The current evidence, patterns, and history of seafloor spreading in the northeast Pacific; the character and history of the San Andreas system of deformation; and some geologic implications of their relations to a worldwide tectonic scheme are reviewed.

The NE-trending East Pacific rise enters the Gulf of California from the Pacific Ocean. The essentially contemporaneous and parallel Gordo and Juan de Fuca ridges lie off the coasts of northern California and Oregon. According to the New Global Tectonics, the SE-trending San Andreas zone is a transform fault which connects these two segments of the World Rift system. Furthermore, according to the rigid-plate concept, the adjoining oceanic and continental blocks are moving northwest and southeast away from the oceanic ridges, and past each other along the San Andreas. On the other hand, according to the new comcepts, part of the sea-floor magnetic pattern and the northeast Pacific fracture zones (transform faults) indicate an earlier (10-30 m.y. ago) north-south oceanic ridge trend acc mpanied by east-west crustal extension. However, since the present crustal dynamics typified by the San Andreas system of deformation has been operative for a much longer time (at least 80 and possible for more than 135 m.y.), some doubt is cast on the interpretation of the San Andreas as a geologically young transform fault. These and other contrasting geophysical data and interpretations from the oceans tested against geologic data and interpretations from

End_Page 2209------------------------------

the continents serve to emphasize tectonic discrepancies. This approach, versus searching for data and interpretations which tend to confirm the New Global Tectonics, may best stimulate both continental-based geologists and ocean-based geophysicists to obtain critical information leading to the true world tectonics.

End_of_Article - Last_Page 2210------------