Hoodoo Mountain - Geography and Geology

Geography and Geology

Hoodoo Mountain lies on the southern axis of the Northern Cordilleran Volcanic Province, a large line of volcanoes extending from the Alaska-Yukon border to a point near Prince Rupert, British Columbia. The region in turn is part of the Pacific Ring of Fire, a seismically active region that encircles the Pacific Ocean and contains some of the world's most active volcanoes. The Northern Cordilleran Volcanic Province is produced by continental rifting as the Pacific Plate slides northward along the Queen Charlotte Fault, on its way to the Aleutian Trench, which extends along the southern coastline of Alaska and the adjacent waters of northeastern Siberia off the coast of Kamchatka Peninsula. As the continental crust stretches, hot magma rises and the near-surface rocks fracture along steeply graduated cracks parallel to the rift known as faults. Like many other rift-related volcanoes, Hoodoo Mountain generates passive and occasionally explosive eruptions. Hoodoo Mountain is one of the three large compositionally diverse volcanoes of the Northern Cordilleran Volcanic Province along with the Mount Edziza volcanic complex and Level Mountain Range.

The overall flat-topped topography of Hoodoo Mountain led Canadian volcanologist Jack Souther to refer Hoodoo Mountain as a tuya, which are flat-topped, steep-sided subglacial volcanoes formed when lava erupts through a thick glacier or ice sheet. However, Hoodoo Mountain does not fit the normal tuya model because of its complex layering of rocks, although Hoodoo's unusual structure obviously results from frequent interactions between volcanic activity and Pleistocene ice sheets over the past 100,000 years.

Hoodoo Mountain contains at least two sets of prominent cliffs, producing a discontinuous, step-like topographic profile. The base of Hoodoo Mountain is largely delimited by a series of cliffs that range from 100 m (328 ft) to 200 m (656 ft) high, while Hoodoo's southeastern flank is relatively gentle. Here, lava flows from the most recent volcanic activity cover earlier topography; the southeastern flank is smooth from around the summit to the Iskut River. The top of the lower cliff ring defines a broad bench with an elevation of about 1,000 m (3,281 ft) that terminates against an upper set of cliffs. The seconed set of vertical cliffs is between 50 m (164 ft) and 100 m (328 ft) high and surrounds the summit. A prominent dike, known as The Monument, rises more than 100 m (328 ft) in elevation on Hoodoo's southwestern flank and is the remnants of a volcanic vent surrounded by thick deposits of lava and breccia formed during subglacial eruptions.

Hoodoo Mountain lies in an area of high elevation ecosystems colonizing very erodible substrate. The mountain is generally poorly forested due to its high altitude and remote alpine location. This mountainous terrain has made Hoodoo Mountain a site for alpine tundra. Even though alpine tundra lacks trees, Hoodoo's lower flanks contain mountain hemlock. Because alpine tundra is located in various widely-separated regions on Earth, there is no animal species common to all areas of alpine tundra.