Ancient rock art is better known in western North America, but it is also an important feature in the historical landscape of eastern North America. This booklet reprints a report first published in 1934 by the Pennsylvania Historical Commission. Donald A. Cadzow, an archaeologist, surveyed the petroglyphs discovered on certain rocks in the lower Susquehanna River, between York County and Lancaster County. In addition, petroglyphs from other parts of the state are noted.