Like other volcanic landforms in British Columbia, Black Dome Mountain is part of the Pacific Ring of Fire which includes over 160 active volcanoes. There are obsidian deposits and other deposits around the volcano. It has produced olivine basalt dykes, lavas, and agglomerate. Black Dome Mountain is thought to have formed as a result of extension of the crust behind the Cascadia subduction zone and last erupted during the Pliocene.