CompuServe Messages

Doug >> I gather geologists are still arguing about subduction-pull versus spreading-push as the more important force moving the plates. If it is push from spreading, that is the irresistible force that cannot easily be "satisfied" by mere crumpling at the collision sites, which can only absorb a limited amount of crust. Something has to dive.<< Considering the push aspect.. If the force is push…. it would be much like a hydraulic type of effect… pressure building between two sides to push them apart…this to me seams impossible in that if the pressure was enough to transmit force along the hundreds sometimes thousands of miles of crust to the front and force subduction…. it would blow out at the rise spewing magma miles into the air…seeking the path of least resistance. The thin crust at the rise offers very little bearing for the force to be applied it would seek the the easy way out. Blowing away a few miles of crust in an area that is already fractured and leaking would be its natural route. >> Even if the force is "none of the above", the evidence for plate tectonic motions is strong enough to declare that it must exist, whatever it is. << I am not convinced that the evidence proves motion beyond adjustments in the plate interfaces. The conclusion that the motion continues in a direction ending up in subduction is a stretch. Kamron