Kitsu Plateau | |
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Coordinates: 57°27′59″N130°45′06″W / 57.46639°N 130.75167°W [1] | |
Location | Cassiar Land District, British Columbia, Canada [2] |
Range | Tahltan Highland [2] |
Part of | Mount Edziza complex [3] |
Age | 7.4 Ma to less than 20 ka [4] [5] |
Formed by | Volcanic activity [6] |
Geology | Comendite, trachyte, hawaiite, alkali basalt [5] |
Etymology | Northern lights (Tahltan) [1] |
Dimensions | |
• Length | Approximately 10 km (6.2 mi) [2] |
• Width | Approximately 6 km (3.7 mi) [2] |
Elevation | Above 1,700 m (5,500 ft) [2] |
Last eruption | Holocene age [7] [8] |
Topo map | NTS 104G10 Mount Edziza [1] NTS 104G7 Mess Lake [1] |
Designation | Mount Edziza Provincial Park [2] |
Borders on | Spectrum Range (southeast) [2] Nagha Creek valley (south) [2] Mess Creek valley (west) [2] Raspberry Pass (north) [2] Artifact Ridge (east) [2] |
Location in Mount Edziza Provincial Park |
The Kitsu Plateau is a small intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Nagha Creek and Raspberry Creek. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the valleys, it is relatively barren of vegetation. Surrounding the Kitsu Plateau is Mount Edziza Provincial Park which is one of the largest provincial parks in British Columbia. Access to this remote plateau is mainly by aircraft since motorized vehicles are prohibited from entering Mount Edziza Provincial Park.
The Kitsu Plateau is volcanic in origin, consisting of lava flows that are interbedded with volcanic ejecta. These lava flows and the associated ejecta originated from several volcanoes of the Mount Edziza volcanic complex which has been the focus of volcanic activity over the last 7.5 million years. Alkali basalt, hawaiite and trachyte are among some of the volcanic rocks comprising the Kitsu Plateau which is subdivided into five geological formations, each being the product of a distinct period of volcanic activity. Volcanism on the plateau continued into the current Holocene epoch and created the Mess Lake Lava Field which contains small volcanic cones.
The Kitsu Plateau is on the Tahltan Highland east of the Boundary Ranges of the Coast Mountains and west of the Skeena Mountains in Cassiar Land District. Between the Boundary Ranges and the Kitsu Plateau is Mess Creek valley which extends more than 30 kilometres (19 miles) to the north where it separates the Zagoddetchino massif from the Big Raven Plateau in the east. The northern end of the plateau is bounded by Raspberry Pass which contains the east-flowing Bourgeaux Creek in the east and the northwest-flowing Raspberry Creek in the west. Between the Kitsu Plateau and the Skeena Mountains is Artifact Ridge and the Little Iskut River, the latter of which flows north in a north–south trending valley and then flows southeast towards the Skeena Mountains into the Iskut River. In the southeast, the Kitsu Plateau is surrounded by the Spectrum Range while in the south the plateau is separated from Yagi Ridge by Nagha Creek valley. [2]
This roughly 10-kilometre-long (6.2-mile) and 6-kilometre-wide (3.7-mile) plateau lies at the southern end of the Mount Edziza volcanic complex which also includes the Big Raven Plateau to the north, as well as the Spectrum Range and the Arctic Lake Plateau to the south. [2] [3] This volcanic complex consists of a group of overlapping shield volcanoes, stratovolcanoes, lava domes and cinder cones that have formed over the last 7.5 million years. It contains four central volcanoes along its north–south trending axis; from north to south they are Mount Edziza, Ice Peak, Armadillo Peak and the Spectrum Range. [6]
As a part of the Mount Edziza volcanic complex, the Kitsu Plateau is drained entirely by streams within the Stikine River watershed. [2] [9] The only named stream on the plateau is Kitsu Creek which originates on the northern flank of Kitsu Peak in the Spectrum Range and flows northwest then north into Mess Creek, a tributary of the Stikine River. [5] [10] [11] Several small unnamed streams flow into Kitsu Creek and the neighbouring valleys of Mess Creek, Raspberry Creek and Nagha Creek; Raspberry Creek drains into Mess Creek while Nagha Creek drains into Kitsu Creek just northeast of Mess Lake. [11] [12] [13]
The western, northern and southern edges of the Kitsu Plateau are marked by steep cliffs forming the Mess Creek Escarpment, the southern side of Raspberry Creek valley and the northern side of Nagha Creek valley, respectively. [2] [5] At the Mess Creek Escarpment, the Kitsu Plateau rises more than 910 metres (3,000 feet) above Mess Lake in Mess Creek valley; Mess Lake has an elevation below 760 metres (2,500 feet) while the Mess Creek Escarpment reaches an elevation of more than 1,700 metres (5,500 feet). [2] The plateau surface is barren of vegetation, but at lower elevations the surrounding valleys contain white spruce, lodgepole pine and trembling aspen forests. [2] [14]
The Kitsu Plateau is dominated by the Mess Lake Lava Field which extends from Raspberry Creek in the north to Nagha Creek in the south. [2] [15] It covers an area of around 18 square kilometres (6.9 square miles) and contains three pyroclastic cones which were the source of lava flows that travelled westward towards the Mess Creek Escarpment. [15] The oldest cone, sometimes referred to by the numeronym ML-1, is at the northern end of the lava field while the second oldest cone, ML-2, is at the southern end of the lava field. [16] Both cones are covered by tundra vegetation and have been slightly rounded by erosion, although their craters are still recognizable. The Ash Pit, sometimes referred to by the numeronym ML-3, is the youngest and southernmost eruptive centre of the Mess Lake Lava Field. [16] It lies on the steep southern slope of the Kitsu Plateau inside Nagha Creek valley and has been described as a pyroclastic cone or a conical explosion crater. [5] [17]
The Kitsu Plateau is subdivided into at least five geological formations, each being the product of a distinct period of volcanic activity. [5] [4] These periods of volcanic activity occurred during three magmatic cycles of the Mount Edziza volcanic complex; each cycle began with the effusion of alkali basalt and culminated with the eruption of lesser volumes of felsic magma. [18] The two oldest geological formations comprising the Kitsu Plateau are the Raspberry and Armadillo formations which were deposited by volcanic eruptions during the first magmatic cycle between 7.5 and 6 million years ago. Overlying these two geological formations are the Nido and Spectrum formations which were deposited between 6 and 3 million years ago during the second magmatic cycle. The fifth oldest geological formation comprising the Kitsu Plateau is the Big Raven Formation which was deposited during the fifth magmatic cycle in the last 20,000 years. [5] [4]
The Raspberry Formation is exposed on the lower northern, western and southwestern sides of the Kitsu Plateau. [5] It has an elevation of less than 1,310 metres (4,300 feet) along the Mess Creek Escarpment and consists of flat-lying basaltic lava flows interbedded with scoria. [19] More than 180 metres (590 feet) of Raspberry lava flows are exposed in the Mess Creek Escarpment, most of which were erupted from a shield volcano that formed on a Late Miocene erosion surface. [20] [21] These lava flows travelled westward into the ancestral valley of Mess Creek and originated from vents north of Raspberry Pass which were subsequently buried under younger volcanic deposits. A minimum age for the timing of Raspberry volcanism is 7.4–6.2 million years. [21]
Basaltic lava flows of the 6.3-million-year-old Armadillo Formation are exposed on the northern side of the plateau and along the Mess Creek Escarpment on the western side of the plateau where they overlie basaltic lava flows of the Raspberry Formation. [5] [4] Armadillo basalt flows are interbedded with air-fall pumice and ash flows of trachytic and comenditic compositions and were highly fluid and mobile at the time of their eruption as evidenced by their extreme persistence and relatively narrow thicknesses; individual basalt flows are normally less than 3 metres (9.8 feet) thick. [21] [22] The source of these flows was probably a cluster of vents further to the north called Sezill Volcano which may have been active prior to the onset of Armadillo volcanism. [22] In contrast, the air-fall pumice and ash flows probably originated from the more than 4-kilometre-in diameter (2.5-mile) Armadillo Peak caldera northeast of the Kitsu Plateau. [21] [6]
Overlying the Armadillo Formation is the Kounugu Member which is the only stratigraphic unit of the Nido Formation comprising the Kitsu Plateau. [5] It consists of basaltic lava flows, flow breccia and agglutinate which were erupted 4.4 million years ago from at least four eruptive centres; these eruptive centres have since been deeply eroded and buried under younger volcanic deposits. [5] [23] At least some of the Kounugu lava flows comprising the Kitsu Plateau may have originated from Swarm Peak further to the east which issued lava that travelled westward; remains of the Swarm Peak eruptive centre are in the form of north-trending fissure swarms. [24] Lava from the Swarm Peak eruptive centre is exposed along the Mess Creek Escarpment where it overlies till and glacial-fluvial gravel derived from the Armadillo Formation. [25]
The Kounugu Member is overlain by the 3.1-million-year-old Spectrum Formation which is exposed along the Mess Creek Escarpment on the western side of the plateau and at the southern and eastern ends of the plateau. [5] [4] This geological formation largely consists of comendite, pantellerite and pantelleritic trachyte which are in the form of lava domes and lava flows, as well as minor breccia and ash flow deposits. [5] Spectrum trachyte flows on the Kitsu Plateau are relatively thin compared to those forming the adjacent Spectrum Range, but they are the most distal remnants of the main Spectrum Dome. [10] These trachyte flows are overlain by alkali basalt of the Kitsu Member which is mainly exposed at the southern end of the Kitsu Plateau and along the western edge of the plateau. [5] This alkali basalt is in the form of lava flows and likely originated from vents of the Spectrum Dome which have since been destroyed by erosion. [26]
The Big Raven Formation is the youngest and uppermost geological formation comprising the Kitsu Plateau, consisting of hawaiite and alkali basalt in the form of lava flows, lava bombs, agglutinate and air-fall tephra. [5] These volcanic rocks were deposited by eruptions during the Holocene and mainly comprise the Mess Lake Lava Field, one of the three Big Raven lava fields of the Mount Edziza volcanic complex. [5] [4] [27] Alkali basalt flows from the two oldest pyroclastic cones in the Mess Lake Lava Field, ML-1 and ML-2, most likely cascaded over the Mess Creek Escarpment into Mess Creek valley, but no evidence of this phenomenon has been found on or below the escarpment. [15] The Ash Pit, which may be the youngest eruptive centre of the entire Mount Edziza volcanic complex, was the source of a 6.5-kilometre-long (4.0-mile) and 2.5-kilometre-wide (1.6-mile) hawaiitic air-fall tephra deposit that extends to the north-northeast on the Kitsu Plateau. [5] [28] The Ash Pit was also the source of a hawaiitic lava flow that travelled 3.5 kilometres (2.2 miles) to the northwest through Nagha Creek valley towards Mess Lake. [5] Residual heat from The Ash Pit eruption may have resulted in the formation of the Mess Lake Hot Springs 2.5 kilometres (1.6 miles) to the west in Mess Creek valley. [2] [29]
As a part of the Mount Edziza volcanic complex, the Kitsu Plateau is underlain by the Stikinia terrane. [3] [30] This is a Paleozoic and Mesozoic suite of volcanic, sedimentary and metamorphic rocks that accreted to the continental margin of North America during the Jurassic. [5] [30] [31] The rocks of this terrane are exposed to the south and southwest where they are largely buried under landslide and colluvium deposits, as well as stream gravel, outwash and braided channel deposits. Minor exposures of Cretaceous–Paleocene sedimentary rocks assigned to the Sustut Group are present in the mouth of Nagha Creek valley at the southwestern end of the Kitsu Plateau and are in the form of conglomerates, sandstones, arkoses, siltstones, shales or minor coal. [5]
The name of the plateau was adopted 2 January 1980 on the National Topographic System map 104G/10 after being submitted to the BC Geographical Names office by the Geological Survey of Canada. [1] It means northern lights in the Tahltan language and was likely chosen due to the plateau's association with Kitsu Creek and Kitsu Peak whose names were also adopted 2 January 1980 on the National Topographic System maps 104G/10 and 104G/7, respectively. [1] [32] [33]
The Kitsu Plateau lies at the southern end of Mount Edziza Provincial Park, a protected area founded in 1972 to showcase the volcanic landscape. [2] [14] This remote wilderness area of northwestern British Columbia is not accessible by motorized vehicles to help protect the very sensitive environment. Instead, access is mainly via aircraft or unmaintained hiking trails that cross creeks. [14] Mount Edziza Provincial Park covers 266,180 hectares (657,700 acres), making it one of the largest provincial parks in British Columbia. [14] [34] Hunting, camping, fishing, hiking, wildlife viewing and nature studying are some of the activities available in Mount Edziza Provincial Park. [14]
Wildlife in the area includes moose, caribou, mountain goats, stone sheep, wolves, bears, squirrels, owls, ptarmigans, ravens, gyrfalcons, grouse and migratory songbirds. The climate is characterized by warm summers and cold, snowy winters; temperatures are warmest in mid-summer during the day when they may hit the 30 degrees Celsius (86 degrees Fahrenheit) range. However, temperatures can drop below freezing during summer nights, making snow or freezing rain a possibility at any time of the year. [14]
From near the Eastman Creek Rest Area south of Kinaskan Lake on the Stewart–Cassiar Highway, the historic Yukon Telegraph Trail extends about 15 kilometres (9.3 miles) west to the Little Iskut River. From there, it enters Mount Edziza Provincial Park and continues another 15 kilometres (9.3 miles) west along Bourgeaux Creek through Raspberry Pass. [35] The telegraph trail then continues to the northwest through Raspberry Creek valley along the northern edge of the Kitsu Plateau for about 15 kilometres (9.3 miles) to Mess Creek valley. [2] [35] Only short segments of the Yukon Telegraph Trail are still passible, having been mostly overgrown since maintenance of the trail ended in 1936. [36]
The Kitsu Plateau can be accessed by float plane or helicopter, both of which are available for charter at the communities of Iskut and Dease Lake. [36] Private aircraft are prohibited from landing on the Kitsu Plateau lava flows. Mess Lake is large enough to be used by float-equipped aircraft, but landing on it with a private aircraft requires a letter of authorization from the BC Parks Stikine Senior Park Ranger. [14]
Mount Edziza, known to the local Tahltan people as Tenh Dẕetle, is a volcanic mountain in Cassiar Land District of northwestern British Columbia, Canada. It is located on the Big Raven Plateau of the Tahltan Highland which extends along the western side of the Stikine Plateau. Mount Edziza has an elevation of 2,786 metres, making it the highest point of the Mount Edziza volcanic complex. However, it had an elevation of at least 3,396 metres before its formerly cone-shaped summit was likely destroyed by a violent eruption in the geologic past; its current flat summit contains an ice-filled, 2-kilometre-in diameter (1.2-mile) crater. The mountain contains several lava domes, cinder cones and lava fields on its flanks, as well as an ice cap containing several outlet glaciers which stretch out to lower altitudes. All sides of Mount Edziza are drained by tributaries of Mess Creek and Kakiddi Creek which are situated within the Stikine River watershed.
The Spectrum Range, formerly gazetted as the Spectrum Mountains and the Rainbow Mountains, is a small mountain range in Cassiar Land District of northwestern British Columbia, Canada. Located at the southern end of the Tahltan Highland, it borders the Skeena Mountains in the east and the Boundary Ranges of the Coast Mountains in the west. The Spectrum Range is surrounded by the Arctic Lake Plateau in the southwest and the Kitsu Plateau in the northwest, both of which contain volcanic features such as cinder cones. It lies at the southern end of the Mount Edziza volcanic complex which includes the two neighbouring plateaus as well as Mount Edziza and the Big Raven Plateau to the north. The mountain range is drained on all sides by streams within the Stikine River watershed and, unlike Mount Edziza to the north, contains relatively small separate glaciers. Mount Edziza Provincial Park is the main protected area surrounding the Spectrum Range.
Nahta Cone is a small cinder cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 1,670 metres and lies near the northern edge of the Arctic Lake Plateau, a glacially scored plateau of the Tahltan Highland which in turn extends along the western side of the Stikine Plateau. The cone is about 70 kilometres south-southeast of the community of Telegraph Creek and lies in the southwestern corner of Mount Edziza Provincial Park, one of the largest provincial parks in British Columbia.
The Big Raven Plateau is an intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Kakiddi Creek, Chakima Creek, Walkout Creek and the Klastline River. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the valleys, it is relatively barren of vegetation. Stream erosion has resulted in the creation of canyons with intervening ridges on the eastern and western sides of the plateau, resulting in the creation of rugged terrain. The plateau is in Mount Edziza Provincial Park which is one of the largest provincial parks in British Columbia. Access to the Big Raven Plateau is mainly by aircraft or by a network of footpaths from surrounding roads.
Tennena Cone, alternatively Icebridge Cone, is a small volcanic cone in Cassiar Land District of northwestern British Columbia, Canada. It has an elevation of 2,390 metres and lies on the western flank of Ice Peak, the prominent south peak of Mount Edziza. The cone is almost completely surrounded by glacial ice of Mount Edziza's ice cap which covers an area of around 70 square kilometres. Tennena Cone is 200 metres high, 1,200 metres long and up to 600 metres wide, its symmetrical structure resembling a black pyramid. The cone and the surrounding area are in Mount Edziza Provincial Park which also includes the Spectrum Range to the south.
The Mount Edziza volcanic complex is a group of volcanoes and associated lava flows in northwestern British Columbia, Canada. Located on the Tahltan Highland, it is 40 kilometres southeast of Telegraph Creek and 85 kilometres southwest of Dease Lake. The complex encompasses a broad, steep-sided lava plateau that extends over 1,000 square kilometres. Its highest summit is 2,786 metres in elevation, making the MEVC the highest of four large complexes in an extensive north–south trending volcanic region. It is obscured by an ice cap characterized by several outlet glaciers that stretch out to lower altitudes.
Cartoona Ridge is a mountain ridge extending east from the eastern side of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Shaman Creek valley, on the south by Chakima Creek valley, on the east by Kakiddi Creek valley and on the west by the Big Raven Plateau. Its highest point and only named peak is Cartoona Peak at the westernmost end of the ridge with an elevation of 2,300 metres. Carttona Ridge is one of three ridges east of the Big Raven Plateau named by Canadian volcanologist Jack Souther, the other two being Idiji Ridge and Sorcery Ridge to the north.
The Little Iskut Formation is a stratigraphic unit of Miocene age in northwestern British Columbia, Canada.
The Mess Creek Escarpment is a long, discontinuous cliff along Mess Creek in Cassiar Land District of northwestern British Columbia, Canada. It forms the east-central side of Mess Creek valley and consists of two segments separated about 5 kilometres by Walkout Creek valley. The northern segment extends about 8 kilometres southeast along the southwestern side of the Big Raven Plateau while the southern segment extends generally south along the northwestern, western and southwestern edges of the Kitsu Plateau for about 10 kilometres. With an elevation of more than 1,700 metres, the Mess Creek Escarpment rises more than 910 metres above the floor of Mess Creek valley. The escarpment lies within the boundaries of Mount Edziza Provincial Park.
The volcanic history of the Northern Cordilleran Volcanic Province presents a record of volcanic activity in northwestern British Columbia, central Yukon and the U.S. state of easternmost Alaska. The volcanic activity lies in the northern part of the Western Cordillera of the Pacific Northwest region of North America. Extensional cracking of the North American Plate in this part of North America has existed for millions of years. Continuation of this continental rifting has fed scores of volcanoes throughout the Northern Cordilleran Volcanic Province over at least the past 20 million years and occasionally continued into geologically recent times.
Mess Creek, formerly known as Mestua, is a tributary of the Stikine River in northwestern British Columbia, Canada. It flows north and northwest for about 110 km (68 mi), through a lake and a gorge to join the Stikine River, which in turn flows southwest across the Canada–United States border into Alaska where it empties into various straits of the Inside Passage. The northern half of Mess Creek forms a western boundary of Mount Edziza Provincial Park which lies within the traditional territory of the Tahltan people.
The Big Raven Formation is a stratigraphic unit of Quaternary age in northwestern British Columbia, Canada. It is the youngest and least voluminous geological formation of the Mount Edziza volcanic complex (MEVC); it overlies at least six older formations of this volcanic complex. The main volcanic rocks of the Big Raven Formation are alkali basalts and hawaiites, although a small volume of trachyte comprises the Sheep Track Member. These rocks were deposited by volcanic eruptions in the last 20,000 years during the latest magmatic cycle of the MEVC. Alkali basalt and hawaiite are in the form of lava flows and small volcanic cones while trachyte of the Sheep Track Member is mainly in the form of volcanic ejecta which covers an area of about 40 square kilometres.
The Klastline Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada.
Kitsu Creek is a tributary of Mess Creek and part of the Stikine River watershed in northwest part of the province of British Columbia, Canada. It flows generally northwest and north for roughly 22.5 km (14.0 mi) to join Mess Creek, a tributary of the Stikine River.
Nagha Creek is a tributary of Kitsu Creek and part of the Stikine River watershed in northwest part of the province of British Columbia, Canada. It flows generally northwest and north for roughly 15 km (9.3 mi) to join Kitsu Creek, a tributary of Mess Creek, which in turn is a tributary of the Stikine River.
The Mount Edziza volcanic complex (MEVC) in British Columbia, Canada, has a history of volcanism that spans more than 7 million years. It has taken place during five cycles of magmatic activity, each producing less volcanic material than the previous one. Volcanism during these cycles has created several types of volcanoes, including cinder cones, stratovolcanoes, subglacial volcanoes, shield volcanoes and lava domes. The roughly 1,000-square-kilometre (400-square-mile) volcanic plateau forming the base of the MEVC originated from the successive eruptions of highly mobile lava flows. Volcanic rocks such as basalt, trachybasalt, benmoreite, tristanite, mugearite, trachyte and rhyolite were deposited by multiple eruptions of the MEVC; the latter six rock types are products of varying degrees of magmatic differentiation in underground magma reservoirs. At least 10 distinct flows of obsidian were produced by volcanism of the MEVC, some of which were exploited by indigenous peoples in prehistoric times to make tools and weaponry. Renewed volcanism could produce explosive eruptions and block local streams with lava flows.
The Edziza Formation is a stratigraphic unit of Pleistocene age in northwestern British Columbia, Canada. First described in 1984, the Edziza Formation was mapped as one of several geological formations of the Mount Edziza volcanic complex. It overlies at least four other geological formations of this volcanic complex that differ in age and composition. The main volcanic rock comprising the Edziza Formation is trachyte which was deposited by volcanic eruptions at the end of the third magmatic cycle of the Mount Edziza volcanic complex 0.9 million years ago.
Artifact Ridge is a mountain ridge extending southeast from the eastern side of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Bourgeaux Creek valley, on the south by Artifact Creek valley, on the east by the Little Iskut River valley and on the west by the Kitsu Plateau. The ridge is at the southeastern end of Mount Edziza Provincial Park and gets its name from the knapping of obsidian tools and points by early Tahltan hunters. Destell Pass cuts north–south through the westernmost end of Artifact Ridge.
Yagi Ridge is a mountain ridge extending northwest from the middle of the Spectrum Range at the southern end of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the north by Nagha Glacier and Nagha Creek valley, on the south by Yeda Creek on the Arctic Lake Plateau and on the west by Mess Creek valley. Yagi Ridge reaches an elevation of 2,243 metres at the head of Nagha Glacier where its eastern end adjoins to the Spectrum Range just northwest of Yeda Peak.
Kitsu Peak is the highest summit of the Spectrum Range at the southern end of the Mount Edziza volcanic complex in northwestern British Columbia, Canada. It is bounded on the west by Nagha Creek valley, on the northwest by the Kitsu Plateau, on the northeast by Obsidian Ridge, on the east by Stewbomb Creek valley and on the southwest by Nagha Glacier and Yagi Ridge. It has an elevation of 2,430 metres and lies at the northern end of the Spectrum Range.