Gravity and seismic measurements have outlined a deep subsurface trough, bounded throughout the greater part of its length by steep faults. Depths to the bedrock floor along the central part of the valley range from 3,000 to 9,000 ft. below the surface. The subsurface trough is divided into 2 parts, a narrow channellike depression near Lone Pine bounded by NW.-trending faults, and a broad basin at Owens Lake bounded by a more complex series of border faults. The bedrock ridge that crops out to form Alabama Hills is shown to extend from Independence to the N. edge of Owens Lake, nearly twice its visible extent. The main direction of faults that have formed the valley is NW.; subsidiary faults trend N., NE., and E. A fairly sharp velocity boundary within the Cenozoic valley deposits suggests a change in the rate and character of deposition which was probably the result of renewed uplift in the nearby mountains.