Quantifying the Cryptic Topography of the High Plains

Abstract

AbstractThe origin of the presently high topography of the High Plains of the western United States has been a topic of considerable debate. We remove the directly quantifiable effects of thrust loading and post‐Early Cretaceous sedimentation to identify topography supported by subsurface means. We term this amount of unexplained topography cryptic topography. To determine the amount of topography that can be attributed to sedimentation, thrust loading, and the flexural response of the lithosphere, we estimate the thickness and density of the sedimentary rocks that overly the Dakota Formation from well logs. We then calculate the flexure that results from the emplacement of these rocks as well as the thrust load of the Rocky Mountains. We then subtract these effects from the present day Dakota horizon. The results of removing these effects indicate that between ∼1 and 1.5 km of topography at the western edge of the High Plains is cryptic and demands some change in the deeper crust or mantle since the deposition of the Dakota Formation.