Development of the Canadian River Valley in the Texas Panhandle resulted mostly from regional subsidence following dissolution of Permian bedded salts. Salts of the Clear Fork, Glorieta, San Andres, and Seven Rivers Formations have undergone dissolution along the margins of the Palo Duro, Dalhart, and Anadarko Basins. The Canadian River Valley follows a zone of subsidence for <208 km (130 mi) across the High Plains. High solute loads (3,000 ppm chloride) in the Canadian River and historical development of sinkholes indicate that dissolution and subsidence processes are still active. Evidence that these processes have been active in the region since the middle Tertiary includes Pliocene lake sediments and Quaternary terrace alluvium that have been deformed by dissolution-induced subsidence as well as former sinkholes filled with lacustrine sediments of the lower Ogallala Formation (Miocene).