Slopes are steep and stream drainages are deeply incised.
When established in 1948, it was unroaded virgin forest and about two-thirds remain pristine today. Broadly representative of the rugged mountainous landscape of the Pacific Northwest, it contains excellent examples of the region's conifer-dominated forest and stream ecosystems. Intra-site climatic variation is typical of mountainous terrain. Temperature varies with elevation, aspect and topographical shading. Temperature inversions are common.