After we entered Crater Lake National Park, we drove across the Pumice Desert. It's "a flat, open area that conspicuously contrasts with the surrounding forest of lodgepole pine (Pinus contorta). A wedge-shaped opening about 5-1/2 square miles in size, the Pumice Desert is covered with material ejected from ancient Mount Mazama. Gaseous materials filled the valleys and depressions surrounding the flanks of the mountain. The depths of deposits covering the Pumice Desert may be some 200 feet thick."