Hoodoo Mountain

Stratovolcano in British Columbia, Canada
the mountain in British Columbia

Hoodoo Mountain, sometimes referred to as Hoodoo Volcano, is a potentially active stratovolcano in the Northern Interior of British Columbia, Canada. It is located northeast of the Alaska–British Columbia border on the north side of the Iskut River opposite of the mouth of the Craig River. With a summit elevation of and a topographic prominence of , Hoodoo Mountain is one of many prominent peaks within the Boundary Ranges of the Coast Mountains. Its flat topped summit is covered by an ice cap more than thick and at least in diameter. Two valley glaciers surrounding the northwestern and northeastern sides of the mountain have retreated significantly over the last hundred years. They both originate from a large icefield to the north and are the sources of two meltwater streams. These streams flow along the western and eastern sides of the volcano before draining into the Iskut River. Much of Hoodoo Mountain was formed beneath glacial ice and it has been overlain by glaciers or an ice cap throughout much of its history. The main rock types composing the volcano are phonolite and trachyte, which were deposited during six periods of eruptive activity beginning about 85,000 years ago. Most of these eruptive periods were characterized by steady flows of lava but at least one period of explosive activity occurred as indicated by the presence of pyroclastic rocks. The latest eruptive period began about 10,000 years ago with the eruption of extensive lava flows that cover the north–central, northwestern and southeastern mountain slopes. A lava flow covering the southwestern slope may have been produced by a more recent eruption within the last couple of hundred years. Although no historical eruptions are known at Hoodoo Mountain, there have been periods of seismic activity since at least the mid 1980s, indicating possible future eruptions and volcanic hazards. Hoodoo Mountain lies in a remote area of Cassiar Land District that has undergone mineral exploration since at least the early 1900s. This exploration led to the discovery of copper, silver and gold within the Iskut River floodplain where two underground mines operated between 1988 and 1999. Geological studies have been conducted at Hoodoo Mountain since at least the 1940s; the most detailed studies occurred in the 1990s and 2000s. The area has a mostly cool and wet climate with heavy precipitation. As a result, a limited number of mammals live around Hoodoo Mountain. Trees of the pine and willow families form forests in the regional river valleys and on the lower slopes of the volcano. They compose one of many ecoregions that occur throughout British Columbia. Due to its remoteness, Hoodoo Mountain can only be accessed by air, by water or by trekking great distances on foot. The closest communities are more than away from the mountain.

Hoodoo Mountain lies within the Boundary Ranges Ecoregion, a mountainous region of the Coast Mountains in southeastern Alaska and northwestern British Columbia characterized by rugged, largely ice capped mountains of granitic and metamorphic rocks. Mountain hemlock, western hemlock and Sitka spruce form forests on valley bottoms and lower valley slopes. They are overlooked by an extensive alpine tundra zone consisting primarily of large icefields, glaciers and barren rock. A limited number of mammal species thrive in this ecoregion, such as hoary marmots and mountain goats, which inhabit the alpine tundra zone. The Boundary Ranges Ecoregion is part of the Coast and Mountains Ecoprovince which forms part of the Humid Maritime and Highlands Ecodivision.

Hoodoo Mountain has a maritime glacial climate that is intermediate between fully coastal maritime and continental climates. Moist air from the Pacific Ocean brings intense precipitation over the region while simultaneously allowing cold Arctic air to pass down through the Portland Canal into the Dixon Entrance where it flows into British Columbia's North Coast.

Two valley glaciers wrap partially around the base of Hoodoo Mountain, both of which are actively retreating. Hoodoo Glacier surrounding its northwestern base is the source of the Hoodoo River which flows south into the Iskut River. Several changes have taken place at this double lobed glacier since the 1920s. Its terminus has retreated about , having formerly flowed around both sides of a north–south trending ridge. A small moraine dammed lake lies along the southwestern margin of Twin Glacier. Hoodoo Glacier and Twin Glacier are separated by a ridgeline extending north of Hoodoo Mountain.

Hoodoo Mountain is part of the Northern Cordilleran Volcanic Province (NCVP), a broad area of shield volcanoes, lava domes, cinder cones and stratovolcanoes extending from northwestern British Columbia northwards through Yukon into easternmost Alaska. The dominant rocks comprising these volcanoes are alkali basalts and hawaiites, but nephelinite, basanite and peralkaline phonolite, trachyte and comendite are locally abundant. These rocks were deposited by volcanic eruptions from 20 million years ago to as recently as a few hundred years ago. The cause of volcanic activity in the Northern Cordilleran Volcanic Province is thought to be due to rifting of the North American Cordillera driven by changes in relative plate motion between the North American and Pacific plates. Hoodoo Mountain is part of a subdivision of the NCVP called the Stikine Subprovince. This subprovince, confined to the Stikine region of northwestern British Columbia, includes three other volcanic centres: Heart Peaks, Level Mountain and Mount Edziza. The four volcanic centres differ petrologically and/or volumetrically from the rest of the NCVP. Heart Peaks, Level Mountain and Mount Edziza are the largest NCVP centres by volume, the latter two of which have experienced volcanism for a much longer timespan than any other NCVP centre. Hoodoo Mountain, Level Mountain and Mount Edziza are the only NCVP centres that contain volcanic rocks of both mafic and intermediate to felsic which represent the earliest known manifestations of Quaternary magmatism in the Iskut region. This is because it has a different lithological and topographical structure than most glaciated mountains in the Canadian Cordillera. In contrast to its rugged counterparts, Hoodoo Mountain is symmetrical and circular in form. The Monument on the southwestern side of Hoodoo Mountain is a vertical rock column that reaches more than in height. It is the eroded remains of a volcanic vent that was fed by a west trending dike. Hazards stemming from renewed volcanism are lava flows and flooding, as well as fallout from explosive eruptions. Lava flows generated by effusive eruptions could dam the Iskut River and pose a major hazard to mining operations upstream due to rising waters. Like other volcanoes in the NCVP, Hoodoo Mountain is not monitored closely enough by the GSC to ascertain its activity level. The Canadian National Seismograph Network has been established to monitor earthquakes throughout Canada, but it is too far away to provide an accurate indication of activity under the mountain. It may sense an increase in seismic activity if Hoodoo Mountain becomes highly restless, but this may only provide a warning for a large eruption; the system might detect activity only once the volcano has started erupting. If Hoodoo Mountain were to erupt, mechanisms exist to orchestrate relief efforts. The Interagency Volcanic Event Notification Plan was created to outline the notification procedure of some of the main agencies that would respond to an erupting volcano in Canada, an eruption close to the Canada–United States border or any eruption that would affect Canada.

The volcanic deposits at Hoodoo Mountain were briefly described in 1948 by F. A. Kerr of the Geological Survey of Canada (GSC) while studying the regional geology along the southern part of the Iskut River. This included mapping of the shape of the summit ice cap using ground penetrating radar and ice radar, as well as the production of a preliminary hazard assessment for the Iskut area. Analysis of data indicated the absence of a caldera or large crater beneath the ice cap. Instead, the underlying topography was shown to be characteristic of an inverted and very shallow saucer. The use of radars to penetrate the ice cap and to assess the subglacial topography proved to be instrumental for studying other glaciated volcanoes in the American Cordillera and elsewhere. Personnel involved in the 1997 expedition were Catherine Hickson and Mark Stasiuk of the GSC, Jim Nicholls of the University of Calgary, Jeff Schmok and Guy Cross of Golder Associates, Alison Rust, Ben Edwards and Kelly Russell of the University of British Columbia, and Trevor Page of Lancaster University. Exploration of the Pickaxe Vein by Skyline Gold began in 1980 to define its gold potential. This was followed by the discovery of the Discovery Vein in 1981, which led to further drilling and the discovery of a high grade gold vein in 1982 that became known as the 16 Vein. Surveying, drilling and trenching was carried out by Skyline Gold, Placer Development and Anaconda Canada Exploration between 1982 and 1988. The Johnny Mountain Mine commenced production in November 1988 after having been engaged in pre production since January of that year. This small underground mine operated until August 1990 when high operating costs and low gold prices forced it to shut down. This was followed by closure of the ore mill in September of that year. The mine remained closed until 1993 when further mining and milling took place. A total of 196,358 tonnes of ore was mined from 1988 to 1993, from which of copper, of silver and of gold was recovered. Intermittent mineral exploration has taken place at the Johnny Mountain Mine since its closure in 1993. The Snip Mine, owned jointly by Cominco and Prime Resources, began production in January 1991. An airstrip was used continuously to ship ore concentrate from the mine until May 1999 when all mining operations ceased. Production throughout the mine's lifespan amounted to of copper, of gold, and of silver from 1.2 million tonnes of ore mined. Mineral exploration has occurred at the Snip Mine intermittently since its closure in 1999. The mountain can also be approached from the Alaskan community of Wrangell by boating up the Stikine and Iskut rivers.