Ground‐water dams created by faulting of alluvial sediments in the hurricane fault‐zone, Utah

Ground‐water dams are recognized in the unconsolidated sediments of two intermontane valleys in southwestern Utah. Parowan Valley is about 30 miles long and has a general northeasterly trend; Cedar City Valley lies west and south of Parowan Valley, is somewhat larger, and has a more nearly north‐south trend. Great accumulations of boulders, gravel, sand, and clay have been brought into both valleys by the streams that drain the surrounding highlands, and the valleys have become topographic basins whose lowest parts are occupied by lakes or dry alkali flats, rimmed on all sides with the alluvial fans and cones that have been formed by the streams tributary to the valleys. Ground‐water occurs principally in these unconsolidated sediments, and in both valleys a large proportion of the irrigated lands is dependent upon water pumped from wells.