Antelope Canyon is a slot canyon in the American Southwest, on Navajo land east of Page, Arizona. It includes two separate canyon sections, referred to as Upper Antelope Canyon (or The Crack), and Lower Antelope Canyon (or The Corkscrew). Antelope Canyon was formed by erosion of Navajo Sandstone due to flash flooding and other sub-aerial processes. A flood occurred October 30, 2006 that lasted 36 hours, and caused the Tribal Park Authorities to close the Lower Antelope Canyon for five months. Rainwater during the monsoon season runs into the extensive basin above the slot canyon sections, picking up speed and sand as it rushes into the narrow passageways.