undergraduate research

Geological mapping of the late Cretaceous to early Eocene strata within the Indian Creek
Area, Buffalo Gap National Grasslands, South Dakota.

Garrett Williamson, Dr. David Schmidt, and Dr.Tim Walsh, Wayland Baptist University.

During the summer field season of 2012, it was recognized that a detailed geologic map of the Indian Creek area within the Buffalo Gap National Grasslands of South Dakota could be established. According to current knowledge, no detailed geologic map of the permitted field area has been published. Therefore, a preliminary map that includes members (Ahearn, Crazy Johnson, and Peanut Peak) of the Chadron Formation as well as the Chamberlain Pass and Pierre Shale Formations has been constructed. Each member and formation were located, measured, lithologically described, and compared to previous interpretations. Other collected data consisted of coordinates and elevations between stratigraphic boundaries. This information was acquired using a Trimble Geo XH with Terrasync 5.30 software. Once field data was transferred into ArcGIS 10.0, a map scale of 1:8000 was selected to show detail covering an area of 1.4 km2. The data was overlaid with Digital Raster Graphs (DRG) and Digital Orthophoto Quarter Quadrangles (DOQQ). Contact lines of stratigraphic boundaries were digitized through coordinate points and correlated with surface topography to create a current geologic map. A detailed map of discernible stratigraphic units within the Indian Creek area will be a valuable tool for future paleontological and geological investigations. Since, more information is needed to cover the entire designated field area of 9 km2, field work will continue in the summer of 2013 to obtain the necessary data for completion of this project.


A taxonomic and taphonomic description of an ungulate fossil from the Chadron Formation of the Buffalo Gap National Grasslands, South Dakota.

Hunter Green and Dr. David Schmidt, Wayland Baptist University.

In a recent field expedition to the Indian Creek area within the Buffalo Gap National Grassland, South Dakota, a field team from Wayland Baptist University collected fossil specimens from the White River Group. This area is recognized as one of the most fossiliferous localities spanning late Cretaceous to early Miocene strata. A partial mandible of a large fossil ungulate was recovered from the upper Chadron Formation and is being investigated for its taxonomic relationship and condition of preservation. A preliminary description and morphometric analysis has been conducted on recovered skeletal elements. The left dentary is highly fractured and measures 30.7 cm in length and 9.2 cm diagonally from the angular process to the curved antero-dorsal margin of the ramus, approximately 3 cm behind molar 2. Additionally, the left dentary contains an incomplete tooth row that measures 13.7 cm in length consisting of molars and premolars. The right dentary is represented by several bone and tooth fragments with an incomplete dentition while possessing enough material for a partial description. Based on dental and skeletal morphological comparisons to other large ungulates from the Chadron formation, Brontotheriidae and Hyracodontidae families are currently considered for taxonomic assignment. Most of the observed fractures in the left dentary appear to have occurred after fossilization. However, bone weathering and fracturing prior to fossilization is indicated by fracture-filling clay and flakes of bone within the matrix.

Depositional interpretation using integrated sedimentological and paleontological data from a fossil-bearing unit within the Blackwater Draw Formation, Plainview, Texas.

Taryn Shadden, David Schmidt, and Bryan Steffen, Wayland Baptist University.

Sediments of a fossil-bearing layer within the Blackwater Draw Formation are exposed in an abandoned quarry wall inside the city limits of Plainview, Texas. These sediments were previously interpreted as being deposited in an ancient stream channel by fluvial processes. This layer was horizontally sampled at three locations (PS 1, 2, and 3) to investigate if sediment deposition was restricted to stream flow. Several criteria were used to determine deposition of sediments, including 1) minerals present, 2) size of grains, and 3) taxonomic variation of fossil molluscs (bivalves and gastropods). Mineral grains consist primarily of quartz sands with minor amounts of calcite and feldspar. Samples PS 1 and 2 contain coarse grained cross-beds, and mollusc biodiversity which indicate deposition by stream flow. Location PS 3 was separated into two categories (PS 31 and PS 32) due to textural differences. Sample PS 31 contains fine sands of calcite and calcite-coated quartz, and low biodiversity but high abundances of Gyraulus parvus and Sphaerium transversum. Such findings suggest deposition from isolated bodies of concentrated water in the stream channel. Sample PS 32 possesses finer grain sizes and lacks fossil content, both of which are typical of deposition by wind. Therefore, current data and comparisons to modern stream deposits support the presence of microenvironments within the ancient stream channel, and signifies that sediment deposition and mollusc diversity are not completely controlled by stream flow.