Аннотация:Abstract. In 1992, during one and a half months the first two authors were engaged in field works in the southern Grea Basin, Province of Basins and Ranges, USA. This region is situated within the mountain belt of Central Cordilleras divided into two parts: western eugeosynclinal (Sierra Nevada mountains) and eastern miogeosynclinal (Province of Basins and Ranges) areas. On the east, the mountain belt here adjoins the Colorado Plateau, a part of the North American platform. The region of our observations lies in the miogeosynclinal part of the belt, immediately east of the Death Valley (Fig.1). Moreover, reconnaissance routes were made farther to the east, in the Spring Mountains ridge and vicinities of the Grand Canyon, Colorado Plateau (Fig. 8).