Mount Edziza
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| Mount Edziza | |
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 Mount Edziza as seen from the Stewart-Cassiar Highway |
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| Elevation | 2,787 m (9,144 ft) |
| Location | British Columbia, Canada |
| Range | Tahltan Highland |
| Prominence | 1,750 m (5,741 ft) |
| Coordinates | |
| Topo map | NTS 104G/10 |
| Type | Shield volcano, Stratovolcanoes |
| Volcanic arc/belt | Northern Cordilleran Volcanic Province |
| Age of rock | Miocene-to-Holocene |
| Last eruption | 1340 BP |
| Listing | List of volcanoes in Canada |
Mount Edziza is a potentially active volcanic massif in the Stikine Country of northwestern British Columbia, Canada. The volcano and the surrounding area are protected within Mount Edziza Provincial Park. It has an area of 1,000 km2 and consists of a complex of multiple peaks and ridges, with several glaciers flowing in all directions. The summit is topped by an ice-filled caldera, which is almost 2 kilometres (1 mi) wide, and has produced more than 8 million years of nearly continuous volcanic activity. The three main peaks around the caldera are the southwest summit, the southeast summit and the north summit. This is the second largest area of volcanic activity in the Northern Cordilleran Volcanic Province after the Level Mountain Range, as well in Canada.
Mount Edziza is Canada's highest volcano at 2,787 metres (9,144 ft). However, Mount Silverthrone in southwestern British Columbia, has a height of 2,865 m (9,400 ft) and might be the highest volcano in Canada. But it has never been determined if Silverthrone's 2,865 m high point is actually volcanic rock or not (it is covered by snow and ice), making Mount Edziza the highest confirmed volcano in Canada.[1]
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[edit] History
As early as 10,000 years ago, the Tahltan people, who now live in Dease Lake, Telegraph Creek and the Iskut, used obsidian from Mount Edziza to make tools and weapons for trading material. This is the main source of obsidian found in northwestern British Columbia, which was traded as far away as Alaska and northern Alberta.[2] Obsidian is a type of naturally occurring glass that is highly valued for its cutting qualities. Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic conchoidal fracture, creating razor sharp edges.
More recently, most of the plateau was made into the Mount Edziza Provincial Park to preserve the volcanic and culture treasures unique to the northern British Columbia area. It encompasses over 230,000 hectares of the Tahltan Highlands. There is no vehicle access to the park, and there are only a very few basic facilities.
[edit] Geology and eruptive history
Mount Edziza is perhaps the most spectacular volcanic edifice in British Columbia. The complex comprises a large volcanic plateau (65 km (40 mi) long and 20 km (12 mi) wide) made of predominantly basaltic lava flows from the massive shield volcano of Mount Edziza with four large stratovolcanoes built on top of the plateau.[3] The central, highland region of the plateau is largely underlain by more felsic lavas (trachyte and rhyolite). The associated lava domes and satellite cones were constructed over the past 7.5 million years during five magmatic cycles beginning with eruption of alkali basalts and ending wth felsic and basaltic eruptions as late as 1,340 years ago. The blocky lava flows still maintain their original forms. The complex has been an area of long-lived volcanic activity for the past 7-10 million years. The Desolation Lava Field is the northernmost end of the plateau. It covers an area of over 150 km² and is the largest area of the youngest lava flows. The longest lava flow is about 12 km (7 mi) long. The plateau has been an important cultural resource.
Numerous eruptions have occurred within the last 10,000 years including: Desolation, Mess Lake, Snowshoe Lava Field, Kana Cone, Cinder Cliff, Icefall Cone, Ridge Cone, Williams Cone, Walkout Creek and the well-preserved Eve Cone.[3] Many ice-contact features and products of subglacial eruptions are found in the Mount Edziza complex. More than 30 Holocene cinder cones, primarily of basaltic composition, are located on Mount Edziza and the adjacent Spectrum Range, some of which are younger than about 1,300 years. Large areas of Holocene lava flows of the postglacial Big Raven Formation are located north of Mount Edziza, forming the Desolation Lava Field, and south and southwest of Ice Peak, forming the Snowshoe Lava Field. Many of the volcanic features in the volcanic complex are protected as part of Mount Edziza Provincial Park, one of the larger provincial parks in British Columbia.
The 7.5 million year old Armadillo Peak stratovolcano at the south end of the complex is overlapped by the Ice Peak central volcano, which was formed during the early Pleistocene, and contains a caldera largely destroyed by glaciers. The Mount Edziza stratovolcano on the north was formed about 1.0-0.9 Ma. The 2 kilometres (1 mi) wide, ice-filled caldera truncates its summit; lava domes were subsequently emplaced around its periphery and lava lakes ponded within the caldera and overflowed its rim.[4]
Deposits at Mount Edziza indicate that the volcano has a history of producing not only fluid and relatively passive basaltic lava flows, but also more silica-rich trachytic lava flows, rhyolitic lava flows and explosive eruptions for the last 7-10 million years. The silica-rich compositions are similar with the most violent eruptions on Earth.[5] A large explosive eruption from Mount Edziza could produce an ash plume that would affect the northwestern part of Canada. Track Bench pumice deposit emphasizes one of the significant volcanic hazards related with the Mount Edziza volcanic complex - the likelihood of a great, explosive eruption. Mount Edziza and other nearby volcanoes to the north have also blocked the Stikine River by lava flows in the past.[5]
[edit] Recent activity
The most recent activity at the Mount Edziza complex have been warm springs, several of which are found on Mount Edziza's western flank, including Elwyn springs (36°C), Taweh springs (46°C), and inactive springs near Mess Lake. The springs are near the youngest lava fields on the plateau and are probably associated with the most recent volcanic activity at the Mount Edziza complex.
Hot springs are closely associated with fumaroles. Generally the water is circulating groundwater that comes into contact with hot rocks and finds outlets to the surface. Composition of the springs depends both on the rocks the water has passed through and the abundance of volcanic emanations mixed with the groundwater. Iron oxide, iron sulphides and other substances often colour pools of boiling mud brilliant yellow, red, brown or green. Hot springs containing considerable dissolved silica may deposit it to form siliceous sinter, whereas those containing dissolved calcium carbonate deposit calcareous tufa. Overflow of the springs may build mounds, spires or stepped terraces of sinter or tufa.
Mount Edziza is one of the top 11 Canadian volcanoes appear related to seismic activity since 1975, the others include: Castle Rock, Hoodoo Mountain, Lava Fork Valley, Crow Lagoon, Mount Silverthrone, Mount Cayley, Mount Meager, Wells Gray-Clearwater Volcanic Field, Mount Garibaldi and Nazko Cone.[6] Although the existing data do not allow a clear conclusion, these observations are further indications that some of Canada's volcanoes are potentially active, and that their associated hazards may be significant. It is noteworthy that the seismic activity correlates with some of Canada's most youthful volcanoes, and with long-lived volcanic centers with a history of significant explosive behavior, such as Mount Edziza.
[edit] Mount Edziza Volcanic Field
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[edit] See also
- List of volcanoes in Canada
- Mount Edziza Provincial Park and Recreation Area
- Mountain peaks of Canada
- Mountain peaks of North America
- Northern Cordilleran Volcanic Province
- Volcanism in Canada
- Geology of the Pacific Northwest
[edit] References
- ^ Mount Edziza in the Canadian Mountain Encyclopedia. Retrieved on 2007-10-11
- ^ Journey & Transformations: British Columbia Landscapes Retrieved on 2007-10-11
- ^ a b Volcano World Retrieved on 2007-10-10
- ^ Smithsonian Institution Global Volcanism Program: Mount Edziza Retrieved on 2007-10-10
- ^ a b Natural Resources Canada Retrieved on 2007-10-10
- ^ Volcanoes of Canada Retrieved on 2007-10-10
[edit] External links and sources
- Mount Edziza is at coordinates Coordinates:
