The Ohio Geological Society

Slippery Ice; Mapping the Fluctuations of the Last Glacial Maximum in Central Ohio

Tom Valachovics

Thursday, April 18th, 2024

Hilton Doubletree, 175 Hutchinson Ave, Columbus Ohio 43235

Talk Begins at 1 PM

(Optional Lunch ~11:30 AM-12:45 PM

El Acapulco 7475 Vantage Dr.
Columbus, OH 43235 )

The terminal position of the last glacial maximum (LGM) in central Ohio has been defined as the Cuba Moraine since Leverett recognized it as the termination of the Scioto Sublobe in 1902.  However, tracing this moraine onto the rugged terrain of Allegheny Escarpment and providing a timing for this termination proved difficult.  Since 1902, multiple technological advancements have furthered our understanding of the LGM.  Recent significant technological advancements help better visualize the topography through LiDAR and understanding the timing of glacial deposition with absolute age dating techniques such as radiocarbon and optically stimulated luminescence (OSL).  Rather than being the limit of a single advance, the LGM appears to be a palimpsest landscape of two significant ice advances in Central Ohio that were separated by a few thousand years of time.  The advancement of the ice sheet to the Cuba Moraine in Clinton County approximately 26,500 years ago and deposition of the associated Caesar Till is the classical LGM advance. A second advance to the Reesville Moraine in Fayette County reached the LGM near the Lattaville Moraine in Ross County approximately 22,000 years ago as evidenced by buried forest deposits. Multiple advances separated by almost 5,000 years to the same terminal position changes the historical view that glaciers advanced to their terminal position, and then retreated in a stepwise orderly fashion during deglaciation.

Tom Valachovics joined the Ohio Geological Survey in 2019 after previously working with the Indiana Geological and Water Survey. Tom holds a BS in Geology from Grand Valley State University and a MS in Geology from the University of Toledo. He has experience working in glaciated terrain in Ohio, Michigan, and Indiana. Tom specializes in Quaternary Geology and has worked in both the Survey’s groundwater group, where he helped produce the Groundwater Vulnerability Map of Ohio, and in the mapping group where he currently produces county scale glacial and surficial maps throughout the state. He has professional interests in the hydrogeology of glacial deposits and using geochronology techniques to help better understand the deglacial history of the State.