Sometimes considered a subfeature of the Mount Washington shield volcano, Hoodoo forms one of several glaciated remnants of Pleistocene volcanoes in the region, other nearby examples including Maxwell Butte and Cache Mountain. It is a cinder cone and possesses an intact summit crater, since the neighboring andesite lava dome of Hayrick Butte prevented Pleistocene glaciers from reaching Hoodoo's summit. The crater is open to the east as a result of its irregular topography, which led to uneven distribution of ejected material such that most of the volcanic rock that forms the edifice was deposited elsewhere. The cinder cone is surrounded by volcanic ash from the Sand Mountain Cones that was moved by water, and some of this ash forms a layer on the floor of the summit crater.