The Desert Project: An Analysis of Aridland Soil-Geomorphic Processes

In 1957 the U.S. Soil Conservation Service initiated the Desert Soil-Geomorphology Project astride the Rio Grande Valley near Las Cruces, New Mexico. At that time, little was known about soils in arid and semiarid regions of the American Southwest away from alluvial valley floors. This study was undertaken to learn more about the morphology, classification, genesis and occurrence of desert soils and their relation to late-Cenozoic landscape evolution, and to assist in understanding, classifying, and mapping soils in similar geomorphic settings elsewhere. The hallmark of this investigation was the integration of classic pedologic and geologic approaches in the study of a desert and semidesert soil-geomorphic system. The 1024 km2 (400 mi2) site for the Desert Project was located in the Rio Grande Valley area of the southeastern Basin and Range province because it supplied many of the requirements of the study. First, this part of southern New Mexico is typical of large parts of the Southwest in terms of terrain, parent material, soil age, and general climatic history. Second, distinctly different soils formed on various landforms and parent materials. For example, the area contains a river valley as well as intermontane-basins with internal surface drainage, so that soils and landscapes of each could be compared. In addition, the area has both noncalcareous parent materials (e.g., rhyolite) and highly calcareous parent materials (e.g., limestone). Third, the area contains both semiarid mountains and arid basins, thus making it possible to study the effects of climatic and vegetation differences on soils and landscapes of the same age. Fourth, the area contains soils that range widely in age, from less than 100 years old to more than 2,000,000 years old. This presentation will summarize some of the major findings of the Desert Project about desert soils and geomorphology.