The folded belt of the Appalachians southwest of New York may be divided into two parts, a belt of unmetamorphosed rocks of the Appalachian Valley and a belt of more or less metamorphosed rocks lying between the southeast side of that valley and the border of the Coastal Plain. The metamorphosed belt consists of two parts, the Highland-Blue Ridge anticlinorium, which is a part of the Appalachian Mountains, and an area of overthrust rocks, the Martic thrust-block, which lies southeast of the anticlinorium and was brought to its present position by thrust-faulting.
The rocks of the metamorphosed belt are closely folded, and are broken by thrust-faults that show all gradations from broken, recumbent anticlines to clean-cut thrusts developed from them. The Martic overthrust is a low-angled thrust of the Scottish Highland type, which has carried the southeastern part of the Appalachians over the Paleozoic limestones . . .