Upwarped mountains are generally the result of broad arching of the crust or sometimes great vertical displacement along a highangle fault. The Black Hills in South Dakota and the Adirondack Mountains in New York are upwarped mountain ranges. Volcanic mountains are the accumulations of large amounts of volcanic lavas and pyroclastic material around the volcanic vent, such as seamounts and stratovolcanoes. The Hawaiian and Aleutian Islands are volcanic mountains. Fault-block mountains result from tensional stress.