The Tseax Cone ( ), also called the Tseax River Cone or the Aiyansh Volcano, is a young and active

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

and adjacent lava flows associated with the

Nass Ranges The Nass Ranges are a mountain range north of the Skeena River, west of Hazelton, and northeast of Terrace, British Columbia, Canada. It is associated with the Hazelton Mountains, which in turn form part of the Interior Mountains.Northern Cordilleran Volcanic Province The Northern Cordilleran Volcanic Province (NCVP), 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. This belt of volcanoes ex ...

. It is located east of Crater Creek at outlet of Melita Lake, southeast of Gitlakdamix and north of

Terrace, British Columbia Terrace is a city located near the Skeena River in British Columbia, Canada. The community is the regional retail and service hub for the northwestern portion of British Columbia. With a current population of over 12,000 within municipal boundarie ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. The volcano is in a valley above and east of the

Tseax River The Ksi Sii Aks (formerly Tseax River) is a tributary of the Nass River in northwestern British Columbia, Canada. It is most notable as the namesake of Tseax Cone, a volcano within its basin that was responsible for an eruption in the 17th century ...

, about south of the river's junction with the larger

Nass River The Nass River is a river in northern British Columbia, Canada. It flows from the Coast Mountains southwest to Nass Bay, a sidewater of Portland Inlet, which connects to the North Pacific Ocean via the Dixon Entrance. Nass Bay joins Portland In ...

. The Tseax Cone is one of the most accessible volcanic centres in British Columbia.

Geology

Northern Cordilleran Volcanic Province map

The Tseax Cone is in the southern part of the

Northern Cordilleran Volcanic Province The Northern Cordilleran Volcanic Province (NCVP), 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. This belt of volcanoes ex ...

and is therefore part of the

Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring o ...

. It has been the site of some of the youngest volcanic eruptions in Canada. It has been active at least twice in the past few hundred years and other remnants of lava flows exist in the area. It is in diameter at its base and rests on the remnants of an earlier and somewhat larger, dissected, diameter cone. The volcano is made of

volcanic bomb A volcanic bomb or lava bomb is a mass of partially molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption. Because volcanic bombs cool after they l ...

s and

cinder Cinder is an alternate term for scoria. Cinder or Cinders may also refer to: In computing *Cinder (programming library), a C++ programming library for visualization *Cinder, OpenStack's block storage component * Cyber Insider Threat, CINDER, a ...

s with a crater at its summit where a churning

lava lake Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (someti ...

poured and overflowed its rim during the 18th century.Nisga'a Memorial Lava Beds Provincial Park
Retrieved on 2008-02-13 Volcanism at the Tseax Cone is caused by the

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ing of the Earth's crust where two parts of the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

are breaking apart. The rifting is the result of the

Pacific Plate The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...

sliding northward along the

transform Transform may refer to: Arts and entertainment * Transform (scratch), a type of scratch used by turntablists * ''Transform'' (Alva Noto album), 2001 * ''Transform'' (Howard Jones album) or the title song, 2019 * ''Transform'' (Powerman 5000 album ...

Queen Charlotte Fault The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Ch ...

, on its way to the

Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulakh ...

. The

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

emitted in eruptions at the Tseax Cone is fluid. Its lavas are made of

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

, a common grey to black or dark brown

extrusive Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. In contras ...

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic r ...

low in

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

content (the lava is

mafic A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include ...

) that is usually fine-grained due to rapid cooling of lava on the Earth's surface.

Pāhoehoe Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

is found at the volcano, which has a smooth, billowy, undulating, or ropy surface. A pāhoehoe flow typically advances as a series of small lodes and toes that continually break out from a cooled crust.Basaltic Lava
Retrieved on 2008-02-13 It also forms

lava tube A lava tube, or pyroduct, is a natural conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow. If lava in the tube empties, it will leave a cave. Formation A lava tube is a type of lava ca ...

s where the minimal heat loss maintains low viscosity. However, there is also basaltic lava at the volcano characterized by a rough or rubbly surface composed of clinker called

ʻaʻā Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

. The clinkery surface covers a massive dense core, which is the most active part of the flow. As pasty lava in the core travels downslope, the clinkers are carried along at the surface.

17th-century eruption

The Tseax Cone was the source for a major lava flow eruption between 1668 and 1714 that travelled into the

, dammed it, and formed

Lava Lake Lava lakes are large volumes of molten lava, usually basaltic, contained in a volcanic vent, crater, or broad depression. The term is used to describe both lava lakes that are wholly or partly molten and those that are solidified (someti ...

. The flow subsequently travelled north to the

, where it filled the flat valley floor for an additional , making the entire lava flow approximately long. The Nass River valley contains abundant tree casts and

s. The tree casts were formed when the hot lava flow burned out tree trunks and left holes in the lava. Lava tubes formed when the low-viscosity hot alkali

ic lava travelled beneath the surface, which eventually flowed out and left the crust as the roof and walls of the tubes. Legends of the

Nisga'a The Nisga’a , often formerly spelled Nishga and spelled in the Nisga'a language as (pronounced ), are an Indigenous people of Canada in British Columbia. They reside in the Nass River valley of northwestern British Columbia. The name is a r ...

people tell of a prolonged period of disruption by the volcano, including the destruction of two Nisga'a villages. Several Nisga'a people dug pits for shelter but approximately 2,000 Nisga'a people died from

volcanic gases Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic ...

and poisonous smoke (most likely from

asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that can i ...

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

). The Nisga'a story of the destruction is Canada's worst known geological disaster. The lava beds, which reach above the road in some places, are the burial ground of these people. It is the only eruption in Canada for which legends of

First Nations First Nations or first peoples may refer to: * Indigenous peoples, for ethnic groups who are the earliest known inhabitants of an area. Indigenous groups *First Nations is commonly used to describe some Indigenous groups including: **First Natio ...

people have been verified.Geological Survey of Canada: Tseax Cone
Retrieved on 2008-02-13 The lava flow can also be found near modern Nisga'a villages, such as Gitlakdamix. This eruption is just one of hundreds that have modified the landscape of western Canada over the past million years. It has recently been suggested that the Tseax eruption was related to the Cascadia earthquake of 26 January 1700, which was the most powerful earthquake during the last 1000 years in the Pacific Northwest. Before the 17th century eruption, the Tseax Cone had erupted in 1325.Deadly Gases
Retrieved on 2008-02-13

Potential for a future eruption

Today, the

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

lies dormant within Nisga'a Memorial Lava Beds Provincial Park. Gases currently being emitted by the volcano are evidence that the volcano is still active and potentially dangerous. Signs of unrest such as

seismic activity An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

and increased gas output will almost certainly precede any future eruptive activity from the Tseax Cone. If the Tseax Cone were to erupt, its effects would be felt throughout the interior of British Columbia. There may be a repeat of the poisonous gas disaster that happened to the Nisga'a people during the last eruption. If the lava flows are voluminous enough, they could spark

forest fires A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identif ...

and dam local rivers, crippling the local ecosystem. This would have disastrous short-term consequences for the important salmon fisheries found along the

system. Further study and monitoring of the volcano is necessary in order to predict when the Tseax Cone might erupt, perhaps giving those living downslope and downwind the opportunity to evacuate, much like that which preceded the 1980 eruption of Mount St. Helens.

References

External links

Volcano World
* "Ignis: a Parable of the Great Lava Plain in the Valley of Eternal Bloom, Naas River, British Columbia (1918)

BCGNIS Geographic Name Details: Tseax Cone
{{Interior Mountains Cinder cones of British Columbia Rift volcanoes Natural disasters in British Columbia Nass Country Northern Cordilleran Volcanic Province 18th-century volcanic events Active volcanoes 18th-century natural disasters Nisga'a Hazelton Mountains Polygenetic cinder cones

Geology

17th-century eruption

Potential for a future eruption

See also

References

External links