Level Mountain

Coordinates: 58°28′43″N 131°26′14″W / 58.47861°N 131.43722°W / 58.47861; -131.43722
Source: Wikipedia, the free encyclopedia.

Level Mountain
An overhead view of vegetated terrain with two very large, rocky mountains near the crest of a mountain range to the southwest.
Satellite image of Level Mountain (middle-right) and Heart Peaks (upper-left corner). This image is approximately 80 km (50 mi) east–west.
Highest point
PeakMeszah Peak[1][2]
Elevation2,164 m (7,100 ft)[1][2]
ListingMountains of British Columbia
Coordinates58°28′43″N 131°26′14″W / 58.47861°N 131.43722°W / 58.47861; -131.43722[1][3]
Dimensions
Length70 km (43 mi)[4]
Width45 km (28 mi)[4]
Area1,800 km2 (690 sq mi)[5]
Volume860 km3 (210 cu mi)[5]
Geography
Level Mountain is located in British Columbia
Level Mountain
Level Mountain
Location in British Columbia
Country
spatter cones, tuyas (overlying features)[9]
Age of rockLess than 15 million years old[10]
Type of rockAlkali basalt, ankaramite, trachyte, rhyolite, phonolite[11]
Volcanic regionNorthern Cordilleran Province[12]
Last eruptionUnknown[6]

Level Mountain is a large

volcanic complex in the Northern Interior of British Columbia, Canada. It is located 50 kilometres (31 miles) north-northwest of Telegraph Creek and 60 kilometres (37 miles) west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,164 metres (7,100 feet), it is the second-highest of four large complexes in an extensive north–south trending volcanic region. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 metres (3,600 feet) tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower, broader half of Level Mountain consists of a shield-like structure while its upper half has a more steep, jagged profile. Its broad summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the mountain. Meszah Peak
is the only named peak in the Level Mountain Range.

The mountain began forming about 15 million years ago and has experienced volcanism up until geologically recent times. There have been four stages of activity throughout the long volcanic history of Level Mountain. The first stage commenced 14.9 million years ago with the eruption of voluminous lava flows; these created a large shield volcano. The second stage began 7.1 million years ago to form a structurally complicated stratovolcano located centrally atop the shield. A series of lava domes was established during the third stage, which began 4.5 million years ago. This was followed by the fourth and final stage with the eruption of lava flows and small volcanic cones in the last 2.5 million years. A wide range of rock types were produced during these stages, namely ankaramites, alkali basalts, trachybasalts, mugearites, hawaiites, phonolites, trachytes and rhyolites. Alkali basalts and ankaramites are the most voluminous and form most of Level Mountain. The remaining rock types are less extensive and are largely restricted to the central region of the volcanic complex. Several types of volcanic eruptions produced these rocks.

Level Mountain lies in one of many

caribou being the most abundant. A trading post was established at Level Mountain in the 1890s, followed by geological studies of the mountain from the 1920s onwards. This remote area of Cassiar Land District has a relatively dry environment compared to the Coast Mountains
in the west. Due to its remoteness, Level Mountain can only be accessed by air or by trekking great distances on foot. The closest communities are more than 30 kilometres (19 miles) away from the mountain.

Geography and geomorphology

Structure

Level Mountain has a volume of 860 cubic kilometres (210 cubic miles) and an area of 1,800 square kilometres (690 square miles), although at least one estimate of its areal extent is as much as 3,000 square kilometres (1,200 square miles).[4][5] Because of its great extent Level Mountain can be seen from outer space. This, coupled with snow and elevation, helps define the geology of the region.[5] Level Mountain dominates the Nahlin Plateau, a subdivision of the larger Stikine Plateau.[2][13]

Level Mountain comprises two principal components: a voluminous basal shield volcano and an overlying eroded stratovolcano.

lava plateau on which local streams flow.[4][12] The south and west sides of the plateau are marked by a well-defined but dissected escarpment. In contrast, the north and east plateau boundaries are less clear.[16] V-shaped stream canyons occur along the lava plateau margin, exposing a section of Tertiary basalts along the Grand Canyon of the Stikine.[17]

From an elevation of 1,400 metres (4,600 feet) onwards the overlying stratovolcano is dominant.[9] Ridges and peaks prevail at an elevation of 1,520 metres (4,990 feet) and comprise the Level Mountain Range.[16][17] These rise more steeply to 1,980 metres (6,500 feet), eventually reaching the highest point of 2,164 metres (7,100 feet) at Meszah Peak.[1][2][6][16] Therefore, when viewed from a distance, Level Mountain appears unusually flat except for a number of black peaks on its summit which have the appearance of enormous volcanic cones.[18]

Biogeography

Level Mountain is in the

alpine vegetation can be found.[21] Although alpine vegetation of the Stikine Plateau Ecosection can be lush and grass-rich above the tree line, wetlands and muskegs are the dominant ecosystems on Level Mountain.[20]

The Stikine Plateau Ecosection is one of seven ecosections comprising the

altai fescue covers the upper slopes but barren rock is abundant at higher elevations. A cold, dry boreal mountain climate characterizes this ecoregion.[23]

Plants

A group of small green-leaved, brown-stemmed trees in a grassy environment.
A pair of bog birch trees at Cedar Bog, Ohio. Such trees are present at Level Mountain.

Level Mountain is characterized by three biophysical zones. The first zone, below an elevation of 1,200 metres (3,900 feet), is predominated by vegetation of the Pinaceae and Betulaceae families. Lodgepole pine is associated with communities of kinnikinnick, bog birch, Altai fescue and moss. Mature white spruce and lodgepole pine forests dominate north of Level Mountain where bog birch occurs in river valley bottoms.[24]

The second biophysical zone lies between elevations of 1,200 and 1,540 metres (3,940 and 5,050 feet).

wildfires and are now limited only to the northern flank of Level Mountain.[26]

The third biophysical zone consists largely of an

moss campion, Arctic bluegrass and alpine lichens and mosses.[26]

Animals

The area contains a caribou herd that is part of a larger population extending west of the

ptarmigans, moose, long-tailed ducks and stone sheep.[4]

Soils

A variety of soil types with differing physical properties are found at Level Mountain. Shallow, coarse, textured and steep to strongly sloping soils dominate peaks of the Level Mountain Range and owe their origin to weathering of volcanic rocks. These well-drained soils are strongly

xeric in nature and show little or no horizon development. The gently undulating alpine portions of Level Mountain have been affected by cryoturbation, resulting in patterned ground in which coarse material has been separated from each other as patches or stripes. Surface horizons are strongly to very strongly acidic, becoming medium to slightly acidic approximately 50 centimetres (20 inches) in depth.[28] At lower elevations, soils develop on fluvioglacial deposits. Many of these fluvioglacial materials contain a high percentage of fine materials while the soils which have developed from them contain a subsurface horizon enriched by clay accumulation. Very poorly-drained organic soils are extensive on the southern portion of the lava plateau.[24]

Climate

The climate of Level Mountain is influenced by the presence of the Coast Mountains to the west, which disrupt the flow of the prevailing westerly winds. This disruption causes the winds to drop most of their moisture onto the western slopes of the Coast Mountains before reaching the Nahlin Plateau, casting a rain shadow over Level Mountain. Because the mountain has a gently sloping and flat profile, it has subtle differences in climate, particularly at the low to upper-mid elevations. Therefore, a relatively homogeneous climate extends over Level Mountain; only gradual temperature and precipitation gradients occur altitudinally.[13] As a result, the mountain lacks a wide diversity of local climates for large mammals.[29]

Travel from high to low elevations below 1,700 metres (5,600 feet) in the winter can be difficult for some mammals due to the accumulation of snow. Above 1,700 metres (5,600 feet), exposure to local winds is improved and ridges of snow are cleared on steeper slopes.[29] Wind speeds increase with elevation but the distribution of wind over the area is fairly uniform.[13] Level Mountain experiences relatively light snowfall unlike the Coast Mountains.[5]

During the late May and early June calving season, winds predominate from a southerly quadrant. Calm conditions are infrequent and average monthly wind speeds are on the order of 3 to 4 metres (9.8 to 13.1 feet) per second. At an elevation of 1,370 metres (4,490 feet), there is a 15–20% chance that precipitation will occur as snow; that probability increases with altitude. Mixed rain and snow are common at that time of the year. Reduced air drainage, coupled with clear calm nights, lowers minimum temperatures in the summer, reducing the frost-free period.[13]

Drainage

tributaries
that flow adjacent to the mountain.

The southern and eastern sides of Level Mountain are drained by streams within the

tributaries draining the southern side of Level Mountain.[31] The first tributary is the Little Tahltan River which flows to the southeast.[31][32] Bear Creek, the second tributary, flows to the south north of Glenora.[31][33] The third tributary is Beatty Creek which flows to the south north of Telegraph Creek.[31][34] Middle Creek, the fourth tributary, flows to the south near Beatty Creek.[31][35] It contains one named tributary, Riley Creek, which flows to the southwest.[31][36] The fifth named Tahltan River tributary draining the southern side of Level Mountain is Hartz Creek which flows to the south.[31][37] To the east, the Tuya River gathers two named tributaries draining the eastern side of Level Mountain.[31] The first tributary is the Little Tuya River which flows to the southeast.[31][38] It contains one named tributary, Mansfield Creek, which flows to the east.[31][39] The second named Tuya River tributary draining the eastern side of Level Mountain is Classy Creek which flows to the southeast.[31][40]

The northern and western sides of Level Mountain are drained by streams within the Nahlin River watershed.[30] To the west, the Dudidontu River flows to the northwest and gathers one named tributary draining the western side of Level Mountain.[31][41] This tributary, Kakuchuya Creek, flows to the north and gathers Matsatu Creek which flows to the northwest from the western side of Level Mountain where it has cut a large steep-sided gorge into the western escarpment.[31][42][43][44] The Koshin River flows to the north from the western side of Level Mountain and gathers two named tributaries.[31][45] These two tributaries, Lost Creek and Kaha Creek, also drain the western side of Level Mountain and flow to the northwest and west, respectively.[31][46][47] The only named stream draining the northern side of Level Mountain is Megatushon Creek which flows to the north.[31][48]

The southwestern side of Level Mountain is drained by streams within the Sheslay River watershed.[30] Egnell Creek is the only named stream in this watershed draining Level Mountain.[31] It flows southwest into the mouth of the Hackett River just above the junction with the Shesley River.[49]

Glaciology

Intense glaciation has taken place at Level Mountain in the last 5.33 million years, as shown by the presence of strongly developed

latest glacial period ended approximately 12,000 years ago.[50] Several U-shaped valleys have been carved into Level Mountain by radially directed alpine glaciers.[17] They serve as a radial drainage for Kakuchuya Creek, Beatty Creek, Lost Creek, Kaha Creek, the Dudidontu River and the Little Tahltan River.[16] The Kakuchuya and Beatty creek valleys have been eroded to a level below that of the plateau surface.[16]

stone striping, occur on Level Mountain at elevations greater than 1,250 metres (4,100 feet). Cryoturbation takes place mainly on flat and gently sloping areas while stone striping happens primarily on gently sloping areas adjacent to peaks of the Level Mountain Range. Some of the steeper slopes of the Level Mountain Range are confined to nivation[a] and solifluction.[b] Snow avalanches are limited only to the Level Mountain Range and the steepest slopes.[16]

Geology

Background

Level Mountain is part of the

peralkaline[c] phonolite, trachyte and comendite are locally abundant. These rocks were deposited by volcanic eruptions from 20 million years ago to as recently as a few hundred years ago. The cause of volcanic activity in the Northern Cordilleran Volcanic Province is thought to be due to rifting of the North American Cordillera driven by changes in relative plate motion between the North American and Pacific plates.[55]

Level Mountain is part of a subdivision of the NCVP called the Stikine Subprovince. This subprovince, confined to the Stikine region of northwestern British Columbia, consists of three other volcanic complexes: Heart Peaks, Hoodoo Mountain and Mount Edziza. The four complexes differ petrologically and/or volumetrically from the rest of the NCVP. Heart Peaks, Level Mountain and Mount Edziza are the largest NCVP centres by volume, the latter two of which have experienced volcanism for a much longer timespan than any other NCVP centre. Level Mountain, Hoodoo Mountain and Mount Edziza are the only NCVP centres that contain volcanic rocks of both mafic[d] and intermediate to felsic[e] composition.[57] The highest of the four complexes is Mount Edziza at 2,786 metres (9,140 feet), followed by Level Mountain at 2,164 metres (7,100 feet), Heart Peaks at 2,012 metres (6,601 feet) and Hoodoo Mountain at 1,850 metres (6,070 feet).[6][58][59][60]

Composition

A diagram explaining the geologic structure of a large volcano.
Geologic map of Level Mountain showing the basal shield volcano and the overlying stratovolcano

Several rock types with varying chemical compositions make up Level Mountain. Ankaramites and alkali basalts are the main volcanic rocks comprising the basal shield. Alkali basalts form

welded tuffs,[g] pitchstones, volcanic plugs, laccoliths[h] and flows. Trachybasalts are in the form of two textural types: phenocryst-rich lava flows and fragmental flow agglomerates.[i] Phonolites are vesicular and pumiceous[j] in nature, although phonolites with trachytic[k] texture are also present. Trachytes and peralkaline trachytes are the main volcanic rocks in the Level Mountain Range. Rhyolites are in the form of stubby lava flows and domes. Comendites appear to have erupted more fluidly, forming lava tubes.[67]

Basement and faulting

The

hanging wall of this thrust fault and are intensely cleaved, particularly near the sole of the thrust.[70] The other planar fracture, Nahlin, is an east-dipping thrust fault extending several hundred kilometres from northern British Columbia into southern Yukon.[71]

Tectonic uplift

Extensive tectonic uplift occurred at Level Mountain and elsewhere on the Stikine Plateau during the Neogene period.[2][17] This resulted in dissection of the plateau surface by stream erosion which varies greatly across the region.[2] The youthful V-shaped gorges along the lava plateau margin of Level Mountain are signs of continuing uplift, which may in part be caused by doming of the mountain during volcanism.[17][50] Several outcrops of alkali basalt south of Kennicott Lake and the Tahltan River are comparable in age to the Level Mountain shield volcano and may represent erosional remnants of this structure.[50]

Volcanic history

Level Mountain is the largest eruptive centre of the MEVC with respect to both volume and area covered.

upper mantle.[17]

More than 20 eruptive centres are present on the summit and flanks of Level Mountain.

pillow basalts and volcano-glacial tuff breccias.[17] It is possible that geothermal outputs at Level Mountain had an influence on dynamics of past ice sheets much like the modern Grímsvötn caldera is an important heat source beneath Vatnajökull in Iceland.[50] However, like other large volcanic centres in the NCVP, much of Level Mountain was formed prior to glaciation.[16] Hiatuses of up to a million years or more can be expected between periods of volcanic activity at Level Mountain.[78]

Mafic shield-building stage

A diagram explaining the distribution of rocks forming a large, oval-shaped volcano
Geologic map of Level Mountain showing eruptive products and eruptive centres

The mafic shield-building stage 14.9 to 6.9 million years ago began with the eruption of thin mafic lava flows over an

pāhoehoe flows characterized the fluid and effusive nature of volcanism during this stage.[17]

Lava flows of the mafic shield-building stage comprise four sub-horizontal units. Initial volcanism produced a 53-metre-thick (174-foot) sequence of columnar-jointed alkali basalt flows and altered grey-green vesicular basalts which form the lowest unit. Subsequent activity deposited the overlying second 107-metre-thick (351-foot) unit. This comprises up to seven 7.6-metre-thick (25-foot) columnar cooling units of alkali basalt separated by buff-weathered vesicular lava flows. Renewed volcanism deposited a 76-metre-thick (249-foot) sequence of massive ankaramite lava flows over the second unit. These lava flows, comprising the third unit, are spheroidally weathered.[p] The mafic shield-building stage culminated with the emplacement of the fourth and highest unit. Eight to ten sequences of columnar-jointed alkali basalt flows comprise this unit and have a total thickness of 122 metres (400 feet).[81] All four sub-horizontal units were deposited over a timespan of eight million years.[5]

Bimodal stratovolcano stage

A second stage of volcanic activity 7.1 to 5.3 million years ago produced peralkaline,

ash flow tuffs.[83] Peralkaline felsic lava flows reached 7 kilometres (4.3 miles) long and 3 to 8 metres (9.8 to 26.2 feet) thick.[17] The eruptive products of the bimodal stratovolcano stage were deposited over a timespan of 1.8 million years and cover an area roughly 20 kilometres (12 miles) long and 20 kilometres (12 miles) wide.[5][83]

Peralkalinity had remarkable effects on

liquidus temperatures of these flows were in excess of 1,200 degrees Celsius (2,190 degrees Fahrenheit) with viscosities as low as 100,000 poise. Glaciation and volcanism were contemporaneous during the bimodal stratovolcano stage as shown by the existence of volcano-glacial deposits in the volcanic edifice.[17]

Felsic dome-forming stage

A broad, low and gently sloping mountain cut by a U-shaped valley rising over a vegetated plain.
A U-shaped valley of Level Mountain with extensive elevated plateau in the foreground

By the

glacially eroded core of the bimodal stratovolcano.[17]

The felsic dome-forming stage extended over a timespan of two million years;[5] Meszah Peak, the highest point of both Level Mountain and the Level Mountain Range, formed at the end of this stage 2.5 million years ago.[2][3][5][86] Also emplaced at the end of this stage were comendite flows, ash flow tuffs and lava tubes.[86]

Quaternary stage

A fourth and final stage of volcanism began on the summit of Level Mountain in the last 2.5 million years, depositing lava in and adjacent to the Level Mountain Range. This lava is indirectly dated as

spatter cones, agglomerate and volcanic bombs,[s] as well as trachybasalt, mugearite and hawaiite lava flows. This activity was concentrated on and near Meszah Peak and on ridges 14 kilometres (8.7 miles) southeast and 10 kilometres (6.2 miles) south-southwest of Meszah.[50] Exposed on the south side of Level Mountain near Hatchau Lake is a rock outcrop consisting of boulders cemented together by calcareous sinter. This suggests an area of hot spring activity that may be related to volcanism at the mountain.[89]

Two tephra deposits, collectively known as the Finlay tephras, occur in organic-rich mud in the Dease Lake and Finlay River areas.[90] They both range in composition from phonolitic to trachytic and are 5 to 10 millimetres (0.20 to 0.39 inches) thick.[91] Radiocarbon dating of terrestrial plant macrofossils 2 to 2.5 centimetres (0.79 to 0.98 inches) above the youngest tephra deposit suggest an early Holocene age for this volcanic material.[92] Because Level Mountain has received little scientific study, it is a possible source for these tephra deposits along with Hoodoo Mountain, Heart Peaks and the Mount Edziza volcanic complex.[93]

Hazards and monitoring

Like other volcanic centres in the NCVP, Level Mountain is not monitored closely enough by the Geological Survey of Canada to ascertain its activity level. The Canadian National Seismograph Network has been established to monitor earthquakes throughout Canada, but it is too far away to provide an accurate indication of activity under the mountain. It may sense an increase in seismic activity if Level Mountain becomes highly restless, but this may only provide a warning for a large eruption; the system might detect activity only once the mountain has started erupting.[94] If Level Mountain were to erupt, mechanisms exist to orchestrate relief efforts. The Interagency Volcanic Event Notification Plan was created to outline the notification procedure of some of the main agencies that would respond to an erupting volcano in Canada, an eruption close to the Canada–United States border or any eruption that would affect Canada.[95]

The lava plateau margins of Level Mountain are vulnerable to landslides. This is particularly true around the steep south and west plateau boundaries where relatively clay-rich, incompetent layers of agglomerates and tuffs are present between more competent basaltic lava flows. Remnants of a 60,000-cubic-metre (2,100,000-cubic-foot) mudflow are present on the eastern slope of the Little Tahltan canyon. Similar older scars, including those in Beatty Creek, are visible around much of the lava plateau parameter.[28] Past eruptions of Level Mountain may have altered drainage patterns of local streams but their actual effects remain unknown.[96]

Human history

Occupation

A green-shaded relief map of a large, valley-cut, oval-shaped mountain with respective labels and elevations.
Topographic map of Level Mountain

In 1891–1892, the Hudson's Bay Company constructed a trail from the junction of the Sheslay and Hackett rivers to the southwestern slope of Level Mountain.[97] Here, the company had built a trading post by 1898 named Egnell after its operator Albert Egnell.[97][98] After spending one winter at the post, Egnell found that there was no trade to be done in the area and the post was subsequently abandoned. Egnell died on June 22, 1900, from an accidental gun shot to his leg by his son, McDonald, five days earlier and was buried at the Liard Post near the mouth of the Dease River.[99]

In the early 1900s, the Egnell Post served as a repair station for the 3,100-kilometre-long (1,900-mile) Yukon Telegraph Line, which extended from Ashcroft, British Columbia, to Dawson City, Yukon.[98][100] A small settlement consisting of a mission house and a number of other buildings had been established on the site by 1944. This settlement, named Sheslay, has since been abandoned.[98] There is no human population within 30 kilometres (19 miles) of Level Mountain but more than 630 people live within 100 kilometres (62 miles).[6]

Along the south side of Level Mountain are a number of other localities, including Hyland Ranch, Saloon, Salmon Creek Indian Reserve No. 3,

Tahltan Forks Indian Reserve No. 5. The northwestern side of Level Mountain is home to the Callison Ranch, which lies just east of Hatin Lake.[31] Southeast of Level Mountain is the Days Ranch near the junction of the Tahltan and Stikine rivers. It was established by Ira Day in or before 1929 as a stopping place on the road from Dease Lake to Telegraph Creek. Day operated the ranch until he died around 1960, after which it remained abandoned for a time.[101] In 2018, the Days Ranch was destroyed by a 30,000-hectare (74,000-acre) wildfire; more than 30 structures were burned.[102]

Geological studies

The large size and remote location of Level Mountain has limited geological studies at this volcanic complex.

granitic intrusives,[v] porphyries and greenstones. More definitive evidence as to their age was obtained by W. A. Johnston and F. A. Kerr of the Geological Survey of Canada who placed them in the Tertiary. Some of the most recent lava flows of the Stikine valley were assigned as probably belonging to the Pleistocene.[18]

3D depiction of a low, broad and rocky mountain rising over vegetated terrain dissected by valleys.
A 3D model of Level Mountain

Level Mountain was demonstrated in the 1920s as a possible source for the extensive lavas in the neighbouring

block faulting or by erosion of a formerly much more extensive surface underlain by horizontally bedded volcanic rocks.[107] The possibility of Level Mountain being a source for the Tuya field lavas would deteriorate in the 1940s when Canadian volcanologist Bill Mathews revealed that the flat-topped, steep-sided summits were not products of faulting or erosion but were rather individual volcanoes formed by eruptions of lava into lakes thawed through an ice sheet. Mathews coined the term "tuya" for these subglacial volcanoes after Tuya Butte which is located in the Tuya volcanic field. The recognition of Level Mountain as a long-lived zone of volcanism in contrast to the small Tuya field volcanoes has given it status as a separate volcanic centre.[108]

The mountain was identified by the mapping program of Operation Stikine in 1956.[109] This program, masterminded by Canadian volcanologist Jack Souther, was carried out over the Stikine River area using a Bell helicopter.[109][110] Reconnaissance mapping in 1962 by Jack Souther and Hu Gabrielse identified a sequence of lavas of late Tertiary to Quaternary age.[78] Level Mountain was then studied by T. S. Hamilton in the 1970s who produced a detailed map and the first petrochemical study of the lavas.[86] The andesites described in the 1920s were mapped as early Tertiary age, long before Level Mountain formed.[83] Hamilton recognized the four distinctive stratigraphic units of the lava plateau, as well as the overlying bimodal package of alkali basalt and peralkaline lavas and tuffs.[86]

In 1994, Carignnan et al. considered Level Mountain to be underlain by a

P-wave studies conducted in 1998 by Frederikson et al. did not detect any geophysical anomalies near the mountain to justify the existence of a mantle plume or hotspot.[112]

Naming

The name of the mountain is a reference to its plateau surface.

cartographers were uncertain as to what the name Level Mountain referred to. They cited H. S. Bostock's 1948 report Physiography of the Canadian Cordillera, With Special Reference to the Area North of the Fifty-Fifth Parallel in which Bostock stated that Level Mountain was a small prominent mountain range on the Nahlin Plateau.[113] Despite this misinterpretation, Level Mountain is still the local name for the entire volcanic edifice and the name Level Mountain Range for a group of steep peaks centered on the mountain's summit.[16][17] Although the mountain appears level when viewed from a distance, it attains the shape of a large triangle when examined from the top of some of the high hills west of the bend of the Tuya River.[44]

Accessibility

Vegetated terrain with a rocky, gently sloping mountain with large valleys carved into its slopes rising over the landscape.
Satellite image of Level Mountain showing its gently sloping surface

Level Mountain lies in a remote location with no established road access.[4] The closest route to this major volcanic complex is a graded road from Dease Lake to Telegraph Creek, which extends within 50 kilometres (31 miles) of the mountain.[4][114] From Telegraph Creek or Days Ranch the mountain may be reached by a 30-kilometre-long (19-mile) hike.[17] Several small low-lying lakes surrounding Level Mountain provide float plane access, including Ketchum Lake, Hatin Lake and Granite Lake.[4][17]

The Yukon Telegraph Trail, a historic pathway built in the 1890s, is still passable through Hatin Lake and provides an overland route to the shield volcano.[4] Alternatively, fixed-wing aircraft landings can be made on a runway at Sheslay. Charter helicopter service in the small community of Dease Lake provides direct access to the Level Mountain Range.[17] The alpine lava plateau of Level Mountain is easily travelled by horse or on foot during the snow-free period from June to September. Much of the area south of Level Mountain is impassable due to poorly-drained fens.[4]

See also

Notes

  1. ^ Nivation is erosion caused by freezing and thawing due to snow.[51]
  2. soil creep caused by waterlogged soil slowly moving downhill on top of an impermeable layer.[52]
  3. ^ Peralkaline rocks are magmatic rocks that have a higher ratio of sodium and potassium to aluminum.[54]
  4. ^ Mafic pertains to magmatic rocks that are relatively rich in iron and magnesium, relative to silicon.[56]
  5. aluminum, sodium and potassium.[56]
  6. ^ A dike is a sheet-shaped intrusion of magma into pre-existing rock.[61]
  7. ^ Welded tuff is a volcanic deposit composed of consolidated ash that has been hardened by hot gases, the action of heat and pressure from overlying material.[62]
  8. ^ Laccoliths are subterranean magmatic bodies that have uplifted overlying rocks while in a molten state.[63]
  9. ^ Agglomerate is a mass of angular volcanic fragments united by heat.[64]
  10. ^ Pumiceous pertains to the texture of pumice, which is characterized by several small cavities that give it a spongy, frothy appearance.[65]
  11. ^ Trachytic pertains to the texture of trachyte, which is characterized by crystals that show parallel alignment due to flow in the magma.[66]
  12. ^ Tuffaceous pertains to sediments which contain up to 50% tuff.[74]
  13. ^ Glacial erratics are glacially deposited rocks differing from the size and type of rock native to the area in which they rest.[75]
  14. ^ An outlier is an area of younger rock completely surrounded by older rocks.[76]
  15. ^ Siliceous sinter is a deposit of porous silica that forms around hot springs or geysers.[77]
  16. ^ Spheroidal weathering is a form of chemical weathering that results in the formation of concentric or spherical layers of decayed rock.[80]
  17. aluminum oxide lower than the combination of calcium oxide, sodium oxide and potassium oxide.[82]
  18. ^ Calc-alkaline pertains to magmatic rocks consisting of 55–61% silica.[84]
  19. ^ Volcanic bombs are rock fragments larger than 64 millimetres (2.5 inches) in diameter which form when a volcano ejects viscous fragments of lava during an eruption.[88]
  20. ^ Porphyritic pertains to the resemblance of porphyry which are magmatic rocks consisting of large crystals in a fine-grained matrix.[104]
  21. ^ The matrix is fine-grained background material in which large grains of a rock are embedded.[105]
  22. ^ Intrusives are rocks forced while in a molten state into cracks or layers of other rocks.[106]
  23. ^ Mantle plumes are large columns of hot rock rising through the mantle.[111]
  24. ^ Hotspots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle.[111]

References

  1. ^ a b c d "Level Mountain: Synonyms & Subfeatures". Global Volcanism Program. Smithsonian Institution. Archived from the original on 2021-06-04. Retrieved 2021-06-04.
  2. ^
    OCLC 601782234. Archived from the original
    (PDF) on 2018-11-14.
  3. ^ a b "Meszah Peak". BC Geographical Names. Retrieved 2017-01-15.
  4. ^ a b c d e f g h i j k Fenger et al. 1986, p. 2.
  5. ^ a b c d e f g h i j k l Wood & Kienle 1990, p. 121.
  6. ^ a b c d e f g "Level Mountain: General Information". Global Volcanism Program. Smithsonian Institution. Archived from the original on 2021-08-17. Retrieved 2024-01-30.
  7. ^ Fenger et al. 1986, p. 19.
  8. ^ a b c d e f g "Level Mountain Range". BC Geographical Names. Archived from the original on 2019-02-23. Retrieved 2024-01-30.
  9. ^ a b c d Wood & Kienle 1990, pp. 121, 123.
  10. ^ a b c Edwards & Russell 2000, p. 1283.
  11. ^ Hamilton & Scarfe 1977, pp. 429, 431, 432.
  12. ^ a b c d e Edwards & Russell 2000, p. 1284.
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Sources

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