Maps and Rig Count
The Devonian Marcellus Formation (or Marcellus Shale) is the major sedimentary bedrock unit under the Allegheny Plateau Region of North America. It gets it's name from the original outcropping found near Marcellus, New York during a geological survey in 1839.
from the Penn State Marcellus Center for Outreach and Research
an interactive rig count map from Baker Hughes
