Subdivisions and Correlations of Upper Devonian Greenland Gap Group and Lockhaven Formation of Central Pennsylvania
The Scherr and Foreknobs Formations of the Greenland Gap Group (south-central), and the Lockhaven formation (north-central) near the Allegheny Front of Pennsylvania contain several distinctive and widespread lithologic units. The Minnehaha Springs siltstone is recognized in both the lower Scherr and lower Lockhaven formations and is considered to be isochronous throughout the study area. Chronostratigraphic equivalents to the Pound Sandstone Member of the Foreknobs Formation are recognized in the upper Lockhaven formation. These lithologic and chronostratigraphic subdivisions of the Chemung strata of central Pennsylvania facilitate correlations with West Virginia, Maryland, and New York.
Development of the chronostratigraphy of the Chemung interval along the Allegheny Front of Pennsylvania permits the construction of less ambiguous sedimentologic and paleoshoreline models for these strata. Future chronostratigraphic correlations with the Chemung interval in outcrops of eastern and northern Pennsylvania and in the subsurface of western Pennsylvania will result in a clearer, dynamic model of the interplay between the Acadian orogeny, the resultant Catskill delta, and the Appalachian sea.
AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.