Since the concept of sea-floor spreading was first introduced by Dietz (1961) and Hess (1962) a voluminous literature has developed to support Mesozoic continental drift. Notable advances in paleomagnetism, polar wandering, and sea-floor spreading (Runcorn 1962, Vine & Matthews 1 963, Vine 1 966) were followed by formulation of the theory of plate tectonics (McKenzie & Parker 1 967, Le Pichon 1 968, Morgan 1 968, Isacks et al 1 968, McKenzie 1 972). Emergence of the plate or new global tectonic theory has provided a unifying worldwide explanation for processes (Dewey & Bird 1 970). New models for mountain building involve plate motions at divergent and convergent plate boundaries. Relegated to virtual obsolescence (Dickinson 1971) are the classical geosynclinal concepts widely held until the mid-1960s. The concept of plate tectonics compelled geologists to reexamine sedimentation, igneous activity, deformation, and metamorphism on both regional and global scales. Initially, attention was devoted to plate theory as it affected contemporary geosynclines, island arcs, mountain ranges, and oceanic domains (Mitchell & Reading 1 969, Bird & Dewey 1970, Dewey & Bird 1970, Coleman 1971, Dickinson 1971, Gilluly 197 1 , Oxburgh & Turcotte 1971), but the success of these efforts led to the application of the plate model to Paleozoic and late Precambrian orogenic terranes such as the Uralides and Appalachian/Caledonian Orogen (Hamilton 1 970, Bird & Dewey 1 970, McElhinny & Briden 1 97 1 ). A sequel has been a growing tendency to apply the theory to the Precambrian record and to evaluate the possible role of the plate mechanisms during early continental evolution (Dewey & Horsfield 1 970). Some believe that ancient mobile belts, and even the Archean greenstone belts, represent the impact scars of protocontinental fragments colliding with each other, with island arcs, or with oceanic crust (Gibb 1971, Gibb & Walcott 1971, White et al 1971, Condie 1972, Talbot 1973). How justified is application of the plate hypothesis to earlier geologic time? Before making judgment it may be advisable to examine critically the