Upland Chert Gravel in the Emporia, Kansas Vicinity: New Exposures, Observations, and Stratigraphic review

Abstract

Upland chert gravel deposits are common on high terraces, hilltops, and drainage divides across much of southeastern and east-central Kansas. Recent building and landscaping excavations have revealed chert gravel in several parts of northwestern Emporia on or near the divide between the Neosho and Cottonwood drainage basins. Assuming a late Pliocene age for highest chert gravel yields an average incision rate of ∼1.3 cm per 1000 years. Chert gravel is typically found on high terraces and drainage divides north of eastwest flowing stream valleys and west of north-south trending streams, which suggests regional crustal tilting downward to the south and east as a plausible mechanism to explain this widespread valley asymmetry. Much confusion surrounds the stratigraphy of upland chert gravel deposits on a regional basis. Improved age information and reconstruction of paleodrainage would be necessary to establish stratigraphic relationships of upland chert gravel deposits among the various drainage basins.