INVESTIGATIONS INTO LANDSCAPE EVOLUTION THROUGH THE EDMAP PROGRAM

Through participation in the U.S. Geological Survey's EDMAP program, significant strides were made in understanding the landscape evolution of the Black Hills of South Dakota and Wyoming. The surficial geology of the Chicken Creek Quadrangle, SD and the Spearfish Quadrangle, SD was mapped in the summers of 1999 and 2000. The dominant mapped unit was unconsolidated Quaternary fluvial sand and gravel genetically related to both the modern rivers and ancestral rivers draining the Black Hills. These maps serve as a foundation for understanding the distribution and thickness of sand and gravel deposits in the context of ground water recharge, ground water resources, and aggragate resources. Furthermore, the mapped fluvial deposits reveal a suite of terraces resulting from Quaternary fluvial incision and erosional exhumation of the Black Hills. The Black Hills are being exhumed from the High Plains as broad knickzones, initiated far downstream on the Missouri River, work their way headward. The shape and gradient of the knickzones is largely determined by rock type; the distance they have propagated upstream is highly correlated to drainage basin area. These data contributed to completion of a Ph.D. dissertation and led to the publication of two journal articles. Continued research based on these data is ongoing with more publications envisioned for the near future.