The Four Craters Lava Bed Wilderness Study Area is divided into two distinctive types of land areas, each covering about half the acreage. The first type is the rugged lava flows and cinder cones. The second type is sagebrush/grassland flats. About half of the acreage in the WSA contains rugged lava flows and cinder cones. The remaining acreage is sagebrush/juniper and sagebrush/ grassland flats. The WSA contains the “Crack in the Ground,” a large tension fracture in the basalt approximately 2 miles long and from 10 to 70 feet in depth. This crack reaches a maximum width of about 20 feet. Another tension fracture, volcanic spires and pressure ridges also occur in the lava flow.
The WSA was studied under Section 603 of the Federal Land Policy and Management Act and was included in the Final Oregon Wilderness Environmental Impact Statement (EIS) filed in February 1990.