Problems of the Metamorphic and Igneous Rocks of the Mojave Desert

The Mojave Desert region, as defined by Baker (1911, pp. 335-336), is the region of desert plains, mountains, and valleys comprising the extreme southwestern portion of the Great Basin (fig. 1). It lies entirely within California, including parts of San Bernardino, Los Angeles and Kern Counties, and embraces an area of approximately 160,000 square miles. Its climate is arid, and the drainage is interior. Because much of the geology of this region is imperfectly known, any discussion of the regional aspects of the metamorphic and igneous rocks must take the form of a progress report. The relatively few published geological reports describe more or less widely separated areas, involve investigations of widely differing scales and qualities, and in general have not been coordinated parts of any broad, systematic program of research. Knowledge of the geology thus is peculiarly spotty, and some apparently critical areas and subjects have been completely neglected. Present knowledge provides a basis for some conclusions, but at the same time it points to numerous problems awaiting solution. This paper is written in an attempt to focus attention upon some of these interesting unsolved problems, as well as to collate the conclusions already reached by various workers.