and a notice claiming the territory for Great Britain and stating the intention of the North West Company to build a trading post at the site. Britain and the United States agreed to what has since been described as "joint occupancy" of lands west of
17220-464: The state's growing Black or African American population's wages were 53% above the national average. The early diversification of Washington through the Great Migration led to successful efforts at reducing discrimination in the workplace. In 1950, Seattle's first black representative for the state's legislature was elected. At the 1970 U.S. census , the black population grew to 7.13% of
17360-485: The state's land area, mostly west of the northern Cascades. Approximately two-thirds of Washington's forested area is publicly owned, including 64 percent of federal land. Common trees and plants in the region are camassia , Douglas fir, hemlock, penstemon , ponderosa pine, western red cedar , and many species of ferns. The state's various areas of wilderness offer sanctuary, with substantially large populations of shorebirds and marine mammals. The Pacific shore surrounding
17500-407: The state. In addition to Western Washington and Eastern Washington , residents call the two parts of the state the "Westside" and the "Eastside", "Wet side" and "Dry side", or "Timberland" and "Wheatland", the latter pair more commonly in the names of region-specific businesses and institutions. These terms reflect the geography, climate, and industry of the land on both sides of the Cascades. From
17640-513: The state— is 50 miles (80 km) south of the city of Seattle, from which it is prominently visible. The U.S. Geological Survey considers 14,411-foot-tall (4,392 m) Mount Rainier the most dangerous volcano in the Cascade Range, due to its proximity to the Seattle metropolitan area , and most dangerous in the continental U.S. according to the Decade Volcanoes list. It is also covered with more glacial ice than any other peak in
17780-648: The territory of both the Cayuse and the Nez Perce Indian tribes. Whitman's settlement would in 1843 help the Oregon Trail , the overland emigration route to the west, get established for thousands of emigrants in the following decades. Whitman provided medical care for the Native Americans, but when Indian patients—lacking immunity to new, "European" diseases—died in striking numbers, while at
17920-435: The theory of plate tectonics was still new and not entirely accepted – was called by the author "an outrageous hypothesis". Modern investigation is still largely balked by the immense span of geography involved and lack of continuous structures, the lack of clearly cross-cutting features, and a confusing expression in both rock millions of years old and glacial sediments only 16,000 years old. Geological investigation of
18060-501: The topography suggests no such turn. Displacement, to either the west or the east, seems unlikely in that certain effects that would be expected are not found. Could the SCF just end? This is difficult to comprehend. If there is displacement along this fault, where did it come from? To quote Wyld et al. (albeit in the context of a different fault): "it cannot just end". Although the SCF has had substantial strike-slip displacement, Vance & Miller (1994) claim that final major movement on
18200-472: The total population. In 1970, the state was one of only four U.S. states to have been providing legal abortions before the 1973 Supreme Court decision in Roe v. Wade which loosened abortion laws nationwide. On May 18, 1980, following a period of heavy tremors and small eruptions, the north face of Mount St. Helens slid off in the largest landslide in recorded history before erupting violently , destroying
18340-415: The tropical Pacific regions a great distance into the Pacific Northwest. Western Washington is very cloudy during much of fall, winter, and early spring. Seattle averages the least sunshine hours of any major city in the United States. Despite Western Washington's marine climate similar to many coastal cities of Europe, there are exceptions such as the "Big Snow" events of 1880, 1881, 1893, and 1916, and
18480-483: The underlying structure is not known; geophysical data does not indicate a major fault nor any kind of crustal boundary along the front of the Seattle Fault, nor along the OWL, but this could be due to the limited reach of geophysical methods. Recent geological mapping at the eastern side of the Seattle Fault suggests a decollement (horizontal plane) about 18 km deep. These models were developed in study of
18620-492: The west of the Cascade Range produced dense forests, and the ports along Puget Sound prospered from the manufacturing and shipping of lumber products, particularly the Douglas fir . Other industries that developed in the state included fishing, salmon canning and mining. For a long period, Tacoma had large smelters where gold, silver, copper, and lead ores were treated. Seattle was the primary port for trade with Alaska and
18760-539: The west, and similarly for the Blue Mountains, but this is questionable, and similar offsets are not apparent in the older – up to 17 Ma ( millions of years ) old – Columbia River basalt flows . In general, there are no clear indications of structures offset by the OWL, but neither are there any distinct features crossing the OWL (and older than 17 Ma) that positively demonstrate a lack of offsetting. The Straight Creek Fault (SCF) – just east of Snoqualmie Pass and running nearly due north into Canada –
18900-418: The western segment of the Seattle Fault. In the center segment, where it crosses surface exposures of Eocene rock associated with the OWL, the various strands of the fault – elsewhere fairly orderly – meander. The significance of this and the nature of the interaction with the Eocene rock are also not known. Examination of the various strands of the Seattle Fault, particularly in the central section,
19040-460: The wide dispersal of this rock is difficult; many geologists see no alternative to transport along an extended SCF. But that upsets some of the "solutions" described above, and there is yet no consensus on this. Further east is the "CLEW", the segment of the OWL from approximately the town of Cle Elum (marking the western limit of the Columbia River basalts) to the Wallula Gap (a narrow gap on
19180-796: The winter and warm, temperate summers. The eastern region, which does not benefit from the general moderating effect of the Pacific Ocean, occasionally experiences extreme climate. Arctic cold fronts in the winter and heat waves in the summer are not uncommon. In the Western region, temperatures have reached as high as 118 °F (48 °C) in Maple Valley during the June 2021 heat wave , and as low as −6 °F (−21 °C) in Longview , and even -8 F (-22 C) in Sammamish . Forests cover about half
19320-412: Was among the first states to introduce same-sex marriage , and was one of only four states to have provided legal abortions on request before Roe v. Wade in 1973. Washington voters also approved a 2008 referendum on the legalization of physician-assisted suicide , making it one of 10 states to have legalized the practice. Washington was named after President George Washington by an act of
19460-663: Was formed from the western part of the Washington Territory , which was ceded by the British Empire in the Oregon Treaty of 1846. It was admitted to the Union as the 42nd state in 1889. One of the wealthiest and most socially liberal states in the country, Washington consistently ranks among the top states for highest life expectancy and employment rates. It was one of the first states (alongside Colorado ) to legalize medicinal and recreational cannabis ,
19600-483: Was founded in 1833. Black pioneer George Washington Bush and his Caucasian wife, Isabella James Bush, from Missouri and Tennessee , respectively, led four white families into the territory and founded New Market, now Tumwater , in 1846. They settled in Washington to avoid Oregon 's black exclusion law , which prohibited African Americans from entering the territory while simultaneously prohibiting slavery . After them, many more settlers, migrating overland along
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