Pennsylvania Geological Survey
3240 Schoolhouse Road
Middletown, PA 17057


Gale C Blackmer
Acting Bureau Director and State Geologist
(717) 702-2052

Technical Contacts

Gary M. Fleeger
Geologist Supervisor
Specialty: glacial geology
(717) 702-2045


Rachel O'Brien
Associate Professor
Specialties: groundwater and surficial geology
Allegheny College
Meadville, PA 16335
(814) 332-2875

Eric Straffin
Associate Professor
Specialties: fluvial and soil geomorphology, Quaternary geology, sedimentology, stratigraphy
Edinboro University of Pennsylvania
Edinboro, PA 16444
(814) 732-1574

Duane Braun
Professor Emeritus
Specialty: surficial geology
Bloomsburg University of Pennsylvania
Bloomsburg, PA 17815
(570) 389-4587


Mapping Advisory Committee

The Pennsylvania Geologic Mapping Advisory Committee (GMAC) includes 27 members representing local, state, and federal agencies, private industry, and academia. Dr. Todd Bacastow of Pennsylvania State University is the chair. It meets twice a year to provide guidance on priorities for geologic mapping. The GMAC made use of an automated system for prioritizing quadrangles to be mapped as well as investigating current events and historical trends for their decision making.

Link to Pennsylvania Geological Survey 7.5-Minute Quadrangle Maps

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