Bedford County, Pennsylvania is situated along the western border of the Ridge and Valley physiographic province, which is characterized by folded and faulted sedimentary rocks of early to middle Paleozoic age.
(PA Geological Survey Map 13) The stratigraphic record of sedimentary rocks within the county spans from the Cambrian Warrior Formation to the Pennsylvanian Conemaugh Group (in the Broad Top area).
Chestnut Ridge is a broad anticline held up by the Devonian Ridgeley Member of the Old Port Formation, also made of sandstone and conglomerate.
The many boulder fields obvious as rocky and often treeless areas on mountainsides within the county formed as a result of seasonal freeze-thaw cycles during the Pleistocene.
Natural gas fields and storage areas exist in southeastern Bedford County, primarily within folded Devonian rocks south of Breezewood.