Cima Dome
Map SatelliteCima Dome is a granitic structure some 13 kilometers (8 miles) in diameter and is the remnant of an extensive late Pliocene erosion surface, Mesozoic rocks, primarily granitic, were eroded in the late Pliocene to an exceptionally smooth low relief essentially because of the homogeneity of the coarse quartz monzonite being eroded. In the early Pleistocene, pyroclastics and lavas were extruded over portions of the surface; subsequently a gentle deformation produced a broad warping which here led to a symmetrical, dome-shaped uplift. Due to the upwarping, increased erosion stripped away up to 30 meters (100 feet) of the volcanic materials and the slopes of the dome were converted to smoothly graded concave surfaces. Later, perhaps recent, volcanics have not affected the dome.
A dense Joshua tree forest of the uncommon Yucca brevifolia var. jaegeriana covers much of the dome. This forest is outstanding because of the denseness of the stand, its extent and good reproduction. There is also the characteristic Joshua tree woodland shrub association which includes Salazaria mexicana, Lycium spp., Coleogyne, Yucca baccata, Opuntia (3) spp., Tetradymia, Salvia dorrii, etc.
Integrity: There has been some reduction in the reproduction of the Joshua trees because of current use of the area for grazing.
Use: Educational, research, observational, light recreation.
Ref: Sharp, Robert P. 1954. The Nature of Cima Dome in Geology of Southern California. California Division of mines Bull. 170.
August 1975
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman
