Late Devonian Palaeogeography in southeastern New York and northeastern Pennsylvania

Abstract Four environmental zones evolved during the Late Devonian in southeastern New York and northeastern Pennsylvania. Definition of these zones is based on comparison of the Late Devonian rocks with modern sediments. The zones are: 1) upland alluvial plain, 2) lowiand alluvial plain, 3) littoral-paludal, and 4) marine. Generally, they were distributed from east to west, in the order given. A marine zone developed over most of the region during deposition of the Tully Limestone and its equivalents (earliest Late Devonian). A littoral-paludal zone and a lowland alluvial plain zone existed in southeastern New York at the same time. The shoreline shifted toward the West and northwest in a general pattern of marine regression at the end of this time. Terrestrial environmental zones developed across southeastern New York and northeastern Pennsylvania during deposition of the Oneonta Formation and its equivalents, the Walton Group and its equivalents, and the upper part of the West Falls Group. Upland alluvial gravels spread westward over successively broader areas in each of these intervals. The shoreline, however, maintained its position during deposition of most of these sediments. A marine zone occupied most of northcentral Pennsylvania throughout the Late Devonian.