Several unusual breccia deposits occur in southern California, one of which is located immediately southeast of Bitter Spring in the Mojave Desert. The deposit is a megabreccia composed of metamorphic material of possible Pre-Cambrian age which rests upon Tertiary lake deposits. Both units are overlain by basalt flows estimated to be uaternary in age. The outcrops of breccia occur as large coherent blocks up to several thousand feet in length as well as less coherent breccias with large clasts. The origin of several of these breccia deposits has been under question. They are either sedimentary deposits, the results of gravity sliding, or tectonic deposits, the results of thrust faulting. This report concludes that the main portion of the Bitter Spring megabreccia is most likely a remnant of a thrust plate, while other portions appear to be gravity slide deposits.
