PRESERVATION OF KEY GEOLOGIC SITES IN LANCASTER AND YORK COUNTIES, PENNSYLVANIA

Southeastern Pennsylvania contains complex geologic terranes with sedimentary, igneous and metamorphic rocks ranging from Proterozoic to Jurassic in age. Both the Lancaster County Parks and York County Parks have acquired land containing geologically significant sites.

As a site regionally renowned for structural exposure, Chickies Rock County Park, located along the Susquehanna River in western Lancaster County, is unsurpassed. This county park is also the type locality for both the Chickies Formation and the trace fossil Scolithus linearis and encompasses numerous ruins of a 19th century iron industry. Also in Lancaster County, Money Rocks County Park boasts the same ridge-forming Chickies Formation; its juxtaposition with a clay mine dating back to the 1880’s contributes to its notoriety. In addition, quartzites of the Chickies Formation at Money Rocks exhibit splendid tafoni weathering.

The basal member of the Chickies Formation, the Hellam Conglomerate, is well exposed at York County’s Rocky Ridge Park. This is the largest exposure of the Hellam Conglomerate, which is regarded as the oldest sedimentary rock unit in the region. The York Iron Company Mine, active between 1854 and 1888 is now preserved as York County P. Joseph Raab Park. The historic value of this mine, which contains open mine adits, building foundations, railroad tracks and mining tools, is outstanding.