Mount Defiance is a 5,584-foot summit in Washington’s Cascade Range within the Alpine Lakes Wilderness, west of Snoqualmie Pass in the Mount Baker-Snoqualmie National Forest. Its runoff feeds tributaries of the Snoqualmie River, and it rises among steep ridges, granite walls, glacially carved valleys, and numerous alpine lakes. The mountain shares the marine west coast climate of the western Cascades, bringing heavy winter precipitation, dense snow, avalanche danger, and clearer summers. Its setting reflects a long geologic history: the Cascades developed in the late Eocene through plate movement, volcanism, and terrane accretion, then Pleistocene glaciations sculpted the rugged landscape seen today.