Were there oceanic plateau formation for before plate tectonics era? Perhaps later, plateau gave rise to terrenes along west coast of N. America. Might Mars serve as a model of what pre-tectonic era looked like on Earth? Are there plateau on Mars? If not, then this would seem consistent with such plateau formation for after commencement of plate tectonics. Plate tectonics might have started in middle or later Archean (1-2 Byrs after origin) for Earth.