REVERSED-POLARITY GLACIAL SEDIMENTS AND REVISED GLACIAL CHRONOLOGY, WEST BRANCH SUSQUEHANNA RIVER VALLEY, CENTRAL PENNSYLVANIA

A new exposure of glacial and glaciolacustrine sediments at Antes Fort allows for revision of the chronology of pre-Wisconsinan glaciation i n central Pennsylvania. Lacustrine sediments from a proglacial lake in the West Branch Susquehanna River valley have reversed remanent polar ity with a site mean paleomagnetic declination of 193.8-degrees and in clination of -13.1-degrees. The magnetization is probably a true detri tal remanence from the time of deposition and is not significantly aff ected by postdepositional diagenesis. We propose that the Antes Fort t ill 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, We st Virginia, and Ohio; the West Lebanon till in Indiana; and the A4 ti lls (or possible B tills) in Iowa and Nebraska. (C) 1994 University of Washington.