Mesoscopic to macroscopic block-in-matrix structures are widely distributed in the Blue Ridge belt of the southern Appalachian orogen. The belt is subdivided into four tectonostratigraphic terranes: (1) the eastern Upper Proterozoic Toe terrane, consisting of metasedimentary rocks, metabasites (amphibolites), and ultramafic rocks; (2) a western, Middle Proterozoic, cratonic terrane, the Sherwood terrane, consisting of metamorphosed granitoid rocks and structurally overlying Upper Proterozoic to Paleozoic metasedimentary and sedimentary rocks; (3) the enigmatic, intervening Cullowhee terrane, lithologically similar to the Toe terrane, largely of unknown age but yielding a Middle Proterozoic age from one area in the north; and (4) a Middle...