Geology, Gravity, and Magnetics at Juncture of Southern and Central Appalachians, New Castle Area, Craig County, Virginia

ABSTRACT A combined geologic-geophysical survey was carried out in the New Castle area, Craig County, Virginia, in the Valley and Ridge province at the junction of the central and southern Appalachians. In the map area the major structures, the northeast-trending Johns Creek syncline and Sinking Creek anticline, are the northernmost features of the southern Appalachians. Geophysical data indicate a southeastward migration of the axes of these two structures with depth. The Saltville fault, which breaches the nose of the Sinking Creek anticline at the surface, is not defined in the subsurface by geophysical data. The latter, especially those derived from magnetics, indicate that a north-northwest trend is present in the basement complex. Such a trend is almost at a right angle to the surface features in the area. This difference in direction of structural grain may reflect a Precambrian trend in the subsurface, or may be related to the change in trend between the surface structures of the central Appalachians on the north and those of the southern Appalachians on the south. Four smaller anticlines, the southernmost features of the central Appalachians in the area, show no definite pattern in the subsurface geophysical data and may be surface wrinkles in a larger encompassing synclinal structure.