HOME

TheInfoList



OR:

The Kitsu Plateau is a small intermontane plateau in
Cassiar Land District Cassiar Land District is a cadastral survey subdivision of the province of British Columbia, Canada, created with rest of those on Mainland British Columbia via the Lands Act of the Colony of British Columbia (1858–1866), Colony of British Columb ...
of northwestern
British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...
, Canada. It lies on the
Tahltan Highland The Tahltan Highland is an upland area of plateau and relatively lower mountain ranges in British Columbia, Canada, lying east of the Boundary Ranges and south of the Inklin River (the east fork of the Taku River). Its eastern boundary is formed ...
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 Mount Edziza Provincial Park is a provincial park in Cassiar Land District of northern British Columbia, Canada. It was established on 27 July 1972 to showcase the Mount Edziza volcanic complex and the surrounding Tahltan Highland. Geography The ...
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 Ejecta (; ) are particles ejected from an area. In volcanology, in particular, the term refers to particles including pyroclastic rock, pyroclastic materials (tephra) that came out of a explosive eruption, volcanic explosion and magma eruption v ...
. These lava flows and the associated ejecta originated from several volcanoes of the
Mount Edziza volcanic complex The Mount Edziza volcanic complex ( ; abbreviated MEVC) is a group of volcanoes and associated lava flows in northwestern British Columbia, Canada. Located on the Tahltan Highland, it is southeast of Telegraph Creek and southwest of Dease Lak ...
which has been the focus of volcanic activity over the last 7.5 million years. Alkali basalt,
hawaiite Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Ha ...
and
trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanite, aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrus ...
are among some of the
volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...
s comprising the Kitsu Plateau which is subdivided into five
geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...
s, each being the product of a distinct period of volcanic activity.
Volcanism Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...
on the plateau continued into the current
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
epoch and created the Mess Lake Lava Field which contains small
volcanic cone Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and s ...
s.


Geography and geomorphology


Location

The Kitsu Plateau is on the
Tahltan Highland The Tahltan Highland is an upland area of plateau and relatively lower mountain ranges in British Columbia, Canada, lying east of the Boundary Ranges and south of the Inklin River (the east fork of the Taku River). Its eastern boundary is formed ...
east of the
Boundary Ranges The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains. They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian pro ...
of the
Coast Mountains The Coast Mountains () are a major mountain range in the Pacific Coast Ranges of western North America, extending from southwestern Yukon through the Alaska Panhandle and virtually all of the British Columbia Coast, Coast of British Columbia sout ...
and west of the Skeena Mountains in
Cassiar Land District Cassiar Land District is a cadastral survey subdivision of the province of British Columbia, Canada, created with rest of those on Mainland British Columbia via the Lands Act of the Colony of British Columbia (1858–1866), Colony of British Columb ...
. Between the Boundary Ranges and the Kitsu Plateau is Mess Creek valley, which extends more than to the north where it separates the Zagoddetchino
massif A massif () is a principal mountain mass, such as a compact portion of a mountain range, containing one or more summits (e.g. France's Massif Central). In mountaineering literature, ''massif'' is frequently used to denote the main mass of an ...
from the
Big Raven Plateau 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 ...
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 whereas in the south the plateau is separated from Yagi Ridge by Nagha Creek valley. Roughly long and wide, the plateau lies at the southern end of the
Mount Edziza volcanic complex The Mount Edziza volcanic complex ( ; abbreviated MEVC) is a group of volcanoes and associated lava flows in northwestern British Columbia, Canada. Located on the Tahltan Highland, it is southeast of Telegraph Creek and southwest of Dease Lak ...
, which also includes the Big Raven Plateau to the north as well as the Spectrum Range and the Arctic Lake Plateau to the south. The volcanic complex consists of a group of overlapping
shield volcano A shield volcano is a type of volcano named for its low profile, resembling a shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more viscous lava ...
es,
stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...
es,
lava dome In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions ...
s and
cinder cone A cinder cone or scoria cone is a steep, volcanic cone, conical landform of loose pyroclastic rock, pyroclastic fragments, such as volcanic ash, clinkers, or scoria that has been built around a volcanic vent. The pyroclastic fragments are forme ...
s 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.


Drainage

As a part of the Mount Edziza volcanic complex, the Kitsu Plateau is drained entirely by streams within the Stikine River watershed. 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 A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...
of the Stikine River. 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 whereas Nagha Creek drains into Kitsu Creek just northeast of Mess Lake.


Structure

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. At the Mess Creek Escarpment, the Kitsu Plateau rises more than above Mess Lake in Mess Creek valley; Mess Lake has an elevation below whereas the Mess Creek Escarpment reaches an elevation of more than . The plateau surface is barren of vegetation, but at lower elevations the surrounding valleys contain
white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to: * '' Picea engelmannii'', native to the Rocky Mountains and Cascade Mountains of the United States and Canada * ''Picea glauca ''Picea glauca'', the whi ...
,
lodgepole pine ''Pinus contorta'', with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpin ...
and trembling aspen forests.


Landforms

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. It covers an area of around and contains three pyroclastic cones which were the sources of lava flows that travelled westward towards the Mess Creek Escarpment. The oldest cone, sometimes referred to by the
numeronym A numeronym is a word, usually an abbreviation, composed partially or wholly of numerals. The term can be used to describe several different number-based constructs, but it most commonly refers to a contraction in which all letters between the fir ...
ML-1, is at the northern end of the lava field, whereas the second oldest cone, ML-2, is at the southern end of the lava field. Both cones are covered by
tundra In physical geography, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...
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. 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.


Geology


Stratigraphy

The Kitsu Plateau is subdivided into at least five
geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...
s, each being the product of a distinct period of volcanic activity. 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 In geology, felsic is a grammatical modifier, modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted ...
magma. The two oldest geological formations comprising the Kitsu Plateau are the
Raspberry The raspberry is the edible fruit of several plant species in the genus ''Rubus'' of the Rosaceae, rose family, most of which are in the subgenus ''Rubus#Modern classification, Idaeobatus''. The name also applies to these plants themselves. Ras ...
and
Armadillo Armadillos () are New World placental mammals in the order (biology), order Cingulata. They form part of the superorder Xenarthra, along with the anteaters and sloths. 21 extant species of armadillo have been described, some of which are dis ...
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.


Raspberry Formation

The Raspberry Formation is exposed on the lower northern, western and southwestern sides of the Kitsu Plateau. It has an elevation of less than along the Mess Creek Escarpment and consists of flat-lying basaltic lava flows interbedded with
scoria Scoria or cinder is a pyroclastic, highly vesicular, dark-colored volcanic rock formed by ejection from a volcano as a molten blob and cooled in the air to form discrete grains called clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackso ...
. More than 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 The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...
erosion surface In geology and geomorphology, an erosion surface is a surface of rock (geology), rock or regolith that was formed by erosion and not by construction (e.g. lava flows, sediment deposition) nor fault (geology), fault displacement. Erosional surfaces ...
. 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 Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...
is 7.4–6.2 million years.


Armadillo Formation

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. Armadillo basalt flows are interbedded with air-fall
pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...
and
ash flow A pyroclastic flow (also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot volcanic gas, gas and volcanic matter (collectively known as tephra) that flows along the ground away from a volcano at average ...
s of trachytic and comenditic compositions. They were highly fluid and mobile at the time of their eruption as evidenced by their extreme persistence and relatively narrow thicknesses; individual basalt flows of this geological formation are less than thick. 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. In contrast, the interbedded air-fall pumice and ash flows probably originated from the more than in diameter Armadillo Peak
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
northeast of the Kitsu Plateau.


Nido Formation

Overlying the Armadillo Formation is the Kounugu Member, which is the only stratigraphic unit of the Nido Formation comprising the Kitsu Plateau. It consists of basaltic lava flows, flow
breccia Breccia ( , ; ) is a rock composed of large angular broken fragments of minerals or Rock (geology), rocks cementation (geology), cemented together by a fine-grained matrix (geology), matrix. The word has its origins in the Italian language ...
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. 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 A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...
swarms. Lava from the Swarm Peak eruptive centre is exposed along the Mess Creek Escarpment where it overlies
till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
and glacial-
fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...
gravel derived from the Armadillo Formation.


Spectrum Formation

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. This geological formation largely consists of comendite, pantellerite and pantelleritic trachyte; all three volcanic rocks comprise lava domes, lava flows and minor breccia and ash flow deposits. Spectrum trachyte flows on the Kitsu Plateau are the most distal remnants of the main Spectrum Dome and are relatively thin compared to those forming the adjacent Spectrum Range. 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. 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.


Big Raven Formation

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 Tephra is fragmental material produced by a Volcano, volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, ...
. These
volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...
s were deposited by eruptions during the
Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
and mainly comprise the Mess Lake Lava Field, one of the three Big Raven lava fields of the Mount Edziza volcanic complex. 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. The Ash Pit, which may be the youngest eruptive centre of the entire Mount Edziza volcanic complex, was the source of a long and wide hawaiitic air-fall tephra deposit that extends to the north-northeast on the Kitsu Plateau. It was also the source of a hawaiitic lava flow that travelled to the northwest through Nagha Creek valley towards Mess Lake. Residual heat from The Ash Pit eruption may have resulted in the formation of the Mess Lake Hot Springs to the west in Mess Creek valley.


Basement

As a part of the Mount Edziza volcanic complex, the Kitsu Plateau is underlain by the Stikinia
terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its d ...
. This is a
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
and
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
suite of volcanic,
sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...
and
metamorphic Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...
rocks that accreted to the
continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental marg ...
of North America during the Jurassic. 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 conglomerate (geology), conglomerates, sandstones, arkoses, siltstones, shales or minor coal.


Name and etymology

The name of the plateau became official on January 2, 1980, and was adopted on the National Topographic System map 104G/10 after being submitted to the BC Geographical Names office by the Geological Survey of Canada. It means 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 on January 2, 1980, on the National Topographic System maps 104G/10 and 104G/7, respectively.


Provincial park

The Kitsu Plateau lies at the southern end of
Mount Edziza Provincial Park Mount Edziza Provincial Park is a provincial park in Cassiar Land District of northern British Columbia, Canada. It was established on 27 July 1972 to showcase the Mount Edziza volcanic complex and the surrounding Tahltan Highland. Geography The ...
, a protected area founded in 1972 to showcase the volcanic landscape. 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. Mount Edziza Provincial Park covers , making it one of the largest provincial parks in British Columbia. Hunting, camping, fishing, hiking, wildlife viewing and nature studying are some of the activities available in Mount Edziza Provincial Park. 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 range. However, temperatures can drop below freezing during summer nights, making snow or freezing rain a possibility at any time of the year.


Accessibility

From near the Eastman Creek Rest Area south of Kinaskan Lake on the Stewart–Cassiar Highway, the historic Yukon Telegraph Trail extends about west to the Little Iskut River. From there, it enters Mount Edziza Provincial Park and continues another west along Bourgeaux Creek through Raspberry Pass. The telegraph trail then continues to the northwest through Raspberry Creek valley along the northern edge of the Kitsu Plateau for about to Mess Creek valley. Only short segments of the Yukon Telegraph Trail are still passable, having been mostly overgrown since maintenance of the trail ended in 1936. 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. Private aircraft are prohibited from landing on the Kitsu Plateau lava flows, but Mess Lake is large enough to be used by float-equipped aircraft. Landing on the lake with a private aircraft requires a letter of authorization from the BC Parks Stikine Senior Park Ranger.


See also

*List of plateaus in British Columbia


References


Sources

* {{Plateaus and highlands of British Columbia Plateaus of the Mount Edziza volcanic complex Miocene volcanism Pliocene volcanism Holocene volcanism Tahltan place names