Rhaedas

The erosion is from either wind or water. The patterns I've seen suggest water erosion, not sandblasting. By all means, if there's evidence to show otherwise, I'd love to see it.

I don't subscribe to any of the Planet X/"aliens built the pyramids" theories, but I do think the Sphinx is much older than the rest of the area. Confirmation of that leads to more questions, but I don't think anyone wants to rock the boat of modern egyptology's timelines.

contracycle

As I recall, the Planet X/Nibiru/Nemesis idea has been around for a couple of decades. It argues that there is a planetary sized body on a very long, very elliptical orbit which passes through the solar system every so often (like thousands of years) and causes lots of disruption to the normal cyuclism of the solar system, dislodging cometary shrapnel from the Oort cloud.

A link on hypothetical planets including both Planet X and Nemesis is here:
http://seds.lpl.arizona.edu/nineplan...o.html#planetx