Abstract

The Wetumpka impact structure, located in Elmore County, Alabama, was first described as an astrobleme in 1976, and research has continued to the present day. The present research project adds to the body of knowledge about Wetumpka because this work seeks to explain better the effects of hypervelocity impact upon a layered target where in poorly consolidated, clastic sedimentary strata are covering crystalline bedrock and the impact occurred in a marine environment. This study focuses on the formation and development of the western basement crater rim of the Wetumpka structure and how the impact affected the behavior and mechanics of these rocks during the explosive event. The current study includes: a complete descriptive analysis of drill core #09–01, which penetrates through the crystalline crater rim; a 3D resistivity survey on the western part of the rim, near the drill site, which reveals crystalline rim rock fractures in a detailed way; and maps and cross-sections derived from light detection and ranging (LiDAR) elevation data, which allow for very accurate construction of maps and cross-sections that can be used for interpretation of the surface and shallow subsurface geology of the impact structure. Specifically, LiDAR data with approximately 6.6-ft (2-m) resolution allows for construction of highly detailed digital elevation models (DEMs) and derivative images, which have been used in this study.