PRELIMINARY GIS EVALUATION OF GROUND MOVEMENT AT COOK LAKE, WYOMING

Cook Lake is a recreation area located approximately 15 miles north of Sundance, Wyoming in the Black Hills National Forest. Massive landslide activity has been documented at Cook Lake multiple years, including 1957, 1963/1964, and most recently in 1997/1998, the latter of which coincided with a record high precipitation year. The slides in this area often occur within the Morrison Formation, a failure-prone shale unit that dips downhill towards the lake. Due to recent higher-than-average precipitation and because this is an often visited public area, the safety of users is an important issue and land movement needs to be monitored.

This study will periodically survey nineteen monuments erected at Cook Lake with survey grade GPS. The positions of these monuments will be analyzed using ArcGIS software for any movement outside of known error tolerances. Data will also be analyzed alongside precipitation amounts from a nearby remote weather station. It is hypothesized if movement is detected that time periods with higher precipitation will show greater movement on the main slide body. This survey and analysis are the initial steps of investigation at the study area. Potential future investigations include LIDAR scanning, as well as drilling operations to better constrain the volume of the slide.