Geology of the Blacksburg area, Montgomery County, Virginia

This 17 square mile area, on the western plunge of the Catawba syncline and the eastern plunge of the Price Mountain anticline, consists of the Cambrian Rome and Elbrook Formations thrust over younger Cambrian, Ordovician, and Mississippian rocks. The more or less age autochthonous rocks are the Cambrian dolomites of uncertain and Copper Ridge Formation, the Ordovician Chepultepec, Longview, and Mascot-Kingsport Formations, the Middle Ordovician limestones, and the Liberty Hall Formation; and the Mississippian Price and Stroubles Formations.

All fault structures within the area have formed during post-late Mississippian time. The apparent sequence of faulting is: (1) the westward thrusting of the Catawba syncline over the Price Mountain anticline; (2) the emplacement of the Pulaski thrust sheet; and (3) reverse movement along the eastward dipping Yellow Sulphur fault, which raised the Catawba syncline about 3000 feet relative to the Price Mountain anticline. Subsequent erosion has exposed Mississippian rocks in Price Mountain window of the Pulaski thrust and Cambrian rocks through the Blacksburg window of the Pulaski thrust sheet. Erosion has also revealed that near the base of the Pulaski thrust sheet are brecciated with the Elbrook, being typically a crush conglomerate, and the Rome being a phyllite breccia.