The next Accretionary Wedge call for submissions is up over at cryology and co. Here is the blurb:
What remains to be discovered for future earth scientists what we (still) don't know about earth? What are the geological riddles that still lack answer - all questions are allowed - it could be a local anomaly, or a global phenomena, or something strange...(Naturally you can also include a possible answer to your problem)
So what don't we know?