A new exposure of glacial and glaciolacustrine sediments at Antes Fort allows for revision of the chronology of pre-Wisconsinan glaciation in central Pennsylvania. Lacustrine sediments from a proglacial lake in the West Branch Susquehanna River valley have reversed remanent polarity with a site mean paleomagnetic declination of 193.8° and inclination of -13.1°. The magnetization is probably a true detrital remanence from the time of deposition and is not significantly affected by postdepositional diagenesis. We propose that the Antes Fort till was deposited during either pre-Illinoian glaciation F or G of G. M. Richmond and D. S. Fullerton (1986, "Quaternary Science Reviews," Vol. 5, 183-196) between 770,000 and 970,000 yr ago. We suggest that it is equivalent to the Penny Hill till in the West Branch Susquehanna River valley and tentatively correlate it westward with the reversed polarity terrace deposits and Minford Silt in western Pennsylvania, West Virginia, and Ohio; the West Lebanon till in Indiana; and the A4 tills (or possible B tills) in Iowa and Nebraska.