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87-626: Nazko Cone probably began erupting about 340,000 years ago and has grown steadily since then. Like all of the Anahim volcanoes, Nazko Cone has its origins in the Anahim hotspot —a plume of magma rising from deep in the Earth's mantle . The hotspot remains in a fixed position, while the North American Plate drifts over it at a rate of 2 to 3.3 centimetres per year. The upwelling of

174-523: A few kilometres from the volcano which could possibly start forest fires in the dry region. Any future eruption is likely to affect low flying air traffic only, since eruptions would likely be in the form of Hawaiian eruption - lava fountains that create small cinder cones and lava flows rather than voluminous ash clouds. Nazko Cone has been an intensively monitored volcano by the Geological Survey of Canada since October 10, 2007. One of

261-500: A few million years. The Anahim hotspot was stationed in a tectonically complex region of the Chilcotin Plateau between 3.9 and 1.4 million years ago. This complexity may have given rise to interactions of the hotspot with pre-existing fracture systems, such that magma rose along normal faults to create a 50-kilometre-long (31-mile) north–south trending chain of volcanoes. The Itcha Range developed directly over

348-452: A hotspot and a propagating crack controlled by stress fields related to large-scale plate tectonics of western North America. In 1981, Garry C. Rogers of the Geological Survey of Canada speculated that earthquake swarms at McNaughton Lake (now called Kinbasket Lake ) may be related to the Anahim hotspot. Rogers noted that if the seismicity is related to a hotspot the surface expression must be lagging 100 kilometres (62 miles) behind

435-491: A longer period of oblique convergence. Bathyal sediments , perhaps as young as 15 million years, were deposited within the rift zone during and after the rifting took place as the Anahim hotspot passed by. Starting about 10 million years ago, the Anahim hotspot began to pass under the Bella Coola – Ocean Falls region. This coincided with increased regional uplift of the south-central Coast Mountains. After

522-549: A number of specifications including kiln dried and grade stamped, and can be supplied in very long lengths to 60 feet. West coast mills are sophisticated in their processing of timbers, making lead times predictable and availability reliable. Paints adhere well to Douglas fir. Stains perform well on Douglas fir timbers with the mild caution that the natural color of this species varies and care must be taken to ensure uniformity of color. Pitch pockets that may ooze resin can be present in timbers that have not been kiln dried. Because of

609-591: A separate centre that most likely represents an area of lithospheric decompression melting caused by rifting along pre-existing crustal fractures . The Wells Gray-Clearwater volcanic field has since not been considered part of the Anahim Volcanic Belt and the Anahim hotspot is now believed to be in the area of Nazko Cone. The existence of an Anahim hotspot was supported in a detailed Bulletin of Volcanology report by Kuehn et al. (2015). This included new geochemical and geochronometric data for

696-478: A significant concentration of seismic activity within the Anahim Volcanic Belt. Vigorous degassing of carbon dioxide occurs from several vents in two bogs near Nazko Cone. These vents are in the form of small isolated travertine mounds on the bog surface. A mound with a partially submerged vent had been identified in 2013 with a steady flow of carbon dioxide. Several new vents with no travertine mound were actively releasing carbon dioxide gas in 2015. Analysis of

783-424: A unique tool in assessing and testing the motion of North America. Another hypothesis is that the Anahim hotspot is supplied by a miniplume. These mantle plumes have their roots in the upper mantle but they may later originate from the lower mantle. Arguments for an Anahim miniplume are centred on the existence of two small dike swarms at the western (hence oldest) end of the Anahim Volcanic Belt. This assumption

870-532: Is native to western North America and is also known as Douglas-fir , Douglas spruce , Oregon pine , and Columbian pine . There are three varieties: coast Douglas-fir ( P. menziesii var. menziesii ), Rocky Mountain Douglas-fir ( P. menziesii var. glauca ) and Mexican Douglas-fir ( P. menziesii var. lindleyana ). Despite its common names , it is not a true fir ( genus Abies ), spruce (genus Picea ), or pine (genus Pinus ). It

957-449: Is a continuous "rumble" which contrasts with the normal seismic activity of sudden shocks and is believed to be caused by the rapid movement of magma underground. Volcanic tremor normally indicates an imminent eruption, although it may also be caused by shallow intrusions of magma which do not reach the surface. Another important indicator of what is happening underground is the shape of the volcano. Tiltmeters measure very small changes in

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1044-633: Is a hypothesized hotspot in the Central Interior of British Columbia , Canada. It has been proposed as the candidate source for volcanism in the Anahim Volcanic Belt , a 300 kilometres (190 miles) long chain of volcanoes and other magmatic features that have undergone erosion. This chain extends from the community of Bella Bella in the west to near the small city of Quesnel in the east. While most volcanoes are created by geological activity at tectonic plate boundaries,

1131-455: Is a significant component. The red vole nests almost exclusively in the foliage of the trees, typically 2–50 metres (5–165 ft) above the ground, and its diet consists chiefly of Douglas-fir needles. Douglas-fir needles are generally poor browse for ungulates , although in the winter when other food sources are lacking it can become important, and black-tailed deer browse new seedlings and saplings in spring and summer. The spring diet of

1218-496: Is a unique wetland which appears to be saturated ash. What makes it unique is the fact that normally wetlands are saturated organic material such as peat moss . The wetland at Nazko Cone, however, is mixed organic and lava or ash, and the resultant ecosystem is quite unexpected. High heat flow in the Nazko Cone area is being evaluated as a potential source of geothermal heating. Anahim hotspot The Anahim hotspot

1305-432: Is also not a hemlock ; the genus name Pseudotsuga means "false hemlock". Douglas-firs are medium-size to extremely large evergreen trees, 20–100 metres (70–330 feet) tall (although only coast Douglas-firs , reach heights near 100 m) and commonly reach 2.4 m (8 ft) in diameter, although trees with diameters of almost 5 metres (16 feet) exist. The largest coast Douglas-firs regularly live over 500 years, with

1392-712: Is considered to be an invasive species, called a wilding conifer , and is subject to control measures. But is also one of the most common lumber trees used in forestry alongside Radiata pine with large plantations throughout the country. The species was introduced in the 1900s for its wood. Douglas-fir prefers acidic or neutral soils. However, it exhibits considerable morphological plasticity, and on drier sites P. menziesii var. menziesii will generate deeper taproots. Pseudotsuga menziesii var. glauca exhibits even greater plasticity, occurring in stands of interior temperate rainforest in British Columbia, as well as at

1479-516: Is extensively used in forestry management as a plantation tree for softwood timber . Douglas-fir is one of the world's best timber-producing species and yields more timber than any other species in North America, making the forestlands of western Oregon, Washington, and British Columbia the most productive on the continent. In 2011, Douglas-fir represented 34.2% of US lumber exports, to a total of 1.053 billion board-feet. Douglas fir timber

1566-843: Is found in the Klamath and California Coast Ranges as far south as the Santa Lucia Range , with a small stand as far south as the Purisima Hills in Santa Barbara County. One of the last remaining old growth stands of conifers is in the Mattole Watershed, and is under threat of logging. In the Sierra Nevada , it ranges as far south as the Yosemite region. It occurs from sea level along

1653-725: Is in turn based on the notion that giant dike swarms mark the arrival of deep-seated mantle plumes. In 1977, Jack Souther produced a synthesis of volcanism in the Canadian Cordillera and delineated several Neogene -to- Quaternary volcanic belts throughout British Columbia. One of these was the linear Anahim Volcanic Belt, which included the Wells Gray-Clearwater volcanic field at its eastern end. However, its origin had not yet been understood. In 1979, two volcano tectonic models had been proposed by Jack Souther, Mary Bevier and Richard Armstrong. This included

1740-416: Is likely to result in the creation of mafic cinder cones, with the latest such event having occurred with the eruption of Nazko Cone 7,200 years ago. However, eruptions of less mafic magma, typical of earlier activity of the Anahim hotspot, cannot be ruled out. Douglas fir The Douglas fir ( Pseudotsuga menziesii ) is an evergreen conifer species in the pine family, Pinaceae . It

1827-413: Is misleading since it is not a true fir, i.e., not a member of the genus Abies . For this reason, the name is often written as Douglas-fir (a name also used for the genus Pseudotsuga as a whole). The specific epithet menziesii is after Archibald Menzies , a Scottish physician and rival naturalist to David Douglas. Menzies first documented the tree on Vancouver Island in 1791. Colloquially,

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1914-555: Is more shade tolerant than some associated fire-dependent species, such as western larch and ponderosa pine, and often replaces these species further inland. Fungal diseases such as laminated root rot and shoestring root-rot can cause significant damage, and in plantation settings dominated by Douglas-fir monocultures may cause extreme damage to vast swathes of trees. Interplanting with resistant or nonhost species such as western redcedar and beaked hazelnut can reduce this risk. Other threats to Douglas-fir include red ring rot and

2001-710: Is set in a remote location accessed by a network of logging roads from Quesnel on Highway 97 . Because of this, the most immediate hazard relating to future eruptions is of local concern only. Although not heavily populated, the area is home to forestry operations and the small community of Nazko . The presence of burned wood within Nazko tephra suggests that this area is prone to forest fires caused by volcanic eruptions. Also, if an eruption column were to be produced, it would disrupt local air traffic. Volcanic ash reduces visibility and can cause jet engine failure, as well as damage to other aircraft systems. Renewed volcanism

2088-486: Is the Douglas-fir dwarf mistletoe ( Arceuthobium douglasii ). Epiphytes such as crustose lichens and mosses are common sights on Douglas-firs. As it is only moderately shade tolerant , undisturbed Douglas-fir stands in humid areas will eventually give way to later successional, more shade-tolerant associates such as the western redcedar and western hemlock—though this process may take a thousand years or more. It

2175-546: Is the most productive volcanically and features repeated eruptions of large volumes of predominately fluid peralkaline felsic magmas that become progressively more evolved. During this stage, a small summit caldera may form, as is the case for the Ilgachuz Range . After the shield stage has been completed, the post-shield stage succeeds. This stage of activity is characterized by small volumes of mafic lavas expressed as small cinder cones and capping flows. Dissection of

2262-416: Is used for timber frame construction and timber trusses using traditional joinery, veneer , and flooring due to its strength, hardness and durability. As of 2024, the only wooden ships still currently in use by the U.S. Navy in conventional naval operations are Avenger-class minesweepers , made of Douglas-fir. Douglas fir sees wide use in heavy timber structures, as its wood is strong, available in

2349-656: The Baldface Mountain and Satah Mountain volcanic fields , as well as for Nazko Cone. The obtained data indicated that volcanism in the two fields were contemporaneous with the adjacent Itcha Range shield volcano and that both volcanic fields agree with the vector of the North American plate motion over a hotspot in the British Columbia Interior. It was also noted that the trace and rare-earth element patterns of mafic lavas in

2436-693: The Bella Bella and Gale Passage dike swarms are prime examples of this phase of erosion. Rifting and crustal extension in Queen Charlotte Sound up to about 17 million years ago has been linked to the Early Miocene passage of the Anahim hotspot. Yorath and Chase (1981) proposed that subcrustal melting above the Anahim plume resulted in weakening of the regional crust, setting the stage for rift development. Later, widespread volcanism produced subaerial basalt and rhyolite flows in

2523-505: The Douglas-fir beetle . Many different Native American groups used the bark, resin, and needles to make herbal treatments for various diseases. Native Hawaiians built waʻa kaulua ( double-hulled canoes ) from coast Douglas-fir logs that had drifted ashore. The wood has historically been favored as firewood , especially from the coastal variety. In addition early settlers used Douglas fir for all forms of building construction, including floors, beams, and fine carving. The species

2610-585: The Geological Society of America , suggests that the Anahim hotspot might be supplied by a mantle plume from the upper mantle rather than a deep-seated plume proposed by Wilson. Tomographic imaging has since identified a low-velocity anomaly, indicative of an upwelling plume, that measures roughly 400 kilometres (250 miles) deep. This measurement, however, could be an underestimate as the anomaly might originate deeper inside Earth. Volcanism as early as 14.5 million years ago has been linked to

2697-484: The Hawaiian Islands . In 1963, Wilson proposed that small, long lasting, exceptionally hot areas of magma exist under Earth's surface; these heat centres create thermally active mantle plumes, which in turn sustain long-lasting volcanic activity. This intraplate volcanism builds peaks that rise above the surrounding landscape. Plate tectonics cause the local tectonic plate (in the case of the Anahim hotspot,

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2784-548: The Lynn Valley Tree and the Nooksack Giant . The leaves are flat, soft, linear needles 2–4 centimetres ( 3 ⁄ 4 – 1 + 1 ⁄ 2  in) long, generally resembling those of the firs, occurring singly rather than in fascicles ; they completely encircle the branches, which can be useful in recognizing the species. As the trees grow taller in denser forest, they lose their lower branches, such that

2871-530: The Miocene . Individual volcanoes drift southwest from the hotspot at a rate of about 2–3 centimetres (0.79–1.18 inches) per year with each successive volcanic centre spending about two million years actively attached to the plume. The oldest Anahim volcano, situated on the Central Coast of British Columbia, formed 14.5 million years ago. If any prior record in the form of seamounts existed off

2958-550: The Umpqua River in Oregon. It is most dominant in areas with a more frequent fire regime that suppresses less fire-resistant conifers. Douglas-fir seeds are an extremely important food source for small mammals such as moles , shrews , and chipmunks , which consume an estimated 65% of each annual seed crop. The Douglas squirrel harvests and hoards great quantities of Douglas-fir cones, and also consumes mature pollen cones,

3045-468: The blue grouse features Douglas-fir needles prominently. The leaves are also used by the woolly conifer aphid Adelges cooleyi ; this 0.5 mm-long sap -sucking insect is conspicuous on the undersides of the leaves by the small white "fluff spots" of protective wax that it produces. It is often present in large numbers, and can cause the foliage to turn yellowish from the damage it causes. Exceptionally, trees may be partially defoliated by it, but

3132-459: The carbon-13 isotope in the carbon dioxide gas emissions suggest a magmatic origin. This has led to the possibility of a volcanic geothermal system, the existence of which has been investigated by Geoscience BC as part of their Targeting Resources for Exploration and Knowledge project. The lack of hot springs and geothermal evidence on the surface suggest that the heat source of such a system would be very deep underground. The Anahim hotspot

3219-459: The Anahim Volcanic Belt are similar to ocean island basalts , providing more evidence for a hotspot. High-resolution local tomography indicates a possible lower-mantle plume and a pond of plume material is evidenced by a large low-velocity zone in the upper mantle. These low seismic velocity zones often indicate hotter and more buoyant mantle material. The low-velocity zone is flanked on both sides by high-velocity anomalies of variable amplitude. In

3306-447: The Anahim hotspot has its own unique life cycle of growth and erosion. Volcanic cones have their origins from tephra accumulating around vents during Strombolian eruptions . They are composed of trachyte, trachyandesite, basalt, phonolite, basanite and to a lesser extent phonotephrite. In contrast, lava domes are formed mainly by viscous trachytic magma that erupts effusively onto the surface and then piles up thick around vents. Considering

3393-408: The Anahim hotspot is about 500 kilometres (310 miles) from the nearest plate boundary. While studying the Anahim Volcanic Belt in 1979, Canadian geologists Mary Bevier, Richard Armstrong and Jack Souther used the hotspot theory to explain this zone of volcanism so far from regular conditions. The theory was first invented by Canadian geophysicist John Tuzo Wilson in 1963 to explain the formation of

3480-548: The Anahim hotspot is located hundreds of kilometres away from the nearest plate boundary. The hotspot was first proposed in the 1970s by three scientists who used John Tuzo Wilson 's classic hotspot theory. This theory proposes that a single, fixed mantle plume builds volcanoes that then, cut off from their source by the movement of the North American plate , become increasingly inactive and eventually erode over millions of years. A more recent theory, published in 2001 by

3567-477: The Anahim hotspot, with the latest eruption having taken place in the last 8,000 years. This volcanic activity has produced rocks that show a bimodal distribution in composition. While these rocks were being deposited, the hotspot coincided with periods of crustal extension and uplift . Activity in modern times has been limited to earthquakes and volcanic gas emissions. Tectonic plates generally focus deformation and volcanism at plate boundaries. However,

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3654-501: The Anahim magmas are analogous to regions of incipient continental rifting above a mantle plume. Over the last 14.5 million years, the Anahim hotspot has created at least 40 volcanoes. These centres comprise the Anahim Volcanic Belt, one of the six Neogene–Quaternary volcanic provinces in British Columbia. The Anahim Volcanic Belt can be organized into three groupings: the western section, which has been reduced to remnants of eruptive breccia, high-level plutons and dike swarms;

3741-604: The British Columbia Coast, this record would presumably have been subducted under North America with the Farallon /Juan de Fuca plates and lost. Therefore, it remains unknown if the hotspot existed in the Pacific Ocean prior to being located on the North American continent from ongoing plate motion. However, past geologic field mapping and geochemical studies suggest massive plutons could be present in

3828-462: The Juan de Fuca slab through the transition zone into the lower mantle. This has led to the conclusion that the Anahim hotspot is supplied by a mantle plume over slab edge flow. Isotopic studies of lead and strontium in Anahim lavas indicate the presence of suboceanic mantle under central British Columbia, which in turn corroborates the lack of a subducting slab under the Anahim Volcanic Belt since

3915-534: The Mexican border, becoming increasingly disjunct as latitude decreases and altitude increases. Mexican Douglas-fir ( P. lindleyana ), which ranges as far south as Oaxaca , is often considered a variety of P. menziesii . Fossils (wood, pollen) of Pseudotsuga are recorded from the Miocene and Pliocene of Europe ( Siebengebirge , Gleiwitz , Austria). It is also naturalised throughout Europe, Argentina and Chile (called Pino Oregón ). In New Zealand it

4002-411: The Nazko Cone was also a unique ecosystem. The vegetation included a complex of species. Very large old Douglas fir trees were common, growing in some of the more soil-like ash and lava . White spruce was surprisingly common, although severely stunted, whereas lodgepole pine was not. There were some shallow caves and hollows below the volcano. To the west, following the lava flow mentioned above,

4089-478: The North American plate margin. A unique characteristic of the felsic lava flows is that although they were high in silica content, the flows were overly fluid in nature. This is because the peralkaline content of these felsic lavas decreased the viscosity of the flows a minimum of 10–30 times over that of calc-alkaline felsic flows. Evidence for explosive volcanism exists in the form of pumice flows, bedded tuffs , intensely shattered basement rocks and

4176-429: The North American plate) to slowly slide over the hotspot, carrying its volcanoes with it without affecting the plume. Over hundreds of thousands of years, the magma supply for the volcano is slowly cut off, eventually going extinct. No longer active enough to overpower erosion, the volcano slowly erodes away. As the cycle continues, a new volcanic centre manifests and a volcanic peak arises anew. The process continues until

4263-503: The Satah Mountain volcanic field. Volcanic eruptions in the last 0.33 million years have been mainly basanitic and have occurred at the youngest eruptive centre, Nazko Cone. Basanites produced by these eruptions are significantly more undersaturated than basalts from older Anahim volcanoes in the west and may indicate an eastward shift toward a deeper or less depleted mantle source. The overall chemistry and mineralogy of

4350-411: The back half of a mouse, with two feet and a tail. The massive mega- genome of Douglas fir was sequenced in 2017 by the large PineRefSeq consortium, revealing a specialized photosynthetic apparatus in the light-harvesting complex of genes. The common name honors David Douglas , a Scottish botanist and collector who first reported the extraordinary nature and potential of the species. The common name

4437-425: The central section, which consists of predominantly shield volcanoes; and the eastern section, which comprises several small cinder cones and is the location of all modern volcanic activity. The Anahim volcanoes are grouped into three types: volcanic cones , shield volcanoes and lava domes . The shields are characterized by their large size (hundreds of kilometres in volume) and their symmetrical shape. They are

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4524-607: The coast to elevations of 1,500 m (4,900 ft) or higher, and inland in some cases up to 2,100 m (6,900 ft). Another variety exists further inland, Pseudotsuga menziesii var. glauca , the Rocky Mountain Douglas-fir or interior Douglas-fir. Interior Douglas-fir intergrades with coast Douglas-fir in the Cascades of northern Washington and southern British Columbia, and from there ranges northward to central British Columbia and southeastward to

4611-578: The cones are over 3 m deep and thin to less than a few centimetres only a few kilometres away, which suggests that the explosive eruptions at Nazko Cone were fairly small. However, the last eruption from Nazko Cone could have started forest fires , since there is charcoal inside the tephra layer. The volcano has been dormant since the 7200 BP eruption. On October 10, 2007, a small swarm of earthquakes appeared 20 kilometres west of Nazko Cone. Most of these earthquakes were magnitude 1.0 or less; some as strong as M 3.1 or 3.2 were centered 25 kilometres below

4698-539: The damage is rarely this severe. Among Lepidoptera , apart from some that feed on Pseudotsuga in general, the gelechiid moths Chionodes abella and C. periculella as well as the cone scale-eating tortrix moth Cydia illutana have been recorded specifically on P. menziesii . The inner bark is the primary winter food for the North American porcupine . Poriol is a flavanone, a type of flavonoid, produced by P. menziesii in reaction to infection by Poria weirii . A parasitic plant which uses P. menziesii

4785-900: The edge of semi-arid sagebrush steppe throughout much of its range, where it generates even deeper taproots still. The coast Douglas-fir variety is the dominant tree west of the Cascade Mountains in the Pacific Northwest . It occurs in nearly all forest types and competes well on most parent materials, aspects, and slopes. Adapted to a more moist, mild climate than the interior subspecies, it grows larger and faster than Rocky Mountain Douglas-fir. Associated trees include western hemlock , Sitka spruce , sugar pine , western white pine , ponderosa pine , grand fir , coast redwood , western redcedar , California incense-cedar , Lawson's cypress , tanoak , bigleaf maple and several others. Pure stands are also common, particularly north of

4872-427: The eruption of two different progressions of fluid lava flows , an older grey basalt overlain by a younger, darker black basalt. The passive eruptions were followed by a period of explosive eruptions . This explosive activity built three overlapping cinder cones near the end of the explosive phase of activity. The last phase of explosive activity spread tephra to the north and east of the cones. The deepest deposits near

4959-423: The foliage may start as high as 34 m (110 ft) off the ground. Douglas-firs in environments with more light may have branches much closer to the ground. The bark on young trees is thin, smooth, grey, and contains numerous resin blisters. On mature trees, usually exceeding 80 years, it is very thick and corky, growing up to 36 cm (14 in) thick with distinctive, deep vertical fissures caused by

5046-441: The generally small dimensions of these two volcano types, they are likely the products of episodic and short-lived activity. Larger structures such as Satah Mountain , Baldface Mountain and Mount Punkutlaenkut are exceptions. Once activity has ended, erosion eventually reduces the cones and domes into volcanic remnants such as lava plugs . Shield volcanoes undergo at least two stages of volcanic activity. The initial shield stage

5133-569: The gradual expansion of the growing tree. Some of the mature bark is brown, while other parts are lighter colored with a cork-like texture; these develop in multiple layers. This thick bark makes the Douglas-fir one of the most fire-resistant tree native to the Pacific Northwest. The female cones are pendulous, with persistent scales, unlike those of true firs. They have distinctive long, trifid (three-pointed) bracts which protrude prominently above each scale and are said to resemble

5220-553: The high content of coarse basement clasts in rhyolite breccias . Magma production of the Anahim hotspot has shifted from more felsic to more mafic compositions in the last 3.0 million years. For instance, much of the magma created between 3.0 and 0.33 million years ago was igneous phonolite , trachyte, trachyandesite , basalt and basanite ; the volcanoes built during this period are almost entirely made of these rock types. Other igneous rocks such as phonotephrite are present in smaller quantities; these occur in

5307-486: The hot magma creates volcanoes, and each individual volcano erupts for a few million years before the movement of the plate carries it away from the rising magma. The hotspot has existed for at least 13 million years, and the Anahim Volcanic Belt stretches almost 600 kilometres (400 mi) away from the hotspot. Currently, the hotspot lies under Nazko Cone, which is the youngest volcano in the Anahim Volcanic Belt. The eruptive cycle of Nazko Cone 7200 years ago started with

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5394-510: The hotspot and this is easily observable; the oldest rock on coastal British Columbia, that of the Gale Passage dike swarm , is about 14.5 million years old and deeply eroded, while the rock at Nazko Cone , the hotspot's present centre, is a comparatively young 0.34 million years of age or less. Radiocarbon dating of peat directly above and below a tephra layer extending 4 kilometres (2.5 miles) from Nazko Cone suggest that

5481-472: The hotspot reached the Chilcotin Plateau 8 million years ago, uplift had decreased. This suggests that the uplift could have been thermally driven by the Anahim hotspot, which thinned the lithosphere and caused changes in sub-crustal and surface heat flux . About 1 kilometre (0.62 miles) of uplift was achieved during the hotspot's time in the south-central Coast Mountains over a period of

5568-419: The inner bark, terminal shoots, and developing young needles. Mature or "old-growth" Douglas-fir forest is the primary habitat of the red tree vole ( Arborimus longicaudus ) and the spotted owl ( Strix occidentalis ). Home range requirements for breeding pairs of spotted owls are at least 400 hectares (4.0 km ; 990 acres) of old growth. Red tree voles may also be found in immature forests if Douglas-fir

5655-402: The interface when the warmer lower layer heats a portion of the cooler upper layer. This heated, buoyant and less- viscous portion of the upper layer would become less dense due to thermal expansion and rise towards the surface as a Rayleigh-Taylor instability . When the mantle plume reaches the base of the lithosphere , the plume heats it and produces melt. This magma then makes its way to

5742-593: The intersection whereas the Satah Mountain volcanic field developed along the more distal portions of the fracture system and away from the Itcha Range. A lack of extensive volcanic fields adjacent to the neighbouring Ilgachuz and Rainbow ranges might indicate an absence of fracture systems associated with those volcanoes. Volcanic eruptions are not known to have occurred from the Anahim hotspot in historical times. However, since 2007 there have been recorded volcano tectonic earthquakes and carbon dioxide emissions in

5829-528: The landward end of the rift. Such a plate boundary might have been similar to the Gulf of California  – San Andreas fault system in the U.S. state of California . This type of configuration need have existed for only a few million years to generate the 70 kilometres (43 miles) of opening in the rift. Alternatively, the Haida Gwaii block may have been only partially coupled to the offshore plate during

5916-455: The latest eruption occurred approximately 7,200 years ago. Geophysicists believe that hotspots originate at one or two major boundaries deep in the Earth, either a shallow interface in the lower mantle between an upper convecting layer and a lower non-convecting layer, or a deeper D″ ("D double-prime") layer , approximately 200 kilometres (120 miles) thick and immediately above the core-mantle boundary . A mantle plume would initiate at

6003-437: The mainland. The composition of the volcanoes' magma has changed significantly with time as they grow over the hotspot and migrate away. Volcanic activity 14.5 to 3.0 million years ago was predominately felsic , producing large volumes of rhyolite and trachyte lava. This can be explained by the presence of thick granitic structures under these volcanoes, which have been tectonically compressed from being near

6090-539: The mantle plume itself collapses. This cycle of growth and dormancy strings together volcanoes over millions of years, leaving a trail of volcanic mountains and intrusions extending from coastal British Columbia across the Coast Mountains into the Interior Plateau . According to Wilson's theory, the Anahim volcanoes should be progressively older and increasingly eroded the further they are from

6177-451: The most important tools is seismometry. About 5 seismometers were set up around Nazko Cone to enable scientists to measure the intensities and locations of hundreds of small earthquakes every day. Since then, there have been more than 1000 small earthquakes recorded. Earthquakes can begin to increase years before an eruption actually starts. Another type of seismic activity occurs in the hours preceding an eruption. So-called harmonic tremor

6264-639: The most prominent of the three volcano types, with the Rainbow Range being the highest at around 2,500 metres (8,200 feet) above sea level. Their outer slopes merge with older flat-lying basalt flows of the Chilcotin Group , which covers a large percentage of the Interior Plateau. The more abundant lava domes and volcanic cones are much smaller in size (less than one kilometre in volume). These comprise two extensive volcanic fields in

6351-442: The north, high-velocities may reflect the remains of batholithic roots that formed as a result of continuous subduction along the northern continental margin 150 to 50 million years ago. High velocities in the south represent the subducting Juan de Fuca slab . Centered near Nazko Cone, the low-velocity zone extends to a depth of approximately 400 kilometres (250 miles) . However, it may extend deeper southward beneath

6438-548: The offshore continental shelf. These suspected bodies are aligned with the northeast-trending Anahim Volcanic Belt, whose age progression suggests these suspected offshore plutons could be of Miocene age. An earlier displaced portion of the hotspot track might exist on Haida Gwaii as part of the Masset Formation . However, further analyses of Masset volcanic rocks are still required to determine if they are compositionally and istopically similar to alkalic lavas found on

6525-468: The oldest specimens living for over 1,300 years. Rocky Mountain Douglas-firs , found further to the east, are less long-lived, usually not exceeding 400 years in age. There are records of former coast Douglas-firs exceeding 120 metres (390 feet) in height, which if alive today would make it the tallest tree species on Earth. Particular historical specimens with heights exceeding 400 feet include

6612-487: The passage of the hotspot. An alternative theory proposed by Rogers is that if the Anahim hotspot is located under the Wells Gray-Clearwater area, the stress field surrounding the hotspot must precede it by approximately 100 kilometres (62 miles) . In 1987, Canadian volcanologist Catherine Hickson revealed that the Wells Gray-Clearwater volcanic field is not part of the Anahim Volcanic Belt, but rather

6699-486: The profile of the volcano, and sensitive equipment measures distances between points on the volcano. As magma fills the shallow reservoirs below the summit, the mountain inflates. Nazko Cone was staked for mining its cinder and scoria in the early 1990s by the Canadian Pumice Corporation , and has since been steadily reduced to produce red industrial aggregate for landscaping. Before mining,

6786-526: The region of the rift and along transcurrent faults that extend towards the northwest. Haida Gwaii was displaced approximately 70 kilometres (43 miles) to the north along a series of faults extending through Sandspit and Louscoone Islet. This period of rifting and crustal extension contributed to the formation of the Queen Charlotte Basin . While the rift was in development, a conservative plate boundary would have extended northwards from

6873-483: The shield by stream erosion is also apparent, resulting in the creation of deeply incised radial valleys . Prolonged erosion eventually removes most if not all traces of the volcanoes to expose their underlying solidified magma systems. Such systems can be 1 to 4 kilometres (0.62 to 2.49 miles) below the surface with rocks ranging from hypabyssal to plutonic. Exposure of the King Island Pluton and

6960-472: The species is also known simply as Doug fir or Douglas pine (although the latter common name may also refer to Pinus douglasiana ). Other names for this tree have included Oregon pine , British Columbian pine , Puget Sound pine , Douglas spruce , false hemlock , red fir , or red pine (although again red pine may refer to a different tree species, Pinus resinosa , and red fir may refer to Abies magnifica ). One Coast Salish name for

7047-556: The surface, indicating they originated within the lowermost crust. Analysis of seismic waves suggest that the earthquake swarm was caused by brittle failure and fracturing of rock at depth from magma intrusion. No volcanic eruption was likely as the number and size of the tremors were too small. Nevertheless, these earthquakes suggest that the Anahim hotspot is seismically active and that small magma movements are still possible. Although these earthquakes were too small to be felt, they generated substantial local interest as they represented

7134-498: The surface, where it is erupted as lava . Arguments for the validity of the hotspot theory generally centre on the steady age progression of Anahim volcanoes and nearby features: a similar eastward- younging spatiotemporal trend exists for the Yellowstone hotspot track 1,400 kilometres (870 miles) to the southeast. The presence of two hotspot tracks on the same continent and their general agreement between each other provides

7221-422: The surface. The cause of this seismic activity is believed to be the upwelling of magma because the area is not close to any faults or tectonic plate boundaries. Future eruptions from Nazko Cone are unlikely to cause many fatalities, due to the region's remoteness. There is active logging and ranching in the region, and people engaged in these activities are at some risk. Lava flows are likely to flow only

7308-493: The timber sizes available, stamped timber grading, and relatively short lead times, Douglas fir sees wide use in both public and residential projects. The species has ornamental value in large parks and gardens. It has been commonly used as a Christmas tree since the 1920s, and the trees are typically grown on plantations. The buds have been used to flavor eau de vie , a clear, colorless fruit brandy. Douglas-fir pine leaves can be used to make pine needle tea . They possess

7395-705: The tree, used in the Halkomelem language, is lá:yelhp . In the Lushootseed language, the tree is called čəbidac . Pseudotsuga menziesii var. menziesii , the coast Douglas-fir, grows in the coastal regions from west-central British Columbia southward to central California . In Oregon and Washington , its range is continuous from the eastern edge of the Cascades west to the Pacific Coast Ranges and Pacific Ocean. In California, it

7482-537: The vicinity of Nazko Cone. The lack of evidence for historic seismicity prior to 2007 suggests that the area is tectonically stable, making the Nechako Basin one of the most seismically inactive areas of British Columbia. From October 9, 2007, to May 15, 2008, a series of earthquakes measuring up to 2.9 magnitude occurred in the Nechako Basin some 20 kilometres (12 miles) west of Nazko Cone. Most of them occurred 25 to 31 kilometres (16 to 19 miles) below

7569-612: The vicinity of the Itcha Range. Although many Anahim volcanoes are surrounded by Chilcotin Group basalt flows, the exact nature of their relationship is unknown. It is unlikely the Anahim volcanoes ever were a source area for the Chilcotin basalts as they have distinct transitional geochemistries. The Chilcotin Group is interpreted to be related to back-arc extension behind the Cascadia subduction zone . Each volcano type produced by

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