DIGITAL DEPTH TO BEDROCK MAP OF MISSOURI

Depth to bedrock information in multiple digital formats is an integral part of evaluation for geothermal energy development. Depth to bedrock in Missouri varies greatly across the state, ranging from zero to 25 feet in the central and southeastern regions to as deep as 325 feet in the extreme northwestern corner of the state. The northern and Bootheel regions of Missouri have deeper bedrock depth, generally ranging from 175 to 300 feet. Bedrock depths between zero and 10 feet can be found statewide, but are predominant in the central region.

Development of a depth to bedrock map for Missouri involved production of digital data in various formats as part of creation of the final published map. Geologically appropriate data from Missouri Department of Natural Resources, Geological Survey Program’s digital files for certified water wells and water well strip logs were evaluated for accuracy, spatial distribution and data variation. The depth to bedrock map was based on the first bedrock unit noted in well records that contained surficial material information, creating the first digital data set. A raster interpretation was generated from the depth data using ArcMap^TM 10, ESRI Spatial Analyst Extension, and acted as the second digital data set. Contours were generated from the raster data set at 10-foot intervals, forming the third digital data set. The final digital data set created was the data for the final published open file map. Availability of these four digital data sets increases usability of the data for users with varying needs. Preservation of the files related to each stage allowed data to be used for other projects, such as liquefaction hazards maps, without requiring arduous reinterpretation of the original data.