 The refuge is situated within the Channeled Scablands, an area formed 16,000 years ago by Missoula Floods during the last ice age.The powerful forces of volcanism, glaciation, and the largest flood in geological history have combined to forge a distinct environment.Refuge ecosystems represent an ecological transition between the dry, sagebrush-dotted grasslands of the Columbia Basin up toward the timbered Selkirk and Bitterroot mountain ranges that rise up to the east.