Also composed of basaltic andesite, the cone rises over the surrounding plateau. Black Butte is a striking feature just north of US Highway 20, which descends from the east flank of the Cascades. It is nearly symmetrical with a youthful profile, though it is actually older than any other visible High Cascades volcano. Black Butte is well-preserved due to a lack of glaciation east of the major Cascade arc. Black Butte has undergone mild erosion, with shallow ravines on its slopes, deep gullies on its sides, and rocks with weathering rinds. Black Butte forms a steep-sided volcanic cone, with an unexposed pyroclastic core and no summit crater. It is one of the larger mafic volcanic cones in the Oregon Cascades, with a volume of . Black Butte's composition is characteristic for the High Cascades, consisting of light to dark gray basaltic andesite rock with a fine to medium grain. The flanks of the volcano display outcrops of the lava, which are blocky and mixed with zones of breccia, suggesting the flows were slow-moving and were erupted from a central vent.