The majority of the nearly long up-thrust formation called the Waterpocket Fold—a rocky spine extending from Thousand Lake Mountain to Lake Powell—is preserved within the park. Capitol Reef is an especially rugged and spectacular segment of the Waterpocket Fold by the Fremont River. The park was named for its whitish Navajo Sandstone cliffs with dome formations—similar to the white domes often placed on capitol buildings—that run from the Fremont River to Pleasant Creek on the Waterpocket Fold. Locally, reef refers to any rocky barrier to land travel, just as ocean reefs are barriers to sea travel.