Volcano Mountain is located immediately north of the junction of the Pelly and Yukon rivers, half way between Whitehorse and Dawson City, central Yukon Territory. The volcano comprises a cinder cone and a series of lava flows that issued through breaks in the cone wall both to the northeast and the southwest. The northeastern lava flow travelled about 5.5 km and the southwestern flows, only about 3 km. The lavas at Volcano Mountain represent a unique type of lava, called 'olivine nephelinite', that is very uncommon in the geological record. These lavas are generally thought to have come from much deeper in the Earth than the basalt magmas common to most of the other young volcanoes in northwestern British Columbia and the Yukon Territory. They are also unusual because they contain small, angular to rounded fragments (nodules) of rock that come from the mantle, below the Earth's crust. These green nodules are called 'peridotites' because they are composed predominantly of the mineral olivine or, in gem form, 'peridot'. These lavas and the nodules they contain are similar to those erupted in the Wells Gray area of British Columbia.

The fluid nature of the lavas and the lack of significant fragmental material erupted from Volcano Mountain suggest that any future eruptions would probably be dominated by lava flows, with little to no explosive activity. Thus, the main hazards posed by any renewed activity include forest fires started by the hot lavas. However, evidence from older volcanic deposits immediately south of Volcano Mountain, in the Fort Selkirk area, indicates that lava flows may have once partly blocked or at least altered the course of the Yukon and Pelly rivers. Renewed activity in this area could disrupt the course of one or both of these major rivers and have a serious impacts on people living or working downstream.