Granitic Domes of the Mohave Desert, California

Several granitic areas in the Mohave Desert region of southeastern California have been degraded to smooth dome-like forms, to which Lawson has given the name, panfans. They have diameters of from 3 to 6 or 8 miles and heights of from 500 to 2,000 feet over the adjacent lower land. One of the best examples is shown in Plate 12. The well graded convexity of these masses, the steepest declivity of which seldom measures more than 4° or 5°, is flanked by the long, aggraded, concave slopes of their detritus. In some instances the domes are elongated into arches, 10 or 15 miles in length. Many other areas, granitic and non-granitic, less completely and less symmetrically degraded, exhibit bold or subdued residual forms surmounting their smoothly degraded flanks. The most perfect domes or arches result from the undisturbed degradation of upheaved granitic masses which have been worked upon, according to their original form, 1 chiefly by one or the other of two somewhat unlike erosional processes, both of which are merely modifications of ordinary erosional processes appropriate to the dry climate where their action takes place