It's getting fashionable to hypothesize about meteor, asteroid or comet impacts. At http://phys.org/print267255104.html … a new study is claiming a cosmic body plunged into the southern ocean and generated a massive tsunami wave that plunged the world into the Ice Ages. See also http://joannenova.com.au/2012/09/massive-eltanin-meteor-2-5-million-year… which has lots of diagrams and maps. The paper on the subject will be in the forthcoming Journal of Quaternary Science – but I can already see problems that dissenters might pick up. They place the ocean impact at the boundary of the Pliocene/Pleistocene, perhaps for convenience but it was actually getting quite cold in the Pliocene (towards the end). What if the kind of geology re-write as advocated by Allen and Delair was in order, the Pliocene overlapping the Pleistocene (on the basis the Pleistocene is a late addition to geochronology and was designed to accommodate the Ice Ages).
Meanwhile, at http://phys.org/print267249193.html … the Popigoi Crater in the far north of Siberia, the result of an impact event dated 35 million years ago, is full of diamonds – lots and lots of diamonds.
George Howard has also updated at http://cosmictusk.com/unfiltered-unsorted-surovell-holiday-et-al-in-pnas…