12/21/11 11:15 AM White River-Keya Paha River drainage divide area landform origins, Sou…USA – Missouri River drainage basin landform origins research project Page 1 of 15 http://geomorphologyresearch.com/2011/12/21/white-river-keya-paha-river-drainage-divide-area-landform-origins-south-dakota-usa/ White River-Keya Paha River drainage divide area landform origins, South Dakota, USA December 21, 2011 · Niobrara River , South Dakota, White River A geomorphic history based on topographic map evidence Abstract: The White River-Keya Paha River drainage divide area discussed here is located in southern South Dakota, USA. Although detailed topographic maps of the White River-Keya Paha River drainage divide area have been available for more than fifty years detailed map evidence has not previously been used to interpret the region’s geomorphic history. The interpretation provided here is based entirely on topographic map evidence. The White River-Keya Paha River drainage divide area, which includes a Pine Ridge Escarpment region, is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood erosion of the White River-Keya Paha River drainage divide area ended when headward erosion of a deep and immense east-oriented White River valley captured the southeast-oriented flood flow. Preface: The following interpretation of detailed topographic map evidence is provided as evidence in the Missouri River drainage basin landform origins research project, which is compiling similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with and within certain adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored geomorphology paradigm, which is briefly described in the introduction below. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located. Introduction: The purpose of this essay is to use topographic map interpretation methods to explore South Dakota White River-Keya Paha River drainage divide area landform origins. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here. Authors Eric Clausen