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170:
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formed magma ascends upward through the crust along a path of least resistance, both by way of fractures and faults as well as by melting wall rocks. The addition of melted crust changes the geochemical composition. Some of the melt rises toward the Earth's surface to erupt, forming a chain of volcanoes (the
Cascade Volcanic Arc) above the subduction zone. The addition of crustal melt to the original mantle melt results in volcanic and plutonic rocks that differ in mineralogy from the mantle source.
265:. Where the Juan de Fuca Plate sinks beneath the North American Plate there is no deep trench, seismicity (earthquakes) is less than expected, and there is evidence of a decline in volcanic activity over the past few million years. The probable explanation lies in the rate of convergence between the Juan de Fuca and North American Plates. These two plates converge at 3–4 centimetres (1.2–1.6 in) per year at present. This is only about half the rate of convergence of 7 million years ago.
395:
139:. The Cascade Volcanoes are an active volcanic region along the western side of the Pacific Northwest. The Columbia Plateau is a region of subdued geography that is inland of the Cascade Volcanoes, and the North Cascades are a mountainous region in the northwest corner of the United States, extending into British Columbia. The Coast Mountains and Insular Mountains are a strip of mountains along the coast of British Columbia, each with its own geological history.
1312:
314:
1222:. It started near Soap Lake in Washington State, where less resistant basalt layers gave way before the great erosive power of this tremendous torrent and waterfalls developed. As in the upper Grand Coulee, the raging river yanked chunks of rock from the face of the falls and the falls eventually retreated to their present location. Dry Falls is 5.6 km (3.5 mi) wide, with a drop of more than 120 m (400 ft). By way of comparison,
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284:
1425:
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1016:
1169:. Over the centuries, as snowfall exceeded melting and evaporation, a great accumulation of snow covered part of the continent, forming extensive ice fields. This vast continental ice sheet reached a thickness of about 1,200 m (4,000 ft) in some areas. Sufficient pressure on the ice caused it to flow outward as a glacier. The glacier moved south out of
697:
2160:
2039:
1996:
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1768:
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1293:, and then locally buried in their own eroded debris; other pieces were forced deep into the Earth to be heated and squeezed, almost beyond recognition, and then raised again to view. Over time, the moving plates eventually accreted the various pieces of the mosaic onto the western side of North America.
1071:
Like the
Columbia River region, volcanic eruptions dominate the story of the Snake River Plain in the eastern part of the Columbia Plateau Province. The earliest Snake River Plain eruptions began about 15 million years ago, just as the tremendous early eruptions of Columbia River Basalt were ending.
1199:
Glacial Lake
Missoula broke through the ice dam many times, allowing a tremendous volume of water to rush across northern Idaho and into eastern Washington. Such catastrophic floods raced across the southward-dipping plateau a number of times, etching the coulees which characterize this region, now
1104:
that forms Earth's moving tectonic plates). In an effort to figure out why this area, far from a plate boundary, had such an enormous outpouring of lava, scientists established hardening dates for many of the individual lava flows. They found that the youngest volcanic rocks were clustered near the
207:
sinks deep into the Earth's interior beneath the continental plate, high temperatures and pressures allow water molecules locked in the minerals of solid rock to escape. The supercritical water rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly
1033:
The
Columbia Plateau province is enveloped by one of the world's largest accumulations of basalt. Over 500,000 km (190,000 sq mi) of the Earth's surface is covered by it. The topography here is dominated by geologically young lava flows that inundated the countryside with amazing
329:
in southwestern
British Columbia is the northern extension of the Cascade Volcanic Arc in the United States and contains the most explosive young volcanoes in Canada. Like the rest of the arc, it has its origins in the Cascadia subduction zone. Volcanoes of the Garibaldi Volcanic Belt have been
1263:
Rocks of the North
Cascades record at least 400 million years of history. The record of this long history can be read in the many rock layers deposited over time through the forces of erosion, volcanic activity and plate subduction. These different forces have made a geologic mosaic made up of
1259:
In geology, the range has more in common with the Coast Ranges of
British Columbia and Alaska than it does with its Cordilleran cousins in the Rocky Mountains or Sierra Nevada. Although the peaks of the North Cascades do not reach great elevations (high peaks are generally in the 2,100 to
1211:, where the river roared over an 240 m (800 ft) waterfall. The eroding power of the water plucked pieces of basalt from the precipice, causing the falls to retreat 32 km (20 mi) and self-destruct by cutting through to the Columbia River valley near what is now the
1048:
stretches across Oregon, through northern Nevada, southern Idaho, and ends at the
Yellowstone Plateau in Wyoming. Looking like a great spoon scooped out the Earth surface, the smooth topography of this province forms a striking contrast with the strong mountainous fabric around it.
184:
get the most attention, the
Cascade Volcanic Arc includes a band of thousands of very small, short-lived volcanoes that have built a platform of lava and volcanic debris. Rising above this volcanic platform are a few strikingly large volcanoes that dominate the landscape.
390:
on the relation of the volcanoes north of that fault to the rest of the
Cascade Arc. However, the Pemberton Volcanic Belt is usually merged with the Garibaldi Volcanic Belt, making Mount Silverthrone the northernmost, but an uncertain Cascadia subduction-related volcano.
30:
1319:
The deep canyons and sharp peaks of today's North Cascades scene are products of profound erosion. Running water has etched out the grain of the range, landslides have softened the abrupt edges, homegrown glaciers have scoured the peaks and high valleys and, during the
1476:
in southwestern British Columbia are the southernmost subdivision of the Coast Mountains. It has been characterized by rapid rates of uplift over the past 4 million years unlike the North Cascades and has led to relatively high rates of erosion.
1097:, the fissures that fed flows and cone-building eruptions. Calderas, great pits formed by explosive volcanism, and low shield volcanoes, and rhyolite hills are also part of the landscape here, but many are obscured by later lava flows.
1041:, covers the western part of the province. These tremendous flows erupted between 17–6 million years ago. Most of the lava flooded out in the first 1.5 million years: an extraordinarily short time for such an outpouring of molten rock.
1146:
are ample evidence of a concentration of heat beneath the surface. The hotspot is probably quite stationary, but the North American plate is moving over it, creating a superb record of the rate and direction of plate motion.
1256:, and second only to the Alpine-Himalayan chain in height. Although only a small part of the Cordillera, mile for mile, the North Cascade Range is steeper and wetter than most other ranges in the contiguous United States.
1452:
occurring faster than uplift, have continued to flow right up to the present day, directly across the axis of the range. The mountains flanking the Homathko River are the highest in the Coast Mountains, and include
1280:
of the earth. The disparate pieces of the North Cascade mosaic were born far from one another but subsequently drifted together, carried along by the tectonic plates that make up the Earth's outer shell or were
1260:
2,400 m (7,000 to 8,000 ft) range, their overall relief, the relatively uninterrupted vertical distance from valley bottom to mountain top, is commonly 1,200 to 1,800 m (4,000 to 6,000 ft).
1300:. Volcanoes erupted to cover the older rocks with lava and ash. Large masses of molten rock invaded the older rocks from below. The volcanic arc is still active today, decorating the skyline with the cones of
1135:, some of the lighter rock of the lithosphere rapidly melts. It is this molten lithosphere that becomes the basalt lavas that gush onto the surface to form the Columbia River and Snake River Plain basalts.
1328:
overrode almost all the range and rearranged courses of streams. Erosion has written and still writes its own history in the mountains, but it has also revealed the complex mosaic of the bedrock.
413:(sometimes called the Stikine Volcanic Belt). It contains more than 100 young volcanoes and several eruptions known to have occurred within the last 400 years. The last eruptions within the
299:. More than 3,000 vents erupted during the most recent volcanic episode that began 5 million years ago. As long as subduction continues, new Cascade volcanoes will continue to rise.
528:
that extends several km to the north and east of the cone. The volcanic belt also contains three large shield volcanoes that were formed between 8 and 1 million years ago, called the
374:, may also be the product of Cascadia subduction, but geologic investigations have been very limited in this remote region. About 5–7 million years ago, the northern end of the
1960:
1889:
192:, an array of volcanoes that rim the Pacific Ocean. The Ring of Fire is also known for its frequent earthquakes. The volcanoes and earthquakes arise from a common source:
362:
off the coast, suggests that volcanism has not yet ended in the Garibaldi Volcanic Belt. A few isolated volcanic centers northwest of the Mount Meager massif such as the
1100:
Evidence suggests that some concentrated heat source is melting rock beneath the Columbia Plateau Province. At the base of the lithosphere (the layer of crust and
2320:
295:
The Cascade Volcanic Arc made its first appearance 36 million years ago, but the major peaks that rise up from today's volcanic centers were born within the
685:
657:
around the years 1750 or 1775 is Canada's worst known geophysical disaster. The eruption produced a 22.5 km (14.0 mi) long lava flow, destroying the
222:
made up of a series of breaks in the oceanic crust where melted mantle rises and solidifies, creating new ocean crust. On one side of the spreading ridge new
1361:. This is the single largest contiguous granite outcropping in the world, which extends approximately 1,800 km (1,100 mi) in length. It is a large
1083:. Not so in the Snake River Plain, where relatively quiet eruptions of soupy black basalt lava flows alternated with tremendous explosive eruptions of
2325:
334:, was responsible for a major catastrophic eruption that occurred about 2,350 years ago. This eruption may have been close in size to that of the
276:. The Explorer Plate broke away from the Juan de Fuca about 4 million years ago and shows no evidence that it is still being subducted. The
1864:
2310:
410:
2085:
1184:. The lake measured about 7,700 km (3,000 sq mi) and contained about 2,100 km (500 cu mi), half the volume of
2315:
972:
825:
571:
461:. It is the second largest persistent eruptive center within the Northern Cordilleran Volcanic Province and is flanked with numerous young
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and Mount Meager massifs suggest that magmatic heat is still present. The long history of volcanism in the region, coupled with continued
1713:
1350:
and most of coastal British Columbia. The range is approximately 1,600 km (1,000 mi) long and 200 km (120 mi) wide.
1207:
As the floods in this vicinity raced southward, two major cascades formed along their course. The larger cataract was that of the upper
1936:
1128:. The concentrated heat triggers a plume hundreds of kilometers in diameter that ascends directly through to the surface of the Earth.
2005:
901:
438:
335:
1851:
2276:
2169:
2175:
2013:
1826:
1783:
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1839:
469:. There are some indications that Level Mountain and Mount Edziza volcanic complex may be between 11 and 9 million years old.
96:
The geology of the Pacific Northwest is vast and complex. Most of the region began forming about 200 million years ago as the
988:
863:
418:
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992:
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166:, roughly parallel to the Pacific coastline. Within this region, nearly 20 major volcanic centers lie in sequence.
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time (about one million years ago), cooling temperatures provided conditions favorable for the creation of continental
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1703:
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period the Coast Mountains did not exist and a level peneplain extended to the sea. This mass was uplifted during the
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Magnetic anomalies around the Juan de Fuca and Gorda Ridges, off the west coast of North America, color coded by age.
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917:
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937:
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On the trail of the Ice Age floods : a geological field guide to the mid-Columbia basin / Bruce Bjornstad
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1241:
371:
326:
318:
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2264:
Reducing Earthquake Losses Throughout the United States: Averting Surprises in the Pacific Northwest (USGS)
2200:
U-Pb dates from the Scotia-Quaal metamorphic belt, Coast Plutonic Complex, central-western British Columbia
2101:
O’Connor, J.E.; Baker, V.R.; Waitt, R.B.; Smith, L.N.; Cannon, C.M.; George, D.L.; Denlinger, R.P. (2020).
1226:, 1.6 km (1 mi) wide with a drop of only 50 m (165 ft), would be dwarfed by Dry Falls.
913:
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933:
422:
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The Snake River Plain lies in a distinct depression. At the western end, the base has dropped down along
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volcanic field. The most voluminous and most persistent eruptive center within the belt and in Canada is
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The Coast Mountains are heavily eroded by glaciers, including Mount Waddington (far background, center).
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1181:
984:
929:
801:
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The Pacific Northwest volcanoes continue to be a geologically active area. The most geologically recent
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in southern British Columbia is a north–south range of volcanoes, thought to have formed as a result of
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material, is rising to the surface beneath the Columbia Plateau Province. Geologists know that beneath
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structure. Although there is extensive faulting at the eastern end, the structure is not as clear.
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638:
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A close-up look at the Cascades reveals a more complicated picture than a simple subduction zone.
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496:. It is thought to have formed as a result of the North American Plate moving over a stationary
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sporadically active over a time span of several millions of years. The northernmost member, the
280:
split away between 18 and 5 million years ago and continues to sink beneath North America.
2103:"The Missoula and Bonneville floods—A review of ice-age megafloods in the Columbia River basin"
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2081:
1954:
1883:
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1512:
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is responsible for many of the area's scenic features as well as some of its hazards, such as
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In addition, eleven volcanoes in Canada have had seismic activity since 1975, including: the
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is perhaps the shallowest seamount in Canada's Pacific waters. Because of its shallow depth,
17:
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2017:
1500:
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crust is made, then moves away from the ridge. On the other side of the spreading ridge the
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The immense floods created channels that are presently dry, such as the Drumheller Channels
104:. Since that date, the western edge of North America has grown westward as a succession of
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1574:
1520:
1406:
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743:
722:, Canada's most voluminous and most persistent eruptive center, might have erupted in the
595:
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132:
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1507:
are just the higher elevations of the range, which was in fact fully exposed during the
555:. The majority of the eruptions in this belt happened either 6 to 10 million years ago (
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29:
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But most of the Snake River Plain volcanic rock is less than a few million years old,
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Although scientists are still gathering evidence, a probable explanation is that a
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thinning. Some of the lava flows in the field are similar to those that erupted at
525:
398:
379:
355:
105:
62:
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About 35 million years ago, a volcanic arc grew across this complex mosaic of old
1124:, a temperature instability develops (for reasons not yet well understood) at the
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In the west, the Columbia River Basalts are just that: almost exclusively black
1683:
1586:
1527:, the Insular Mountains are the true westernmost range. Through the most recent
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1301:
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The most active volcanic region of the northern Pacific Northwest is called the
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Yellowstone Plateau, and that the farther west they went, the older the lavas.
684:. Today, the basaltic lava deposits are a draw to tourists and are part of the
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1594:
1578:
1402:
1370:
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are the western range of the North American mainland cordillera, covering the
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843:
837:
753:
729:
700:
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517:
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1248:, a mountain chain stretching more than 19,000 km (12,000 mi) from
1037:
Over 170,000 km (41,000 cu mi) of basaltic lava, known as the
1693:
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1582:
1496:
1362:
1219:
673:
634:
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90:
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valley was inundated by the lava flows and contain abundant tree molds and
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flows that have been active for the past 3 million years. It is within the
524:
that traveled 1 km (0.6 mi) to the west, along with a blanket of
158:
The Cascades Province forms an arc-shaped band extending from southwestern
2263:
2230:
1637:
worldwide, exposing up to 6,000 m (20,000 ft) of basal sediment-
199:
Beneath the Cascade Volcanic Arc, a dense oceanic plate sinks beneath the
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1536:
1433:
1398:
1382:
1084:
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847:
723:
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46:
441:. The broad dissected summit region consists of trachytic and rhyolitic
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that covers an area of 1,800 km (690 sq mi) southwest of
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at least three times during the past 7,300 years. Hot springs near the
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101:
82:
1173:, damming rivers and creating lakes in Washington, Idaho and Montana.
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757:
704:
677:
594:. The origin of the volcanism is unknown, but is probably related to
579:
446:
343:
2006:"Geologic Provinces of the United States: Columbia Plateau Province"
1852:
Catalogue of Canadian volcanoes: Wells Gray-Clearwater volcano field
1558:
1093:
dot the landscape of the Snake River Plain. Some are aligned along
53:), structure, physical properties and the processes that shape the
1663:
1557:
1495:
on the coast of British Columbia have not yet fully emerged above
1432:
The Coast Mountains consist of a single uplifted mass. During the
1423:
1310:
1190:
1062:
1014:
912:
695:
610:
occurs. The last eruption in the field was about 400 years ago at
603:
471:
393:
312:
282:
252:
236:
188:
The Cascade volcanoes define the Pacific Northwest section of the
168:
50:
28:
828:
might have erupted and formed in 1500 based on tree-ring dating.
680:
explorers to penetrate the uncharted coastal waters of northern
607:
583:
521:
347:
1593:
that make the Coast Mountains. The Insular Mountains have much
1138:
The track of this hot spot starts in the west and sweeps up to
2233:
in the Canadian Mountain Encyclopedia. Retrieved on 2007-12-02
2221:
in the Canadian Mountain Encyclopedia. Retrieved on 2007-12-02
1565:
on Vancouver Island was formed by erosion carving into basalt.
1532:
794:, Canada's second largest eruptive center, erupted about 1340
1067:
A map of the Snake River Plain, showing its smooth topography
520:. It last erupted about 7,000 years ago, producing two small
956:(magnitude 6.8) struck 16 km (10 mi) northeast of
1523:
are commonly considered to be the westernmost range of the
338:. Ash from this eruption can be traced eastward to western
272:
and Gorda Plate are the meager remnants of the much larger
766:, which erupted catastrophically in 5670 BCE to form
641:. The Bowie Seamount is also the youngest seamount in the
1019:
The Columbia River basalts cover portions of three states
870:, producing a 22.5 km (14.0 mi) long lava flow.
108:
and assorted ocean-floor rocks have been added along the
1397:
and continental margin assemblages accreted between the
637:
believe it was an active volcanic island throughout the
590:, which also includes the 142 m (465 ft)-high
1633:, which is perhaps the thickest accreted section of an
1613:. Large earthquakes have led to collapsing mountains,
882:
erupted in 1880; fumaroles still occur at its summit.
488:
is a volcanic belt that stretches from just north of
676:. The event coincided with the arrival of the first
621:
lie off British Columbia's coast and are related to
457:
is perhaps the most spectacular volcanic edifice in
268:
The small Juan de Fuca Plate and two platelets, the
1905:"Dating the Bonneville Landslide with Lichenometry"
1842:-Map of Canadian volcanoes. Retrieved on 2007-06-24
445:and was considered to be dotted with several minor
1389:periods. The plutonic complex is built on unusual
1315:The North Cascades are heavily eroded by glaciers
924:The Pacific Northwest is seismically active. The
664:and the death of at least 2000 Nisga'a people by
563:). However, there have been few eruptions in the
1959:: CS1 maint: bot: original URL status unknown (
1888:: CS1 maint: bot: original URL status unknown (
1577:, collided against North America during the Mid-
100:started to drift westward during the rifting of
1569:The Insular Mountains were formed when a large
944:in Japan, and may have temporarily blocked the
1865:"Great Cascadia Earthquake Penrose Conference"
1131:When the hot plume arrives at the base of the
449:vents of postglacial age, although considered
350:and rock several meters (yards) deep into the
2080:. Sandpoint, Idaho: Keokee Books. p. 4.
1034:speed, all within the last 17 million years.
386:, and there is no definitive consensus among
8:
2154:
2152:
2150:
2148:
2146:
2144:
1990:
1353:Most of the Coast Mountains are composed of
960:, causing some structural damage and panic.
814:might have eruptions younger than 1000
1988:
1986:
1984:
1982:
1980:
1978:
1976:
1974:
1972:
1970:
1076:age (5–1.6 million years ago) and younger.
1942:. Archived from the original on 2006-05-28
1871:. Archived from the original on 2004-08-17
1805:
1803:
1801:
1799:
1797:
1795:
1793:
1762:
1760:
686:Nisga'a Memorial Lava Beds Provincial Park
629:located 180 km (110 mi) west of
1276:, and even pieces of the deep subcrustal
1218:The other major cataract is now known as
900:erupted in 1980, killing 57 people. (see
1903:Reynolds, Nathaniel D. (December 2001).
342:. It is also the most unstable volcanic
203:; a process known as subduction. As the
2053:Lake Roosevelt National Recreation Area
1756:
1142:. The steaming fumaroles and explosive
261:There are some unusual features at the
2033:
2031:
2029:
2027:
1952:
1881:
784:20 km (12 mi) high into the
465:, including the young, well-preserved
411:Northern Cordilleran Volcanic Province
2321:Regional geology of the United States
2255:Good text on the geology of Cascadia.
1421:areas are of recent volcanic origin.
1365:complex. Its formation is related to
707:, erupted roughly 5000 years BCE
500:, similar to the hotspot feeding the
7:
1822:Pacific – Cascades Volcanic Province
1779:Pacific – Cascades Volcanic Province
1126:boundary between the core and mantle
973:Wells Gray-Clearwater volcanic field
936:9: the last such earthquake was the
834:erupted in the 17th or 18th century.
826:Wells Gray-Clearwater volcanic field
572:Wells Gray-Clearwater volcanic field
245:that produced the magnitude 8.7–9.2
180:Although the largest volcanoes like
41:includes the composition (including
1714:Geology of the Lassen volcanic area
1649:, and thick, massive basalt flows.
1465:east of the river, adjacent to the
2253:Evolution of the Pacific Northwest
1581:period. The mountains are made of
25:
1645:to picritic pillow lavas, pillow
1268:, deep ocean sediments, basaltic
1112:, an extremely hot plume of deep
1087:, a light-colored volcanic rock.
902:1980 eruption of Mount St. Helens
336:1980 eruption of Mount St. Helens
2326:Geology of the Pacific Northwest
2163: This article incorporates
2158:
2042: This article incorporates
2037:
1999: This article incorporates
1994:
1814: This article incorporates
1809:
1771: This article incorporates
1766:
405:in northwestern British Columbia
39:geology of the Pacific Northwest
33:The Pacific Northwest from space
2249:Geologic history of Washington.
2176:United States Geological Survey
2127:10.1016/j.earscirev.2020.103181
2076:Bjornstad, Bruce N. (c. 2006).
2014:United States Geological Survey
1869:USGS Earthquake Hazards Program
1827:United States Geological Survey
1784:United States Geological Survey
1448:predate this uplift and due to
952:. More recently, in 2001, the
920:after the Nisqually earthquake
760:erupted about 7,000 years ago.
732:, the youngest volcano in the
453:activity to be uncertain. The
303:Volcanism outside the Cascades
1:
2311:Geology of Washington (state)
2274:On the eruption of Mt. Meager
2259:One link on Northwest geology
993:Mount Edziza volcanic complex
792:Mount Edziza volcanic complex
455:Mount Edziza volcanic complex
214:Not far off the coast of the
18:Geology of Washington (state)
840:erupted in the 18th century.
559:) or 2–3 million years ago (
346:in Canada, which has dumped
61:. The region is part of the
2316:Geology of British Columbia
1724:List of volcanoes in Canada
1704:Geology of British Columbia
1689:Columbia River Basalt Group
1660:Beaverhead impact structure
1625:on Vancouver Island form a
1535:enclosed nearly all of the
1440:period. Rivers such as the
1272:, parts of old continents,
1240:The North Cascade Range in
1039:Columbia River Basalt Group
1029:Columbia River Basalt Group
888:might have erupted in 1898.
643:Kodiak-Bowie Seamount chain
417:was about 150 years ago at
297:last 1.6 million years
247:Cascadia earthquake in 1700
2342:
1589:unlike the plutons of the
1484:
1405:periods. In addition, the
1377:tectonic plates along the
1335:
1233:
1161:With the beginning of the
1154:
1022:
588:Wells Gray Provincial Park
578:consists of several small
306:
218:lies a spreading ridge; a
151:
2010:USGS Geology in the Parks
1729:Olympic–Wallowa Lineament
1617:, and the development of
1515:in this area was a broad
1457:west of the river in the
1140:Yellowstone National Park
850:on the summit still spew
668:and poisonous smoke. The
653:The last eruption of the
2269:USGS site on earthquakes
1709:Geology of North America
1679:Cascadia subduction zone
1603:Cascadia subduction zone
1531:about 18,000 years ago,
938:1700 Cascadia earthquake
928:is capable of producing
804:erupted about 1000
776:erupted about 2350
692:Recent volcanic activity
582:volcanoes and extensive
553:Cascadia subduction zone
364:Franklin Glacier Complex
220:divergent plate boundary
115:There are at least five
2202:Retrieved on 2007-12-02
1854:Retrieved on 2007-07-25
1699:Garibaldi Volcanic Belt
1357:, which is part of the
372:Pemberton Volcanic Belt
327:Garibaldi Volcanic Belt
319:Garibaldi Volcanic Belt
263:Cascade subduction zone
2171:North Cascades Geology
2165:public domain material
2044:public domain material
2001:public domain material
1816:public domain material
1773:public domain material
1591:Coast Plutonic Complex
1566:
1429:
1359:Coast Plutonic Complex
1316:
1196:
1068:
1020:
930:megathrust earthquakes
921:
708:
481:
423:Iskut-Unuk River Cones
406:
322:
292:
274:Farallon oceanic plate
258:
250:
234:plates move eastward.
177:
176:erupts on May 18, 1980
34:
2247:Burke Museum web site
2107:Earth-Science Reviews
2057:National Park Service
1937:"Volcanoes of Canada"
1744:Volcanology of Canada
1611:Queen Charlotte Fault
1561:
1543:that ran down to the
1427:
1326:Cordilleran Ice Sheet
1314:
1194:
1182:Glacial Lake Missoula
1066:
1018:
916:
802:Medicine Lake Volcano
699:
475:
397:
316:
286:
256:
240:
172:
148:The Cascade Volcanoes
32:
1176:The ice blocked the
965:Silverthrone Caldera
954:Nisqually earthquake
846:erupted in 1781–82;
812:Silverthrone Caldera
736:, erupted 7200
734:Anahim Volcanic Belt
486:Anahim Volcanic Belt
478:Anahim Volcanic Belt
378:broke off along the
368:Silverthrone Caldera
201:North American Plate
98:North American Plate
79:North American Plate
2119:2020ESRv..20803181O
1840:Volcanoes of Canada
1631:Karmutsen Formation
1525:American cordillera
1246:American cordillera
1202:channeled scablands
1180:, forming the huge
969:Mount Meager massif
958:Olympia, Washington
940:, which produced a
774:Mount Meager massif
608:olivine nephelinite
370:, which lie in the
332:Mount Meager massif
309:Volcanism in Canada
164:Northern California
2279:2007-04-17 at the
2217:2007-12-17 at the
1912:Washington Geology
1734:Puget Sound faults
1719:Hole-in-the-Ground
1627:geologic formation
1609:sliding along the
1601:subducting at the
1599:Juan de Fuca Plate
1567:
1430:
1379:continental margin
1317:
1230:The North Cascades
1197:
1151:The Ice Age floods
1069:
1021:
926:Juan de Fuca Plate
922:
894:erupted in 1914–5.
866:erupted about 150
746:erupted 7050
713:volcanic eruptions
709:
649:Volcanic disasters
549:back-arc extension
482:
407:
376:Juan de Fuca Plate
323:
293:
259:
251:
243:Juan de Fuca Plate
178:
117:geologic provinces
110:continental margin
35:
2301:Geology of Oregon
2296:Pacific Northwest
2231:Insular Mountains
2087:978-1-879628-27-4
1674:Cascade Volcanoes
1513:continental shelf
1493:Insular Mountains
1487:Insular Mountains
1481:Insular Mountains
1467:Homathko Icefield
1046:Snake River Plain
574:in south-eastern
154:Cascade Volcanoes
137:Insular Mountains
121:Cascade Volcanoes
119:in the area: the
55:Pacific Northwest
16:(Redirected from
2333:
2306:Geology of Idaho
2234:
2228:
2222:
2209:
2203:
2197:
2191:
2190:
2188:
2187:
2178:. Archived from
2162:
2161:
2156:
2139:
2138:
2098:
2092:
2091:
2073:
2067:
2066:
2064:
2063:
2041:
2040:
2035:
2022:
2021:
2016:. Archived from
1998:
1997:
1992:
1965:
1964:
1958:
1950:
1948:
1947:
1941:
1933:
1927:
1926:
1924:
1923:
1909:
1900:
1894:
1893:
1887:
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1877:
1876:
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1855:
1849:
1843:
1837:
1831:
1830:
1813:
1812:
1807:
1788:
1787:
1770:
1769:
1764:
1595:seismic activity
1563:The Golden Hinde
1501:Vancouver Island
1463:Mount Queen Bess
1459:Waddington Range
1455:Mount Waddington
1442:Klinaklini River
1395:oceanic plateaus
1348:Alaska Panhandle
1254:Alaska Peninsula
1250:Tierra del Fuego
1213:Grand Coulee Dam
1178:Clark Fork River
1025:Columbia Plateau
1011:Columbia Plateau
950:Bonneville Slide
934:moment magnitude
909:Seismic activity
898:Mount St. Helens
860:erupted in 1786.
682:British Columbia
600:Volcano Mountain
576:British Columbia
502:Hawaiian Islands
490:Vancouver Island
459:British Columbia
429:. It is a large
352:Pemberton Valley
182:Mount St. Helens
174:Mount St. Helens
160:British Columbia
125:Columbia Plateau
21:
2341:
2340:
2336:
2335:
2334:
2332:
2331:
2330:
2286:
2285:
2281:Wayback Machine
2243:
2238:
2237:
2229:
2225:
2219:Wayback Machine
2212:Coast Mountains
2210:
2206:
2198:
2194:
2185:
2183:
2168:
2159:
2157:
2142:
2100:
2099:
2095:
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2075:
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2038:
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2025:
2004:
1995:
1993:
1968:
1951:
1945:
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1939:
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1934:
1930:
1921:
1919:
1907:
1902:
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1897:
1880:
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1846:
1838:
1834:
1819:
1810:
1808:
1791:
1776:
1767:
1765:
1758:
1753:
1748:
1655:
1635:oceanic plateau
1575:Insular Islands
1555:their bottoms.
1521:Coast Mountains
1519:. Although the
1489:
1483:
1344:Coast Mountains
1340:
1338:Coast Mountains
1334:
1332:Coast Mountains
1244:is part of the
1238:
1232:
1159:
1157:Missoula Floods
1153:
1031:
1023:Main articles:
1013:
997:Hoodoo Mountain
977:Mount Garibaldi
918:State Route 302
911:
744:Hoodoo Mountain
694:
651:
625:volcanism. The
545:Chilcotin Group
508:. The youngest
463:satellite cones
439:Telegraph Creek
311:
305:
291:eruption column
156:
150:
145:
133:Coast Mountains
75:Farallon Plates
23:
22:
15:
12:
11:
5:
2339:
2337:
2329:
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2323:
2318:
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2298:
2288:
2287:
2284:
2283:
2271:
2266:
2261:
2256:
2250:
2242:
2241:External links
2239:
2236:
2235:
2223:
2204:
2192:
2140:
2093:
2086:
2068:
2023:
2020:on 2006-09-22.
1966:
1928:
1895:
1856:
1844:
1832:
1789:
1755:
1754:
1752:
1749:
1747:
1746:
1741:
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1701:
1696:
1691:
1686:
1681:
1676:
1671:
1666:
1656:
1654:
1651:
1547:sharpened the
1485:Main article:
1482:
1479:
1474:Pacific Ranges
1446:Homathko River
1336:Main article:
1333:
1330:
1274:submarine fans
1236:North Cascades
1234:Main article:
1231:
1228:
1155:Main article:
1152:
1149:
1012:
1009:
946:Columbia River
910:
907:
906:
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751:
741:
727:
720:Level Mountain
693:
690:
666:volcanic gases
650:
647:
627:Bowie Seamount
592:Helmcken Falls
530:Ilgachuz Range
506:Anahim hotspot
431:shield volcano
427:Level Mountain
403:shield volcano
384:Explorer Plate
307:Main article:
304:
301:
278:Gorda platelet
270:Explorer Plate
152:Main article:
149:
146:
144:
141:
129:North Cascades
24:
14:
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2182:on 2008-01-13
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2019:
2015:
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1669:Cascade Range
1667:
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1661:
1658:
1657:
1652:
1650:
1648:
1644:
1640:
1636:
1632:
1628:
1624:
1623:Flood basalts
1620:
1616:
1612:
1608:
1607:Pacific Plate
1604:
1600:
1596:
1592:
1588:
1584:
1580:
1576:
1573:, called the
1572:
1564:
1560:
1556:
1554:
1550:
1546:
1545:Pacific Ocean
1542:
1538:
1534:
1530:
1526:
1522:
1518:
1517:coastal plain
1514:
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1502:
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1229:
1227:
1225:
1224:Niagara Falls
1221:
1216:
1214:
1210:
1205:
1203:
1200:known as the
1193:
1189:
1187:
1186:Lake Michigan
1183:
1179:
1174:
1172:
1168:
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1158:
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1082:
1077:
1075:
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1061:
1059:
1055:
1054:normal faults
1050:
1047:
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1026:
1017:
1010:
1008:
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1002:
998:
994:
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908:
903:
899:
896:
893:
890:
887:
886:Ruby Mountain
884:
881:
878:
876:erupted 1854.
875:
874:Mount Rainier
872:
869:
865:
862:
859:
856:
853:
849:
845:
842:
839:
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827:
823:
820:
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813:
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797:
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790:
787:
783:
780:, sending an
779:
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749:
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585:
581:
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568:
566:
562:
558:
554:
550:
546:
541:
539:
535:
534:Rainbow Range
531:
527:
523:
519:
515:
514:volcanic belt
511:
507:
504:, called the
503:
499:
495:
491:
487:
479:
474:
470:
468:
464:
460:
456:
452:
448:
444:
440:
437:and north of
436:
432:
428:
424:
420:
416:
415:volcanic belt
412:
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271:
266:
264:
255:
248:
244:
241:Image of the
239:
235:
233:
229:
225:
224:Pacific Plate
221:
217:
216:North Pacific
212:
209:
206:
202:
197:
195:
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186:
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167:
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111:
107:
103:
99:
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88:
84:
80:
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72:
68:
64:
60:
59:North America
56:
52:
48:
44:
40:
31:
27:
19:
2226:
2207:
2195:
2184:. Retrieved
2180:the original
2170:
2110:
2106:
2096:
2077:
2071:
2060:. Retrieved
2052:
2018:the original
2009:
1944:. Retrieved
1931:
1920:. Retrieved
1918:(3/4): 11–16
1915:
1911:
1898:
1873:. Retrieved
1868:
1859:
1847:
1835:
1821:
1778:
1587:pillow lavas
1568:
1509:last ice age
1490:
1471:
1431:
1419:Silverthrone
1352:
1341:
1318:
1306:Glacier Peak
1295:
1262:
1258:
1239:
1217:
1209:Grand Coulee
1206:
1198:
1175:
1160:
1137:
1130:
1107:
1102:upper mantle
1099:
1091:Cinder cones
1089:
1078:
1070:
1056:, forming a
1051:
1043:
1036:
1032:
981:Mount Cayley
962:
923:
858:Mount Shasta
832:Glacier Peak
786:stratosphere
764:Mount Mazama
710:
652:
639:last ice age
616:
569:
542:
526:volcanic ash
483:
408:
399:Mount Edziza
382:to form the
380:Nootka Fault
356:Mount Cayley
324:
294:
267:
260:
228:Juan de Fuca
213:
210:
205:oceanic slab
198:
190:Ring of Fire
187:
179:
157:
114:
95:
63:Ring of Fire
38:
36:
26:
2113:(1): 1–53.
1684:Challis Arc
1641:complexes,
1629:called the
1597:, with the
1505:Haida Gwaii
1393:fragments,
1381:during the
1302:Mount Baker
1270:ocean floor
1266:island arcs
1163:Pleistocene
1133:lithosphere
1001:Crow Lagoon
989:The Volcano
985:Castle Rock
892:Lassen Peak
880:Mount Baker
864:The Volcano
822:Kostal Cone
768:Crater Lake
631:Haida Gwaii
612:Kostal Cone
565:Pleistocene
551:behind the
538:Itcha Range
512:within the
476:Map of the
419:The Volcano
317:Map of the
289:Lassen Peak
106:island arcs
87:earthquakes
2290:Categories
2186:2007-04-22
2062:2007-04-23
1946:2007-06-24
1922:2009-09-07
1875:2007-04-23
1751:References
1615:landslides
1579:Cretaceous
1571:island arc
1551:faces and
1403:Cretaceous
1391:island arc
1367:subduction
1242:Washington
1005:Nazko Cone
844:Mount Hood
838:Tseax Cone
782:ash column
754:Lava Butte
730:Nazko Cone
701:Lava Butte
674:lava tubes
670:Nass River
655:Tseax Cone
635:scientists
522:lava flows
518:Nazko Cone
443:lava domes
435:Dease Lake
401:, a large
388:geologists
360:subduction
194:subduction
135:, and the
91:landslides
77:under the
67:subduction
57:region of
2135:219072904
2049:"Geology"
1694:Fort Rock
1583:turbidite
1537:mountains
1511:when the
1497:sea level
1407:Garibaldi
1363:batholith
1264:volcanic
1220:Dry Falls
948:with the
852:sulfurous
848:fumaroles
715:include:
619:seamounts
617:Numerous
287:May 1915
143:Volcanoes
83:volcanoes
2277:Archived
2215:Archived
1955:cite web
1884:cite web
1739:Siletzia
1653:See also
1643:basaltic
1619:fissures
1605:and the
1541:Glaciers
1434:Pliocene
1401:and the
1399:Triassic
1383:Jurassic
1375:Farallon
1298:terranes
1283:uplifted
1167:glaciers
1110:hot spot
1085:rhyolite
1074:Pliocene
724:Holocene
678:European
662:villages
606:, where
580:basaltic
561:Pliocene
536:and the
492:to near
480:centers.
467:Eve Cone
451:Holocene
447:basaltic
366:and the
321:centers.
47:minerals
2115:Bibcode
1647:breccia
1529:ice age
1450:erosion
1438:Miocene
1369:of the
1355:granite
1322:Ice Age
1291:streams
1252:to the
1144:geysers
1122:Iceland
942:tsunami
824:in the
659:Nisga'a
623:hotspot
602:in the
596:crustal
557:Miocene
510:volcano
498:hotspot
494:Quesnel
421:in the
340:Alberta
102:Pangaea
71:Pacific
69:of the
2133:
2084:
1553:eroded
1549:valley
1499:, and
1415:Cayley
1411:Meager
1387:Eocene
1324:, the
1287:eroded
1278:mantle
1171:Canada
1118:Hawaii
1114:mantle
1081:basalt
1058:graben
758:Oregon
705:Oregon
344:massif
131:, the
127:, the
123:, the
89:, and
65:: the
49:, and
2167:from
2131:S2CID
2046:from
2003:from
1940:(PDF)
1908:(PDF)
1818:from
1775:from
1664:Idaho
1095:vents
604:Yukon
232:Gorda
51:soils
2082:ISBN
1961:link
1890:link
1639:sill
1585:and
1503:and
1491:The
1472:The
1461:and
1444:and
1417:and
1385:-to-
1373:and
1371:Kula
1342:The
1304:and
1120:and
1044:The
1027:and
1003:and
854:gas.
584:lava
570:The
543:The
484:The
348:clay
325:The
230:and
73:and
43:rock
37:The
2123:doi
1533:ice
1289:by
932:of
516:is
162:to
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2174:.
2143:^
2129:.
2121:.
2111:79
2109:.
2105:.
2055:.
2051:.
2026:^
2012:.
2008:.
1969:^
1957:}}
1953:{{
1916:29
1914:.
1910:.
1886:}}
1882:{{
1867:.
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1792:^
1782:.
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1188:.
1007:.
999:,
995:,
991:,
987:,
983:,
979:,
975:,
971:,
967:,
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868:BP
816:BP
806:BP
796:BP
778:BP
756:,
748:BP
738:BP
703:,
688:.
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