Can you give some examples? (I never lock down on a model to the exclusion of new evidence -- looking stupid isn't all that difficult for me, so I don't need to seek out new ways, such as suppressing new evidence... )webolife wrote:...and given what appears to be increasing evidence for mantle blocking...
BTW, on a related topic, did you ever see any of my musings on the Ceres Impact Hypothesis? The idea is that the continental granites, and the oceans, arrived during the Late Heavy Bombardment, courtesy of the break-up of Ceres by some sort of collision. Granites and water are the stuff of which asteroids in the vicinity of Ceres are made, and are not otherwise abundant in the inner solar system. The late arrival of granites on Earth is suggested by their uneven distribution. Pretty much everybody's model of the Earth has it as completely molten in its youth. As such, the stratification should have been near perfect, and the completely molten granites should have spread out over the entire globe, making one continuous layer, ~15 km deep, instead of clumps of granites covering 29% of the Earth's surface, with an average thickness of 40 km. Of course, the Earth could have been semi-molten, and a batch of high-viscosity granite could have bubbled up to the surface, and cooled too quickly to spread out over the entire globe. But I don't know of anybody who is saying that the young Earth was that cool. Furthermore, many scientists believe that the oceans were donations from asteroids, mainly because the Earth should have been hot enough to boil off all of the liquid water. So I'm saying that the granites and the water both arrived at the same time. The proposed impacter would have had a volume of 8.97 × 109 km3, with 85% granite and 15% water. C-type asteroids can contain up to 22% water, and 75% of all asteroids are this type, including Ceres, which could be as much as 50% water.