DRAINAGE REORGANIZATION DRIVEN BY PROGLACIAL LAKE SPILLOVER ALONG THE WISCONSINAN AND ILLINOIAN ICE MARGINS OF CENTRAL AND SOUTHEASTERN OHIO

Throughout the Pleistocene, advancing ice sheets dammed rivers and impounded proglacial lakes across the Appalachian Plateau of central and southeastern Ohio. Many of these proglacial lakes overtopped drainage divides ultimately leading to drainage reorganization at both local and regional scales. Some spillover events forced localized incision across breached drainage divides preserved today by narrow gorges, knickzones, and clear patterns of drainage reversal and capture. This study focuses on an episode of incision along the Illinoian ice margin near the present-day Hocking Hills of southeastern Ohio.

Using a combination of field mapping, surveying, and digital terrain analyses, this work investigates how a spillover and drainage integration event lowered baselevel for Pine and Queer Creeks and a wave of incision propagated upstream from the spillover point. These drainage systems incised through the gently dipping Mississippian strata that underlie the Hocking Hills with prominent knickpoints forming on the resistant Blackhand Sandstone Member of the Cuyahoga Formation. The modern-day elevation of waterfalls is largely a function of the local thickness and dip of the Blackhand Sandstone within the Hocking Hills, but the dynamics of how far upstream waterfalls propagated and, in some cases, how waterfalls are still moving upstream are more puzzling problems. This ongoing case study in the Hocking Hills informs a broader look at similar spillover-incision events along the Illinoian and Wisconsinan ice margins in Ohio.