Yampa River-Colorado River Drainage Divide Origin Determined from Topographic Map Evidence, Southern Routt County, Colorado, USA

Detailed topographic map evidence and a new Cenozoic geologic and glacial history paradigm are used to determine the previously unexplained Yampa River-Colorado River drainage divide origin. The Yampa River now flows in a north direction away from the Colorado River (between the Park Range to the east and the Flat Tops region to the west) before turning in a west direction to reach the Unita Mountains where it joins the south-oriented Green River, which eventually joins the southwest-oriented Colorado River. Topographic maps show the Yampa-Colorado River drainage divide is asymmetric with steeper slopes leading to the Colorado River, barbed (south-oriented) tributaries leading to north-oriented Yampa River headwaters (especially near the Yampa River turn to the west), and evidence of a large north-to-south oriented diverging and converging channel complex that preceded present-day drainage routes. Map evidence is interpreted to mean massive south-oriented floods flowed through what are now north-oriented Yampa River headwaters valleys and that headward erosion of a deep west-oriented valley beheaded and reversed those south-oriented flood flow channels to create the north-oriented Yampa River headwaters and the Egeria Park area Yampa-Colorado River drainage divide seen today. Large south-oriented floods leading to the Colorado River (while regional uplift was occurring) are inconsistent with accepted Cenozoic geologic and glacial history paradigm predictions, but are predicted by a newly proposed Cenozoic geologic and glacial history paradigm in which a thick continental ice sheet created a deep “hole” by eroding underlying bedrock and also by causing crustal warping that raised the present-day northern Colorado east-west continental divide as immense south-oriented meltwater floods flowed across it.