Geological Constraints on Quarry Development in the Central Appalachians
Linda E. Sohl
LDEO/Columbia University
Philip C. LaPorta
CUNY Graduate Center
 The chert quarries of the Wallkill River Valley of northwestern New Jersey occur in linear outcrop trends and are mined systematically over time within any ore-bearing horizon.  The Cambro-Ordovician cherts are polydeformed and often occur in an outcrop as steeply dipping stratabound layers of nodules, boudinage and infillings with paleokarst features.  Present at the quarries is evidence of formal task subdivision, indexed by the presence of sophisticated mining technology, fashioned largely from meta-sedimentary rocks of Lower Silurian age.  The concept of “Folk Geology” operative in the valley is proposed and supported by ethnographic studies.