Hoodoo Mountain is a massive but gently-sloped volcano in the Boundary Ranges associated with the Northern Cordilleran Volcanic Province. It is located in the Regional District of Kitimat-Stikine, about northeast of the town of Wrangell and on the north side of the Iskut River. The main flat-topped summit has an icecap in diameter and throughout its history the volcano has been influenced by glacial ice, including several periods of subglacial eruptions.
Hoodoo Mountain consists of lavas and some pyroclastic rocks which underwent six cycles of activity. The first cycle of volcanism occurred 85,000 years ago during the Pleistocene period, producing aphanitic lava flows, domes, and breccia deposits. The second eruptive cycle 80,000 years ago was manifest as a series of aphanitic lava flows that formed massive cliffs at low elevations near the base of the volcano. Pyroclastic deposits, up to thick on the north and west sides of the volcano were the third phase of activity between 80 and 54 thousand years ago, indicating at least one period of explosive volcanic activity. Aphanitic lava flows erupted about 54,000 years ago directly on top of the pyroclastic deposits. Between 54 and 30 thousand years ago, volcanism produced two distant types of lava-breccia associations, one between 54 and 40 thousand years ago, and the other probably slightly younger, between 40 and 30 thousand years old. The final eruptive cycle produced highly porphyry lava flows on the northwest and southwest sides of the volcano about 9 and 7 thousand years ago and are largely unglaciated. Hoodoo Mountain is considered active and could erupt in the future.
Volcanism at Hoodoo Mountain is caused by the rifting of the Earth's crust where two parts of the North American Plate are breaking apart. The cause of this rifting is the result of the Pacific Plate sliding northward along the Queen Charlotte Fault, on its way to the Aleutian Trench.
Hoodoo Mountain is currently in an area mined for minerals such as wollastonite, gold and there are several large mining camps within 15 km of its southern flank, although the trachytic rocks of the volcano are not presently known to host any mineral deposits.