 This observation was first made for contemporary stresses (the maximum horizontal principal compressive stress – sigma-hx); and also appears to hold for paleostress indicators between approximately 100 and 20 Ma (Pilger, 2003).This observation implies that the sublithospheric mantle over which the plates are moving comprises the same reference frame in which the hotspots are embedded.The mesoplate heuristic is very much a hypothetical construct.