Maitland Volcano
Encyclopedia
Maitland Volcano was a Pliocene
age shield volcano
in the western Cassiar Mountains
of northwestern British Columbia
, Canada
. In the course of one million years, Maitland Volcano was formed on a mature, eroded Tertiary
surface by rift
ing of the North America
n continent as thin alkali olivine
basalt
and hawaiite
lava flows covered the surrounding area. In the four million years since the volcano was active, erosion has been extensive, exposing a cluster of 14 steep-sided volcanic plug
s and scattered, cliff-bounded basalt lava flows that were originally part of the >900 km2 shield volcano. All volcanic plugs are about 30 m (98 ft) wide and are the only known vents for the basaltic and hawaiite lavas. The cliff-bounded basalt lavas cover the higher mountain
s of the Cassiar Mountains and individual lavas covering the mountains are up to 230 m (755 ft) thick and contain from 1 m (3 ft) to 20 m (66 ft) lava flows of columnar basalt separated by beds of scoria
ceous flow-topped breccia and tephra
. Intervening valleys, deeply incised into the underlying Jurassic
shale
and sandstone
, are as much as 600 m (1,969 ft) below the base of the former Maitland shield volcano. These volcanics form part of the rift-related Northern Cordilleran Volcanic Province
.
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
age shield volcano
Shield volcano
A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...
in the western Cassiar Mountains
Cassiar Mountains
The Cassiar Mountains are the most northerly group of the Northern Interior Mountains in the Canadian province of British Columbia and the Yukon Territory. They lie north and west of the Omineca Mountains, west of the northernmost Rockies and the Rocky Mountain Trench, north of the Hazelton...
of northwestern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. In the course of one million years, Maitland Volcano was formed on a mature, eroded Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
surface by rift
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
ing of the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n continent as thin alkali olivine
Olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
and hawaiite
Hawaiite
Hawaiite is an olivine basalt with intermediate composition between alkali olivine and mugearite. It was first described at the island of Hawaii. In gemology, hawaiite is a colloquial term for Hawaii-originated peridot,which is gem-quality olivine mineral....
lava flows covered the surrounding area. In the four million years since the volcano was active, erosion has been extensive, exposing a cluster of 14 steep-sided volcanic plug
Volcanic plug
A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when magma hardens within a vent on an active volcano. When forming, a plug can cause an extreme build-up of pressure if volatile-charged magma is trapped beneath it, and this can sometimes lead to an...
s and scattered, cliff-bounded basalt lava flows that were originally part of the >900 km2 shield volcano. All volcanic plugs are about 30 m (98 ft) wide and are the only known vents for the basaltic and hawaiite lavas. The cliff-bounded basalt lavas cover the higher mountain
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
s of the Cassiar Mountains and individual lavas covering the mountains are up to 230 m (755 ft) thick and contain from 1 m (3 ft) to 20 m (66 ft) lava flows of columnar basalt separated by beds of scoria
Scoria
Scoria is a volcanic rock containing many holes or vesicles. It is most generally dark in color , and basaltic or andesitic in composition. Scoria is relatively low in mass as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity...
ceous flow-topped breccia and tephra
Tephra
200px|thumb|right|Tephra horizons in south-central [[Iceland]]. The thick and light coloured layer at center of the photo is [[rhyolitic]] tephra from [[Hekla]]....
. Intervening valleys, deeply incised into the underlying Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
and sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, are as much as 600 m (1,969 ft) below the base of the former Maitland shield volcano. These volcanics form part of the rift-related Northern Cordilleran Volcanic Province
Northern Cordilleran volcanic province
The Northern Cordilleran Volcanic Province , formerly known as the Stikine Volcanic Belt, is a geologic province defined by the occurrence of Miocene to Holocene volcanoes in the Pacific Northwest of North America...
.
See also
- List of volcanoes in Canada
- List of Northern Cordilleran volcanoes
- Volcanism of Canada
- Volcanism of Western CanadaVolcanism of Western CanadaVolcanism of Western Canada produces lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds.-Volcanic belts:*Anahim...