CompuServe Messages

Hi, Kamron– >> A solid does not have convection. Hmph, you answer a complaint about dogmatism with another proof by dogmatic assertion. We know solids can flow (consider how copper wires are made), and have lab experiments showing solid rock can do it under pressure. We have good reason to think Earth's core is hot. Convection in the mantle is a reasonable assumption given these facts, and it cannot be wished away without evidence. Have you visited the mantle lately? That is about the only way to prove it does _not_ convect. >> The force it [convection] would exert on the plate would be in the opposite direction than is required to move the plate because the plates generally slant upward towards the rise. Ah, the angling plate had me thinking subduction zone. Newton's ghost will get you for this; if the rising material is driven sideways toward the rise, conservation of momentum says the plate is thereby driven away from the rise. >> Taking the Mid Atlantic Ridge as an example and looking at the section between the latitudes of Florida and the eastern most tip of S. America the distance covered would show that the plate has shifted nearly two thousand miles more than its counterpart or it has nearly double the speed. That is clearly impossible since the plate is a single mass how can it travel at different speeds? I have always assumed that while the plates are constant in shape to a first approximation, they do some intra-plate adjusting when looked at more closely. My mental picture is of a glacier – it is best regarded as a solid mass whose shape is not easily changed, yet it manages to flow around bends and such tricks. I have a vague notion that fracture zones are examples of such adjustments. The spreading between S. America and Africa began, I believe, at the southern end. While the crack was spreading north, the southern areas were already moving apart, with new seafloor being created between them. Transform faults allowed the spreading to continue until the crack extended northward and spreading rates become matched – the plate shape changed as it was first added to in the south only. The southern Atlantic did not open faster so much as it opened earlier. >> You still have not solved the problem of the shift faults extending into the opposite side of the Rise matching the pulled side I thought I just did. Maybe I will try again when time permits. >> There is also very little gravel below this [K-T] boundary aside from faults that were back filled. Hows that for weird? So what were those conglomerate _layers_ I hiked through in the Grand Canyon too long ago to admit? Looked like an awful lot of gravel to me. There are occasional irregularities near the K-T boundary, but in your theory I would very much expect to find huge piles of gravel and pre-Cretaceous erratics _between_ Cretaceous and Tertiary layers at almost every point, not just India (besides, the Deccan Traps were more or less finished before the K-T and are less remarkable than the older Siberian Traps and the Ontong-Java plateau). As wide as 30 centimeters? You have whole continents (and all the gravel in the world) flying through the air and never more than 30 centimeters of deposits that show no evidence of pre-Cretaceous origin?!? –Doug