Part One: Ancient Catastrophes, Flying Machines and Cold Fusion

Interesting post, George. Looking forward to seeing how you weave all this stuff together. Meanwhile, from Space.com, orbiters around Mars have discovered what they believe to be massive glaciers under the windblown soil. They were deduced by the shape of craters into them which show terraced sides. May have some relevance to what happened with the physical impact on the ice sheet during the YD impact(s). Cheers - http://www.space.com/30502-mars-giant-ice-sheet-discovery-mro.html

I E LAPTOP KEYBOARDS!!!!! ce again a laptop keyboard has completely erased my entire comment, and almost all the time when I am just finishing it. GRRRRRRRRR ...start again.... dang it Agimarc, surprise surprise, Steve disagrees with a stupid interpretation. A) This is not the only possible interpretation for those terraces; B) The authors did not show that they even considered other explanations; C) They did not show why other eplxanations might be possible or should be rejected; D) If ice was the LOWER layer, then ice would have been the weaker layer, and thus the lower layer would have been the layer with more impact radius; E) I disagree with their jumping to this particular explanation/speculation. The craters would be the way they are shown in the images if the crater had wall angles just slightly lower than the "angle of repose" of the target material. Such a condition would make it ripe for avalanches. I propose that a nearby later impact could have shaken the crater walls enough to cause avalanches - all the way around the crater. Partial avalanches happen on Earth a lot, where the material slides part way down and then stops, due to the inability of the gravity to overcome the friction anymore. I think that these all being in one region indicates that the later impact was IN that region, affecting similar craters (perhaps from a common impact shower) the same way. I tentatively interpret the one high point on the terrace as an antipodal effect - which may possibly be used to point at the location of the later impact. Triangulating might be VERY interesting.