We propose that the large lava flows on the Earth and Mars result from disruption of the crust by convergence of shock waves from a huge meteorite impact on the opposite side of the planet (the antipode). The presence of so many lava flows opposite meteorite impact craters on both planets is impossible to explain by coincidence. You may see it discussed in detail in http://charles_w.tripod.com/antipode.html and http://charles_w.tripod.com/dweber/mars_volcanos/mars_volcanos2.html.
It is proposed that the ocean trenches were formed by thermal shock upon previously warm ocean floor by cold water from polar regions moving down over the Pacific Ocean floor probably during the Cretaceous. Cold water descending into a wide crack further extended the crack to great depth. This huge amount of water in the crust makes the crust much lighter, so that hot plastic rocks from the mantle tend to move up toward this lighter zone and thus account for the volcanism that appears on the landward side of many trenches. This motion is currently ascribed to subduction, but if the explanation of mine is correct, it is not subduction, but a rise of plastic rock. This would also account for the bathaliths that appear there as well, almost impossible to explain given a diving, cold plate. The absents of a trench off of North America as well as opposite most of the other ridges other than the western side of the Atlantic Ridge are also impossible to explain from a diving plate. You may see this concept developed in detail in http://charles_w.tripod.com/trenches.html.
