- 11,700 years ago, the Wisconsinian glacier receded from North America, ending the Pleistocene epoch and leaving behind glacial deposits. - The researcher examined gravel pits in Crawford County, PA to observe bedding and measure the strike and dip of clasts to determine the paleoflow direction of ancient glacial rivers. - At 5 of the 35 gravel pits studied, clast imbrications indicated consistent southward paleoflow, suggesting present drainage patterns are inherited from Pleistocene systems. However, too few sites showed visible imbrications to construct an accurate paleoflow map.