PA Department of Conservation & Natural ResourcesStatewide distribution of bedrock geologic units mapped at 1:250,000 scale, compiled by C. E. Miles and T. G. Whitfield, Pennsylvania Geological Survey (PGS), and published by PGS in 2001. Data were modified from source maps used to compile PGS Map 1, Geologic Map of Pennsylvania. NOTE: to exact match the symbology of bedrock geology in the PaGEODE application, adjust the transparency to 50%.ArcGIS DynamicMapLayerhttps://hub.arcgis.com/datasets/662dbfd818214a528f0ef3a11556da9c_13engPennsylvania Department of Conservation and Natural Resources Open Data PortalPublicSilurian [Pennsylvania]Web servicesPennsylvaniaLast Modified: 2026-04-14