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126-569: The shield is associated with an extensive group of related volcanoes called the Northern Cordilleran Volcanic Province (NCVP). This forms part of the much larger Ring of Fire , which surrounds most of the Pacific Ocean basin. Geologic studies have shown that Maitland was a comparatively short-lived volcano. It had volcanic activity for less than a million years, a time span unique from other massive NCVP shields. The volcano

252-429: A glacial armor . Ice can not only erode mountains but also protect them from erosion. Depending on glacier regime, even steep alpine lands can be preserved through time with the help of ice. Scientists have proved this theory by sampling eight summits of northwestern Svalbard using Be10 and Al26, showing that northwestern Svalbard transformed from a glacier-erosion state under relatively mild glacial maxima temperature, to

378-426: A considerable depth. A gully is distinguished from a rill based on a critical cross-sectional area of at least one square foot, i.e. the size of a channel that can no longer be erased via normal tillage operations. Extreme gully erosion can progress to formation of badlands . These form under conditions of high relief on easily eroded bedrock in climates favorable to erosion. Conditions or disturbances that limit

504-408: A fall in sea level, can produce a distinctive landform called a raised beach . Chemical erosion is the loss of matter in a landscape in the form of solutes . Chemical erosion is usually calculated from the solutes found in streams. Anders Rapp pioneered the study of chemical erosion in his work about Kärkevagge published in 1960. Formation of sinkholes and other features of karst topography

630-409: A few millimetres, or for thousands of kilometres. Agents of erosion include rainfall ; bedrock wear in rivers ; coastal erosion by the sea and waves ; glacial plucking , abrasion , and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows . The rates at which such processes act control how fast

756-479: A glacier-armor state occupied by cold-based, protective ice during much colder glacial maxima temperatures as the Quaternary ice age progressed. These processes, combined with erosion and transport by the water network beneath the glacier, leave behind glacial landforms such as moraines , drumlins , ground moraine (till), glaciokarst , kames, kame deltas, moulins, and glacial erratics in their wake, typically at

882-464: A homogeneous bedrock erosion pattern, curved channel cross-section beneath the ice is created. Though the glacier continues to incise vertically, the shape of the channel beneath the ice eventually remain constant, reaching a U-shaped parabolic steady-state shape as we now see in glaciated valleys . Scientists also provide a numerical estimate of the time required for the ultimate formation of a steady-shaped U-shaped valley —approximately 100,000 years. In

1008-423: A large river can remove enough sediments to produce a river anticline , as isostatic rebound raises rock beds unburdened by erosion of overlying beds. Shoreline erosion, which occurs on both exposed and sheltered coasts, primarily occurs through the action of currents and waves but sea level (tidal) change can also play a role. Hydraulic action takes place when the air in a joint is suddenly compressed by

1134-487: A mountain mass similar to the Himalaya into an almost-flat peneplain if there are no significant sea-level changes . Erosion of mountains massifs can create a pattern of equally high summits called summit accordance . It has been argued that extension during post-orogenic collapse is a more effective mechanism of lowering the height of orogenic mountains than erosion. Examples of heavily eroded mountain ranges include

1260-410: A result, they speculated that the remnants were not the remains of a continuous blanket of basaltic lava but fragments of individual flows poured out on a surface of considerable relief. These lava flow remnants were subsequently mapped in greater detail by Jack Souther in 1972 and later by Hu Gabrielse and Howard Tipper in 1984. Maitland Volcano is the namesake for Maitland Creek, a tributary of

1386-606: A result, volcanism in the Northern Cordilleran Volcanic Province is also not related to back-arc basin volcanism. When the stored energy is suddenly released by slippage across the fault at irregular intervals, it can create very large earthquakes , such as the magnitude  8.1 Queen Charlotte Islands earthquake of 1949 . As these far-field forces stretch the North American crust, the near surface rocks fracture along steeply dipping faults parallel to

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1512-516: A sequence of north-trending faults were mapped that seem to represent young rifting events parallel with the southwestern boundary of the Northern Cordilleran Volcanic Province. These rift-related faults might have been active as recently as five million years ago and they might have connections with adjacent Miocene and younger volcanic activity in the southern part of the Northern Cordilleran Volcanic Province. In addition, brittle faults with similar north-trending directions might enlarge as far north as

1638-454: A shallower depth than one from a zone with a reduced geothermal gradient that also records a temperature of 900 °C (1,650 °F). Further evidence that indicate lithospheric thickening beneath the middle portion of Stikinia include the increased profusion of cognate inclusion and plagioclase megacrysts in volcanic rocks from the southern portion of the volcanic province, which might be evidence of magma ponding and magma crystallization in

1764-432: A surface is eroded. Typically, physical erosion proceeds the fastest on steeply sloping surfaces, and rates may also be sensitive to some climatically controlled properties including amounts of water supplied (e.g., by rain), storminess, wind speed, wave fetch , or atmospheric temperature (especially for some ice-related processes). Feedbacks are also possible between rates of erosion and the amount of eroded material that

1890-501: A wave closing the entrance of the joint. This then cracks it. Wave pounding is when the sheer energy of the wave hitting the cliff or rock breaks pieces off. Abrasion or corrasion is caused by waves launching sea load at the cliff. It is the most effective and rapid form of shoreline erosion (not to be confused with corrosion ). Corrosion is the dissolving of rock by carbonic acid in sea water. Limestone cliffs are particularly vulnerable to this kind of erosion. Attrition

2016-412: A weak bedrock (containing material more erodible than the surrounding rocks) erosion pattern, on the contrary, the amount of over deepening is limited because ice velocities and erosion rates are reduced. Glaciers can also cause pieces of bedrock to crack off in the process of plucking. In ice thrusting, the glacier freezes to its bed, then as it surges forward, it moves large sheets of frozen sediment at

2142-425: Is a broader name, to encompass a broader geographic area, in which the most recent volcanism has a similar character (mainly alkaline, mafic volcanic rocks), a similar age range ( Miocene to Holocene ), and a similar tectonic setting (transtension). Erosion Erosion is the action of surface processes (such as water flow or wind ) that removes soil , rock , or dissolved material from one location on

2268-554: Is a sequence of late Paleozoic and Mesozoic aged volcanic, plutonic and sedimentary rocks interpreted to have been created in an island arc environment that were later placed along a pre-existing continental margin . The Cache Creek Terrane is believed to have formed widely in a pre-existing oceanic basin . It comprises late Paleozoic to Mesozoic aged oceanic melange and abyssal peridotites intruded by younger granitic intrusions. The Yukon–Tanana and Cassiar terranes consist of shifted sedimentary and metamorphic rocks that were derived from

2394-537: Is already carried by, for example, a river or glacier. The transport of eroded materials from their original location is followed by deposition, which is arrival and emplacement of material at a new location. While erosion is a natural process, human activities have increased by 10–40 times the rate at which soil erosion is occurring globally. At agriculture sites in the Appalachian Mountains , intensive farming practices have caused erosion at up to 100 times

2520-490: Is also more prone to mudslides, landslides, and other forms of gravitational erosion processes. Tectonic processes control rates and distributions of erosion at the Earth's surface. If the tectonic action causes part of the Earth's surface (e.g., a mountain range) to be raised or lowered relative to surrounding areas, this must necessarily change the gradient of the land surface. Because erosion rates are almost always sensitive to

2646-484: Is an example of extreme chemical erosion. Glaciers erode predominantly by three different processes: abrasion/scouring, plucking , and ice thrusting. In an abrasion process, debris in the basal ice scrapes along the bed, polishing and gouging the underlying rocks, similar to sandpaper on wood. Scientists have shown that, in addition to the role of temperature played in valley-deepening, other glaciological processes, such as erosion also control cross-valley variations. In

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2772-409: Is distinguished from changes on the bed of the watercourse, which is referred to as scour . Erosion and changes in the form of river banks may be measured by inserting metal rods into the bank and marking the position of the bank surface along the rods at different times. Thermal erosion is the result of melting and weakening permafrost due to moving water. It can occur both along rivers and at

2898-532: Is independent of lithosphere structure. In contrast, clear glassy plagioclase megacrysts are found largely at the southern end of the Northern Cordilleran Volcanic Province and largely within the boundaries of the Stikinia terrane. This suggests the plagioclase megacrysts have a source that is sensitive to the Earth's lithosphere, including contamination or magma ponding. Megacrysts made of plagioclase and clinopyroxene regionally show significant evidence of reaction with

3024-591: Is known to have produced at least four types of lava, namely alkali basalt , hawaiite , trachyte and trachybasalt . These have been studied by scientists since the 1950s. Maitland Volcano was one of the most voluminous shield volcanoes in the Northern Cordilleran Volcanic Province along with Heart Peaks , Level Mountain and the Mount Edziza volcanic complex . Its structure was about 50 km (31 mi) long and 40 km (25 mi) wide, covering an area of at least 1,000 km (390 sq mi) . This

3150-405: Is of two primary varieties: deflation , where the wind picks up and carries away loose particles; and abrasion , where surfaces are worn down as they are struck by airborne particles carried by wind. Deflation is divided into three categories: (1) surface creep , where larger, heavier particles slide or roll along the ground; (2) saltation , where particles are lifted a short height into

3276-445: Is relatively small compared to other large NCVP shield volcanoes. This supports field evidence for rapid, relatively uninterrupted growth of the volcanic edifice. The suspension of Maitland volcanism corresponds with changes in regional tectonics about four million years ago. After Maitland Volcano became extinct, prolonged erosion destroyed the volcanic edifice. The reason why Maitland eroded away while its neighbour, Edziza, did not

3402-526: Is similar in size to the Mount Edziza complex approximately 40 km (25 mi) west of Maitland Volcano. Like most shields, Maitland consisted of several basaltic lava flows which have low viscosity. This gave the volcano its massive profile and consequently Maitland might have had a broad lava plateau like other large NCVP shields. Like other Northern Cordilleran volcanoes , Maitland Volcano had its origins in continental rifting —a long rupture in

3528-404: Is sparse and soil is dry (and so is more erodible). Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion. In some areas of

3654-457: Is the main climatic factor governing soil erosion by water. The relationship is particularly strong if heavy rainfall occurs at times when, or in locations where, the soil's surface is not well protected by vegetation . This might be during periods when agricultural activities leave the soil bare, or in semi-arid regions where vegetation is naturally sparse. Wind erosion requires strong winds, particularly during times of drought when vegetation

3780-641: Is the most recently defined volcanic province in the Western Cordillera . It has formed due to extensional cracking of the North American continent—similar to other on-land extensional volcanic zones, including the Basin and Range Province and the East African Rift . Although taking its name from the Western Cordillera, this term is a geologic grouping rather than a geographic one. The southmost part of

3906-595: Is twofold. With the cessation of volcanic activity, Maitland Volcano was unable to protect itself from erosion by providing a cover of younger lavas on top of the older shield. Another factor is that Maitland's basement was built entirely of soft, friable sedimentary rocks of the Bowser Lake Group . Such rocks are more vulnerable to erosion than igneous rocks . The Bowser Lake Group sedimentary rocks are shale , sandstone , conglomerate and siltstone , which were deposited in marine and non-marine environments during

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4032-400: Is where particles/sea load carried by the waves are worn down as they hit each other and the cliffs. This then makes the material easier to wash away. The material ends up as shingle and sand. Another significant source of erosion, particularly on carbonate coastlines, is boring, scraping and grinding of organisms, a process termed bioerosion . Sediment is transported along the coast in

4158-609: The Cascadia subduction zone , defined by the eastward extension of the northern edge of the subducting Juan de Fuca Plate . These two zones divide the Northern Cordilleran Volcanic Province from modern volcanic zones further south, including the broad Chilcotin Plateau , the east–west trending Anahim Volcanic Belt and the monogenetic Wells Gray-Clearwater volcanic field in the British Columbia Interior . The eastern boundary of

4284-468: The Earth's crust and then transports it to another location where it is deposited . Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution . Eroded sediment or solutes may be transported just

4410-626: The Fort Selkirk Volcanic Field in central Yukon, Prindle Volcano in easternmost Alaska and at Castle Rock and the Iskut River in northern British Columbia. Felsic intrusive xenoliths are a lot more common and usually originate from adjacent granitic intrusions, including those that form the Coast Mountains. More than 14 volcanic zones throughout the Northern Cordilleran Volcanic Province comprise xenoliths that originated from

4536-658: The Great Plains , it is estimated that soil loss due to wind erosion can be as much as 6100 times greater in drought years than in wet years. Mass wasting or mass movement is the downward and outward movement of rock and sediments on a sloped surface, mainly due to the force of gravity . Mass wasting is an important part of the erosional process and is often the first stage in the breakdown and transport of weathered materials in mountainous areas. It moves material from higher elevations to lower elevations where other eroding agents such as streams and glaciers can then pick up

4662-606: The Jurassic and Cretaceous periods. Intervening valleys, deeply incised into the Jurassic shale and sandstone, are as much as 600 m (2,000 ft) below the base of the now deeply eroded Maitland shield volcano. Most of the rugged topography of the Klappan Range formed after Maitland Volcano was built. Erosional remnants of lava flows from Maitland Volcano are present as scattered, cliff-bounded cappings on higher mountains of

4788-562: The Klappan River that flows from the eroded basement of Maitland Volcano. Maitland Creek was in turn named on May 6, 1975 for William John Maitland of Vancouver who served as flight lieutenant in the Royal Canadian Air Force during World War II . Maitland was killed in action on December 16, 1943 while serving with 208 squadron on operations over Europe; he was 22 years old. In 1990, Canadian volcanologist Jack Souther gave

4914-498: The Nahlin Plateau . These four volcanoes have volumes of more than 15 km (3.6 cu mi), the largest and oldest which is Level Mountain with an area of 1,800 km (690 sq mi) and a volume of more than 860 km (210 cu mi). Apart from the large volcanoes, several smaller volcanoes exist throughout the Northern Cordilleran Volcanic Province, including cinder cones which are widespread throughout

5040-662: The Stikine Volcanic Belt , is a geologic province defined by the occurrence of Miocene to Holocene volcanoes in the Pacific Northwest of North America . This belt of volcanoes extends roughly north-northwest from northwestern British Columbia and the Alaska Panhandle through Yukon to the Southeast Fairbanks Census Area of far eastern Alaska , in a corridor hundreds of kilometres wide. It

5166-700: The Timanides of Northern Russia. Erosion of this orogen has produced sediments that are now found in the East European Platform , including the Cambrian Sablya Formation near Lake Ladoga . Studies of these sediments indicate that it is likely that the erosion of the orogen began in the Cambrian and then intensified in the Ordovician . If the erosion rate exceeds soil formation , erosion destroys

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5292-416: The accumulation zone above the glacial equilibrium line altitude), which causes increased rates of erosion of the mountain, decreasing mass faster than isostatic rebound can add to the mountain. This provides a good example of a negative feedback loop . Ongoing research is showing that while glaciers tend to decrease mountain size, in some areas, glaciers can actually reduce the rate of erosion, acting as

5418-461: The boundary between the Earth's crust and mantle is shallowest beneath the northern portion of the Northern Cordilleran Volcanic Province. Therefore, the temperature ranges for the northernmost xenolith series is about one-half the temperature range found in xenoliths at the southern portion of the volcanic province. Megacrysts , crystals or grains that are considerably larger than the encircling matrix , are commonly found in lava flows throughout

5544-405: The impact of a falling raindrop creates a small crater in the soil , ejecting soil particles. The distance these soil particles travel can be as much as 0.6 m (2.0 ft) vertically and 1.5 m (4.9 ft) horizontally on level ground. If the soil is saturated , or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs. If

5670-489: The last glacial period have been eroded and overridden by glacial ice, affording a less distinctive form to these older landforms. For example, lava beds at least a million years old in central Yukon contain unconsolidated glacial deposits that were deposited when glacial ice rode on top of the lava flows comprising the lava beds. Subvolcanic intrusions in the Northern Cordilleran Volcanic Province are exposed in areas of high relief. This includes volcanic plugs found at

5796-455: The lower crust and mantle . Because tectonic processes are driven by gradients in the stress field developed in the crust, this unloading can in turn cause tectonic or isostatic uplift in the region. In some cases, it has been hypothesised that these twin feedbacks can act to localize and enhance zones of very rapid exhumation of deep crustal rocks beneath places on the Earth's surface with extremely high erosion rates, for example, beneath

5922-407: The surface runoff which may result from rainfall, produces four main types of soil erosion : splash erosion , sheet erosion , rill erosion , and gully erosion . Splash erosion is generally seen as the first and least severe stage in the soil erosion process, which is followed by sheet erosion, then rill erosion and finally gully erosion (the most severe of the four). In splash erosion ,

6048-592: The 18th century. Lava Fork at the British Columbia-Alaska border is influenced by lava flows from a recent volcanic eruption that later collapsed into underlying lava tubes after the lava solidified. Sections of these collapsed lava tubes now form volcanic pits. Extensive areas of nearly flat-lying lava flows throughout the Northern Cordilleran Volcanic Province can cover areas of at least 100 km (39 sq mi) and are generally composed of highly-fluid basaltic lava. However, lava plains that pre-date

6174-499: The 21st century, a strong link has been drawn between the increase in storm frequency with an increase in sediment load in rivers and reservoirs, highlighting the impacts climate change can have on erosion. Vegetation acts as an interface between the atmosphere and the soil. It increases the permeability of the soil to rainwater, thus decreasing runoff. It shelters the soil from winds, which results in decreased wind erosion, as well as advantageous changes in microclimate. The roots of

6300-689: The Earth's crust where the lithosphere is being pulled apart. This incipient rifting formed as a result of the Pacific Plate sliding northward along the Queen Charlotte Fault , on its way to the Aleutian Trench . As the continental crust stretched, the near surface rocks fractured along steeply dipping cracks parallel to the rift known as faults . Basaltic magma rose along these fractures to create effusive eruptions . The rift zone has existed for at least 14.9 million years and has created

6426-430: The Earth's upper mantle under the Northern Cordilleran Volcanic Province is the existence of a slab window. However, not much of a noticeable evidence linking the production of magma in the upper mantle to a possible tectonic system has been stated. The existence of a fault next to the western flank of the Mount Edziza volcanic complex is normally considered to be the prime structural evidence for continental rifting in

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6552-646: The Earth's mantle and are located mainly at the Yukon–Tanana Terrane, the Cache Creek Terrane and at volcanoes occupying the Paleozoic and Mesozoic Stikinia terrane. They consist of lherzolite, harzburgite , wehrlite , dunite , websterite and garnet composed pyroxenite . The highest and lowest temperatures recorded by mantle xenoliths increase to the south and decrease to the north. Mantle xenoliths at Prindle Volcano in easternmost Alaska record

6678-659: The Geological Survey of Canada in 1991 as a group of volcanic deposits centered around the Stikine River in northwestern British Columbia. As more mapping and dating of volcanic deposits was completed in the Western Cordillera, the Stikine Volcanic Belt was expanded to include volcanic deposits further and further from the geographic area associated with the name Stikine. In part for this reason, scientists Ben Edwards and James Russell redefined this area of volcanism as

6804-561: The Klappan Range. These flat-lying lava caps are up to 400 m (1,300 ft) thick and contain as much as 20 separate lava flow units, each commonly 2 to 20 m (6.6 to 65.6 ft) thick. Aphyric to slightly feldspar - phyric basalt is the primary volcanic rock , although greenish-grey trachybasalt and pale green trachyte form the uppermost flows of thick sections. The highest remnant of Maitland Volcano has an elevation of 2,514 m (8,248 ft) . A cluster of 14  volcanic plugs are exposed that were originally under

6930-609: The Lakelse Hot Springs. Hot springs are also present in Iskut River Hot Springs Provincial Park and Choquette Hot Springs Provincial Park in northwestern British Columbia. Xenoliths , rock fragments that become enveloped in a larger igneous rock , are widespread in the Northern Cordilleran Volcanic Province. Xenoliths that originated in the Earth's crust include rich metamorphic rocks and felsic intrusive rocks. Granulite xenoliths exist mainly at

7056-575: The Mount Edziza volcanic complex, Level Mountain, Hoodoo Mountain and in the Atlin and Maitland areas. Volcanic plugs in the Atlin and Maitland areas consist of olivine nephelinite and basanite magmas. Minor plugs made of gabbroic and granitic magma are associated with volcanic stratigraphy at the Mount Edziza volcanic complex and Level Mountain. The bedrock of the Northern Cordilleran Volcanic Province consists of four large terranes , known as Stikinia, Cache Creek , Yukon–Tanana and Cassiar . Stikinia

7182-598: The NCVP has more, and larger, volcanoes than does the rest of the NCVP; further north it is less clearly delineated, describing a large arch that sways westward through central Yukon. At least four large volcanoes are grouped with the Northern Cordilleran Volcanic Province, including Hoodoo Mountain in the Boundary Ranges , the Mount Edziza volcanic complex on the Tahltan Highland , and Level Mountain and Heart Peaks on

7308-414: The North American continent. The southern boundary of the Northern Cordilleran Volcanic Province is parallel with southwestern Stikinia and is characterized by separate volcanic vents and erosional remains of lavas south of the small community of Stewart . The southern boundary of the Northern Cordilleran Volcanic Province also parallels with a gap in modern volcanism and the supposed northern boundary of

7434-415: The Northern Cordilleran Volcanic Province display trace element abundances and isotopic compositions that are logical with an asthenospheric source like those for average oceanic island basalt and for alkaline basalts younger than five million years in the rift-related Basin and Range Province of southwestern United States and northwestern Mexico . One hypothesized explanation for oceanic island basalt in

7560-464: The Northern Cordilleran Volcanic Province has its origins in continental rifting —an area where the Earth's crust and lithosphere is being pulled apart. This differs from other portions of the Pacific Ring of Fire as it consists largely of volcanic arcs formed by subducting oceanic crust at oceanic trenches along continental margins circling the Pacific Ocean . The continental crust at

7686-462: The Northern Cordilleran Volcanic Province is being stretched at a rate of about 2 cm (1 in) per year. This incipient rifting formed as a result of the Pacific Plate sliding northward along the Queen Charlotte Fault , on its way to the Aleutian Trench , which extends along the southern coastline of Alaska and the adjacent waters off the southern coast of the Kamchatka Peninsula . As

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7812-540: The Northern Cordilleran Volcanic Province is bounded by the Cassiar Terrane and is adjoined by a cluster of volcanic plugs in central British Columbia. The northern and western boundaries are adjoined by the Yukon–Tanana and Cache Creek terranes where there lies volcanics in eastern Alaska and weathered remains of lava flows just north and west of Dawson City in west-central Yukon. The Tintina and Denali faults are

7938-523: The Northern Cordilleran Volcanic Province is commonly interpreted to be part of a gap in the Pacific Ring of Fire between the Cascade Volcanic Arc further south and the Aleutian Arc further north. But the Northern Cordilleran Volcanic Province is recognized to include over 100 independent volcanoes that have been active in the past 1.8 million years. At least three of them have erupted in

8064-416: The Northern Cordilleran Volcanic Province is magmas are mainly alkaline , it includes highly alkaline and peralkaline rock types, the main spatial-temporal pattern of volcanism is in the middle of the volcanic province followed by movement to the south, north and possibly northeast, heat flow in the Northern Cordilleran Volcanic Province is high, seismic activity is largely absent in the volcanic province and

8190-440: The Northern Cordilleran Volcanic Province, indicating magmatic heat is present under the Northern Cordilleran Volcanic Province. They are formed if water percolates deeply through the crust and heats up from the primal magmatic heat under the surface. After the groundwater is heated, the heated groundwater rises to the surface as a hot spring. In some cases, the heated groundwater may rise along extensional faults related to rifting in

8316-501: The Northern Cordilleran Volcanic Province, volcanism throughout the past 1.6 million years is possibly due to repetitive upper mantle upwelling and adjacent transtension throughout the Queen Charlotte Fault, accommodated partly by numerous east–west trending fault zones that extend all through the Northern Cordilleran Volcanic Province. The volcanics comprising the Northern Cordilleran Volcanic Province are consistent with

8442-419: The Northern Cordilleran Volcanic Province, would aid the formation of high-level reservoirs of capable size and thermal activity to maintain long-lived fractionation. The variety of different temperature ranges from xenoliths throughout the Northern Cordilleran Volcanic Province indicate that a narrow lithosphere lies under the northern portion of the volcanic province and a more dense lithosphere lies under

8568-538: The Northern Cordilleran Volcanic Province. As a geographic descriptor, application of the name Stikine to volcanic rocks exposed along the Yukon River seems a bit odd and confusing. As well, a much older group of totally unrelated volcanic rocks comprise the Stikine Assemblage, which also mainly occurs within the geographic area informally referred to as Stikine Country . The Northern Cordilleran Volcanic Province

8694-417: The Northern Cordilleran Volcanic Province. However, more recent mapping and seismic studies in the Coast Mountains have documented the presence of brittle rift-related faults southwest of the small community of Stewart in northwestern British Columbia. But these faults were in a matter of dispute in 1997 by geologists, stating these faults were last active between 20 and five million years ago. In 1999,

8820-438: The Northern Cordilleran Volcanic Province. They consist of three different groups, including kaersutitic amphibole megacrysts, clinopyroxene megacrysts and plagioclase megacrysts. Megacrysts made of kaersutite are known to be found mainly at Llangorse Mountain in northern British Columbia. Black glassy clinopyroxene megacrysts are widespread throughout the Northern Cordilleran Volcanic Province, suggesting their creation

8946-518: The Northern Cordilleran Volcanic Province. The Lakelse Hot Springs near Lakelse Lake Provincial Park in northern British Columbia is interpreted to be one such example. With a temperature of 89 °C (192 °F), the springs are the hottest in Canada. It is also possible the magma associated with the Nass Valley eruption 250 years ago to the north rose along the same north trending fault lines fueling

9072-580: The Northern Cordilleran Volcanic Province. This geologic province forms part of the Ring of Fire, an area where large numbers of earthquakes and volcanic eruptions occur along the Pacific Ocean. Maitland's volcanic history is poorly known since only isolated remnants of the volcano remain. What is known, however, is that it formed during a pulse of NCVP magmatism that began with the eruption of Edziza about seven million years ago. The eruption rate of this period

9198-462: The Queen Charlotte Fault 10 million years ago produced consequent strain throughout the northern portion of the Western Cordillera, resulting in crustal thinning and decompression melting of oceanic island basalt-like mantle to create alkaline volcanism. Several plate motion models indicate a rebound to net compression throughout the Queen Charlotte Fault sometime after four million years ago. Although extensive rifting has not yet been recognized in

9324-631: The Tintina Fault likely occurred during two pulses in the Mid-Cretaceous and early Cenozoic periods, respectively, with the latter probably occurring during the Eocene epoch. Since the Cretaceous, the Tintina Fault has offset 450 km (280 mi) of the surface, although some evidence suggest as much as 1,200 km (750 mi) of offset. The offset caused the Northern Cordilleran Volcanic Province and

9450-566: The Tintina Fault, strike-slip movement along the Denali Fault has offset at least 370 km (230 mi) of the surface. The fault separates mountains of the Insular Belt from mountains east of the fault. Tectonic events in the Insular Belt are also related to movement along the Denali Fault. The term Stikine Volcanic Belt was originally defined by Jack Souther and Christopher Yorath of

9576-433: The air, and bounce and saltate across the surface of the soil; and (3) suspension , where very small and light particles are lifted into the air by the wind, and are often carried for long distances. Saltation is responsible for the majority (50–70%) of wind erosion, followed by suspension (30–40%), and then surface creep (5–25%). Wind erosion is much more severe in arid areas and during times of drought. For example, in

9702-632: The associated magma, including sieve-textured cores and random, resorbed and embayed outer margins wherever they are located. Lava tubes are widespread in the Northern Cordilleran Volcanic Province, and are typically basaltic in composition. At Level Mountain, lava tubes reach diameters of 1 m (3.3 ft) to 2 m (6.6 ft). These owed their origin to highly fluid lavas with temperatures of at least 1,200 °C (2,190 °F). In Nisga'a Memorial Lava Beds Provincial Park of northwestern British Columbia, lava tubes are present that were formed during one of Canada's most recent volcanic eruptions in

9828-463: The base along with the glacier. This method produced some of the many thousands of lake basins that dot the edge of the Canadian Shield . Differences in the height of mountain ranges are not only being the result tectonic forces, such as rock uplift, but also local climate variations. Scientists use global analysis of topography to show that glacial erosion controls the maximum height of mountains, as

9954-506: The boundaries ( half-grabens ). Grabens are indicative of tensional forces and crustal stretching. Two major north-trending faults hundreds of kilometres long extend along the Northern Cordilleran Volcanic Province. These two rock fractures, known as the Tintina and Denali fault systems, have been tectonically active since the Cretaceous period as strike-slip faults . The Denali fault to

10080-502: The central part of Maitland Volcano. These form steep-sided, isolated monoliths that reach heights of 150 m (490 ft) above the surrounding eroded terrain . They are circular to elliptical in shape, ranging in diameter from 100 to 250 m (330 to 820 ft) . The plugs represent the principal feeders through which the Maitland lavas reached the surface. Red oxidized pyroclastic blocks surround some plugs protruding through

10206-645: The central part of the basaltic shield. Magmatism at Maitland continued until about 4.6 million years ago when the volcano went extinct . Volcanic activity at Maitland Volcano was consistent with extensional stresses across the northern Canadian Cordillera that began around 10 million years ago as a result of new plate motions between the Pacific and North American plates. This contributed to lithospheric thinning and decompression melting of OIB -like mantle to produce alkaline Neogene magmatism. The time span of 600,000 years for magmatism at Maitland Volcano

10332-512: The coast. Rapid river channel migration observed in the Lena River of Siberia is due to thermal erosion, as these portions of the banks are composed of permafrost-cemented non-cohesive materials. Much of this erosion occurs as the weakened banks fail in large slumps. Thermal erosion also affects the Arctic coast , where wave action and near-shore temperatures combine to undercut permafrost bluffs along

10458-409: The coastline. Where there is a bend in the coastline, quite often a buildup of eroded material occurs forming a long narrow bank (a spit ). Armoured beaches and submerged offshore sandbanks may also protect parts of a coastline from erosion. Over the years, as the shoals gradually shift, the erosion may be redirected to attack different parts of the shore. Erosion of a coastal surface, followed by

10584-411: The direction of the prevailing current ( longshore drift ). When the upcurrent supply of sediment is less than the amount being carried away, erosion occurs. When the upcurrent amount of sediment is greater, sand or gravel banks will tend to form as a result of deposition . These banks may slowly migrate along the coast in the direction of the longshore drift, alternately protecting and exposing parts of

10710-405: The extremely steep terrain of Nanga Parbat in the western Himalayas . Such a place has been called a " tectonic aneurysm ". Human land development, in forms including agricultural and urban development, is considered a significant factor in erosion and sediment transport , which aggravate food insecurity . In Taiwan, increases in sediment load in the northern, central, and southern regions of

10836-536: The fault next to the western flank of the Mount Edziza volcanic complex. These tectonic events might have helped form the structure the Northern Cordilleran Volcanic Province. Subduction beside the northern portion of the Western Cordillera deceased between 43 and 40 million years ago. This finally caused the formation of a slab window under the northern portion of the Western Cordillera 10 million years ago, supporting an entrance to relatively undepleted upper mantle. A switch in relative plate motions at

10962-575: The flood regions result from glacial Lake Missoula , which created the channeled scablands in the Columbia Basin region of eastern Washington . Wind erosion is a major geomorphological force, especially in arid and semi-arid regions. It is also a major source of land degradation, evaporation, desertification, harmful airborne dust, and crop damage—especially after being increased far above natural rates by human activities such as deforestation , urbanization , and agriculture . Wind erosion

11088-417: The growth of protective vegetation ( rhexistasy ) are a key element of badland formation. Valley or stream erosion occurs with continued water flow along a linear feature. The erosion is both downward , deepening the valley , and headward , extending the valley into the hillside, creating head cuts and steep banks. In the earliest stage of stream erosion, the erosive activity is dominantly vertical,

11214-425: The informal name Maitland volcanics for the remaining lava flows and volcanic plugs of Maitland Volcano. Evenchick et al. (2005) proposed Maitland Volcanics as a formal name for these volcanic rocks. 57°24′N 129°42′W  /  57.4°N 129.7°W  / 57.4; -129.7 Northern Cordilleran Volcanic Province The Northern Cordilleran Volcanic Province ( NCVP ), formerly known as

11340-411: The island can be tracked with the timeline of development for each region throughout the 20th century. The intentional removal of soil and rock by humans is a form of erosion that has been named lisasion . Mountain ranges take millions of years to erode to the degree they effectively cease to exist. Scholars Pitman and Golovchenko estimate that it takes probably more than 450 million years to erode

11466-606: The largest fault zones associated with the Northern Cordilleran Volcanic Province rift zone, with all volcanism occurring west of the Tintina Fault and east of the Denali Fault. Physiographically, the Tintina Fault forms the Northern Rocky Mountain Trench and the Tintina Trench , which is the northern extension of the Northern Rocky Mountain Trench. The fastest rates of strike-slip movement along

11592-483: The largest period of volcanism correlates with an interval of net extension between the Pacific and North American plates. A range of more heavily alkaline rock types not commonly found in the Western Cordillera are regionally widespread in the Northern Cordilleran Volcanic Province. These include nephelinite , basanite and peralkaline phonolite , trachyte , and comendite lavas. The most magnesium oxide -rich nephelinites, basanites and alkaline basalts all through

11718-424: The lithosphere before a volcanic eruption, and the restricted existence of petrologically evolved rock types in the southern half of the Northern Cordilleran Volcanic Province. If the developed magmas originated from fractionation of mafic magmas, fractionation associated with lithospheric contamination, or entirely from melting of the associated lithosphere, their existence suggests more dense lithosphere lies under

11844-409: The local slope (see above), this will change the rates of erosion in the uplifted area. Active tectonics also brings fresh, unweathered rock towards the surface, where it is exposed to the action of erosion. However, erosion can also affect tectonic processes. The removal by erosion of large amounts of rock from a particular region, and its deposition elsewhere, can result in a lightening of the load on

11970-418: The material and move it to even lower elevations. Mass-wasting processes are always occurring continuously on all slopes; some mass-wasting processes act very slowly; others occur very suddenly, often with disastrous results. Any perceptible down-slope movement of rock or sediment is often referred to in general terms as a landslide . However, landslides can be classified in a much more detailed way that reflects

12096-407: The material has begun to slide downhill. In some cases, the slump is caused by water beneath the slope weakening it. In many cases it is simply the result of poor engineering along highways where it is a regular occurrence. Surface creep is the slow movement of soil and rock debris by gravity which is usually not perceptible except through extended observation. However, the term can also describe

12222-438: The mechanisms responsible for the movement and the velocity at which the movement occurs. One of the visible topographical manifestations of a very slow form of such activity is a scree slope. Slumping happens on steep hillsides, occurring along distinct fracture zones, often within materials like clay that, once released, may move quite rapidly downhill. They will often show a spoon-shaped isostatic depression , in which

12348-560: The minimum temperature of 860 °C (1,580 °F) and mantle xenoliths from the Fort Selkirk Volcanic Field in central Yukon record the minimum temperature range from 960 to 1,050 °C (1,760 to 1,920 °F). At Castle Rock in northern British Columbia, mantle xenoliths record the maximum temperature of 1,260 °C (2,300 °F), as well as the maximum temperature range from 1,000 to 1,260 °C (1,830 to 2,300 °F). The minimum xenolith temperatures indicate that

12474-484: The morphologic impact of glaciations on active orogens, by both influencing their height, and by altering the patterns of erosion during subsequent glacial periods via a link between rock uplift and valley cross-sectional shape. At extremely high flows, kolks , or vortices are formed by large volumes of rapidly rushing water. Kolks cause extreme local erosion, plucking bedrock and creating pothole-type geographical features called rock-cut basins . Examples can be seen in

12600-404: The most erosion occurs during times of flood when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes: suspended abrasive particles, pebbles , and boulders can also act erosively as they traverse a surface, in a process known as traction . Bank erosion is the wearing away of the banks of a stream or river. This

12726-531: The natural rate of erosion in the region. Excessive (or accelerated) erosion causes both "on-site" and "off-site" problems. On-site impacts include decreases in agricultural productivity and (on natural landscapes ) ecological collapse , both because of loss of the nutrient-rich upper soil layers . In some cases, this leads to desertification . Off-site effects include sedimentation of waterways and eutrophication of water bodies , as well as sediment-related damage to roads and houses. Water and wind erosion are

12852-434: The nutrient-rich upper soil layers . In some cases, the eventual result is desertification . Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses. Water and wind erosion are the two primary causes of land degradation ; combined, they are responsible for about 84% of the global extent of degraded land , making excessive erosion one of

12978-411: The order of a few centimetres (about an inch) or less and along-channel slopes may be quite steep. This means that rills exhibit hydraulic physics very different from water flowing through the deeper, wider channels of streams and rivers. Gully erosion occurs when runoff water accumulates and rapidly flows in narrow channels during or immediately after heavy rains or melting snow, removing soil to

13104-400: The past 360 years, making it the most active volcanic area in Canada. Nevertheless, the dispersed population within the volcanic zone has witnessed few eruptions due to remoteness and the infrequent volcanic activity. The Northern Cordilleran Volcanic Province has been a zone of active volcanism since it began to form 20 million years ago. Unlike other parts of the Pacific Ring of Fire,

13230-556: The plants bind the soil together, and interweave with other roots, forming a more solid mass that is less susceptible to both water and wind erosion. The removal of vegetation increases the rate of surface erosion. The topography of the land determines the velocity at which surface runoff will flow, which in turn determines the erosivity of the runoff. Longer, steeper slopes (especially those without adequate vegetative cover) are more susceptible to very high rates of erosion during heavy rains than shorter, less steep slopes. Steeper terrain

13356-413: The relief between mountain peaks and the snow line are generally confined to altitudes less than 1500 m. The erosion caused by glaciers worldwide erodes mountains so effectively that the term glacial buzzsaw has become widely used, which describes the limiting effect of glaciers on the height of mountain ranges. As mountains grow higher, they generally allow for more glacial activity (especially in

13482-526: The remaining lava flows. These probably formed not far below the surface where eruption was accompanied by vent-clearing explosions. The remains of Maitland Volcano were first mapped and described by the Geological Survey of Canada in 1956 as part of Operation Stikine. They recognized the volcanic rocks capping the Klappan Range as remnants of once-extensive lava flows but noted the remnants may differ in elevation by 305 m (1,001 ft) or more. As

13608-414: The rift zone. Hot magma rises between these fractures to create passive or effusive eruptions . Volcanoes within the Northern Cordilleran Volcanic Province are located along short northerly trending segments which in the northern part of the volcanic province are unmistakenably involved with north-trending rift structures, including synvolcanic grabens and grabens with one major fault line along only one of

13734-563: The rifting environment. Alkaline basalt, lesser hawaiite and basanite magmas from effusive eruptions create the massive shield volcanoes and small cinder cones throughout the volcanic province, several of which comprise lherzolite magma. Felsic magmas from more viscous eruptions create the massive central volcanoes and largely consist of trachyte, pantellerite and comendite lavas. These felsic volcanics are understood to have been created by fractionation of mainly alkali basalt magma in crustal reservoirs. An area of continental rifting, such as

13860-828: The rolling of dislodged soil particles 0.5 to 1.0 mm (0.02 to 0.04 in) in diameter by wind along the soil surface. On the continental slope , erosion of the ocean floor to create channels and submarine canyons can result from the rapid downslope flow of sediment gravity flows , bodies of sediment-laden water that move rapidly downslope as turbidity currents . Where erosion by turbidity currents creates oversteepened slopes it can also trigger underwater landslides and debris flows . Turbidity currents can erode channels and canyons into substrates ranging from recently deposited unconsolidated sediments to hard crystalline bedrock. Almost all continental slopes and deep ocean basins display such channels and canyons resulting from sediment gravity flows and submarine canyons act as conduits for

13986-515: The runoff has sufficient flow energy , it will transport loosened soil particles ( sediment ) down the slope. Sheet erosion is the transport of loosened soil particles by overland flow. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are typically of

14112-532: The shoreline and cause them to fail. Annual erosion rates along a 100-kilometre (62-mile) segment of the Beaufort Sea shoreline averaged 5.6 metres (18 feet) per year from 1955 to 2002. Most river erosion happens nearer to the mouth of a river. On a river bend, the longest least sharp side has slower moving water. Here deposits build up. On the narrowest sharpest side of the bend, there is faster moving water so this side tends to erode away mostly. Rapid erosion by

14238-593: The soil. Lower rates of erosion can prevent the formation of soil features that take time to develop. Inceptisols develop on eroded landscapes that, if stable, would have supported the formation of more developed Alfisols . While erosion of soils is a natural process, human activities have increased by 10-40 times the rate at which erosion occurs globally. Excessive (or accelerated) erosion causes both "on-site" and "off-site" problems. On-site impacts include decreases in agricultural productivity and (on natural landscapes ) ecological collapse , both because of loss of

14364-526: The southern portion of the Northern Cordilleran Volcanic Province. In the Llangorse section of the Atlin Volcanic Field in northwestern British Columbia, a suite of xenoliths confines the thickness of the Northern Cordilleran Volcanic Province mantle lithosphere to as thin as 18 km (11 mi) and a thickness no more than 39 km (24 mi). Analysis of recent data related to earthquakes in

14490-404: The southern portion of the volcanic province. This indication is further provided if the geothermal gradient inside the lithosphere under the northern portion of the Northern Cordilleran Volcanic Province is greater than that in the southern portion of the province. A greater geothermal gradient would indicate that a xenolith recording a temperature of 900 °C (1,650 °F) was collected from

14616-533: The southwestern portion of the volcanic province indicates that the crust under Stikinia, which comprises the bedrock underlying a large number of volcanoes in the southern portion of the Northern Cordilleran Volcanic Province, is also more dense than the crust under the nearby Coast Plutonic Complex, which consists of a broad belt of granitic and dioritic intrusive rocks that collectively represent more than 140 million years of nearly continuous subduction-related magmatism. Hot springs are present throughout

14742-433: The terminus or during glacier retreat . The best-developed glacial valley morphology appears to be restricted to landscapes with low rock uplift rates (less than or equal to 2mm per year) and high relief, leading to long-turnover times. Where rock uplift rates exceed 2mm per year, glacial valley morphology has generally been significantly modified in postglacial time. Interplay of glacial erosion and tectonic forcing governs

14868-481: The terrains of which the volcanic province occupies to move northwards. In the context of plate tectonics, strip-slip movement of the Tintina Fault is also related to strike-slip movement along the San Andreas Fault and other extensional or strike-slip fault systems of western North America. To the west, the Denali Fault is the source of minor earthquakes that extend along the length of the fault. In contrast to

14994-409: The transfer of sediment from the continents and shallow marine environments to the deep sea. Turbidites , which are the sedimentary deposits resulting from turbidity currents, comprise some of the thickest and largest sedimentary sequences on Earth, indicating that the associated erosional processes must also have played a prominent role in Earth's history. The amount and intensity of precipitation

15120-563: The two primary causes of land degradation ; combined, they are responsible for about 84% of the global extent of degraded land, making excessive erosion one of the most significant environmental problems worldwide. Intensive agriculture , deforestation , roads , anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. However, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Rainfall , and

15246-427: The valleys have a typical V-shaped cross-section and the stream gradient is relatively steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain. The stream gradient becomes nearly flat, and lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far

15372-475: The volcanic zone. Most of these small cones have been sites of only one volcanic eruption; this is in contrast to the larger volcanoes throughout the volcanic zone, which have had more than one volcanic eruption throughout their history. The Northern Cordilleran Volcanic Province is part of an area of intensive earthquake and volcanic activity around the Pacific Ocean called the Pacific Ring of Fire . However,

15498-510: The west and the Tintina fault to the east are nearly 2,000 km (1,200 mi) long, extending from northern British Columbia to central Alaska. Other mechanisms suggested for triggering volcanism in the Northern Cordilleran Volcanic Province include mantle plumes , deglaciation and slab windows , although continental rifting is the most accurate mechanism for activating volcanism in the volcanic zone. Further evidence for continental rifting in

15624-550: The world (e.g. western Europe ), runoff and erosion result from relatively low intensities of stratiform rainfall falling onto the previously saturated soil. In such situations, rainfall amount rather than intensity is the main factor determining the severity of soil erosion by water. According to the climate change projections, erosivity will increase significantly in Europe and soil erosion may increase by 13–22.5% by 2050 In Taiwan , where typhoon frequency increased significantly in

15750-491: The world (e.g. the mid-western US ), rainfall intensity is the primary determinant of erosivity (for a definition of erosivity check, ) with higher intensity rainfall generally resulting in more soil erosion by water. The size and velocity of rain drops is also an important factor. Larger and higher-velocity rain drops have greater kinetic energy , and thus their impact will displace soil particles by larger distances than smaller, slower-moving rain drops. In other regions of

15876-459: Was much greater than what is observed for the Northern Cordilleran Volcanic Province today. Following the onset of activity at Edziza, Maitland volcanism commenced 5.2 million years ago with the outpouring of alkali basalt and hawaiite lava on a broad, late Tertiary , low-relief surface. This resulted in the creation of a broad shield volcano. Subsequent volcanic activity created a complex edifice of trachyte and trachybasalt that formerly overlain

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