Using GIS to Evaluate an Enigmatic Diamicton in the Spring Mountains, Southern Nevada*

Abstract

The Spring Mountains are located in southern Nevada and lie along the western margin of the Las Vegas Valley. A diamicton located approximately 2,590 m (8,500 ft) above sea level in the Spring Mountains contains numerous striated limestone clasts ranging in size from 0.5 cm to 1.0 m. There are a variety of physical processes that can produce diamictons, and glacial geologists are often faced with the task of deciding what process controlled the formation of enigmatic diamictons. One characteristic distinctive to glacially derived diamictons is the presence of parallel surface striations on transported clasts. This study presents a GIS-based methodology used to evaluate surface striations on limestone clasts sampled from the Spring Mountain diamicton in southern Nevada. Using a combination of graphical software, ArcView GIS, and Avenue scripting, we streamlined the process of measuring and analyzing orientation values from individual surface striations. The results demonstrate a well-developed preferred orientation for clast striations and support our working hypothesis that the Spring Mountain diamicton is glacial in origin. If we accept a glacial origin, the presence of this deposit at 36° north latitude suggests the Spring Mountains represent the southernmost extent of Late Quaternary glaciation in the Great Basin. *We would like to acknowledge Dr. Nick Saines for discovering this deposit and recognizing the important implications for Spring Mountain glaciation. This project was supported by a grant from the University of Nevada, Las Vegas (UNLV) Graduate Student Association and a grant from the UNLV Office of Research. Scanning electron microscopy was conducted at the UNLV Electron Microanalysis and Imaging Laboratory (EMIL). We would like to thank the four reviewers of this manuscript for their useful comments and critiques.