West Crater is a small lava dome, made up of andesitic lava with two large lava flows. It is not highly prominent. The volcanic edifice has a ridge of Tertiary volcanic and intrusive rock, which lies on the southern edge of West Crater. West Crater's dome reaches an elevation of , with a diameter of . It has a summit crater with a width of and a depth of . The dome still possesses a lobe of lava at the bottom of this summit crater. West Crater's lava dome formed on the floor of a glacial cirque, and has a similar size to the lava dome formed after the 1980 eruption of Mount St. Helens.