STRUCTURE OF THE GLENARM SERIES IN CHESTER COUNTY, PENNSYLVANIA
The Woodville structure is a hook-shaped belt of Baltimore Gneiss surrounded by Glenarm rocks. The hypothesis that the structure is a nappe, rather than an upwarp involving two gneiss-cored anticlines, is based primarily on the orientation of B lineation in the Glenarm rocks, taken in conjunction with the map pattern; the southwestward plunge of the Glenarm rocks under the gneiss along the northeastern side of the hook indicates that this segment of the border of the gneiss is the inverted limb of a recumbent fold.