Suspect Terranes in the North American Margins and Relative Sea-Levels

Sea-level trends deduced from tide gauges show considerable variation along strike both on the convergent (western) and divergent (eastern) edges of the North American plate. That portion of the variation unrelated to Quaternary glaciation and deglaciation may reflect the differential reaction to extension and sediment loading in the east, and in the west subduction and translation of terranes welded onto the North American craton. These autonomous blocks appear to impart distinct signatures on records of relative sea levels, suggesting promise in deducing complex terrane topography of other margins using tide-gauge data. Uncertainties in these deductions can be reduced only with expanded tide gauge coverage or by application of new geodetic techniques (Very Long Baseline Interferometry or differential Global Positioning System).