West Crater is a small andesitic lava dome in southern Washington’s Cascades, part of the Marble Mountain–Trout Creek Hill volcanic field south of Mount St. Helens in Gifford Pinchot National Forest. One of thirteen cones in the West Crater–Soda Peaks zone, it formed on the floor of a glacial cirque and has a summit crater with a visible remnant of lava at its base. The volcano likely built its dome and then produced at least two substantial Holocene lava flows that filled nearby canyons. Its deposits are interlayered with ash from Mount St. Helens and Mount Mazama, linking it to the broader volcanic history of the Pacific Northwest.