Heh... that link looks mighty familiar for some reason. ;')
I just took a look at Dr Schoch's new site:
http://www.robertschoch.net/
Schoch's links on the homepage are screwed up. Here's an example of a correct link:
http://www.robertschoch.net/articles.html
Geological Evidence of the Sphinx
Dr. Robert M. Schoch
http://www.robertschoch.net/articles/geological_evidence_sphinx.html
"Based on my field observations of the granite ashlars and the underlying limestone blocks, I believe that the limestone core blocks of both the Sphinx Temple and the Valley Temple were exposed to the elements and underwent considerable weathering and erosion before the granite was put into place. In places the backs of the granite facing blocks were cut in an irregular, undulating pattern so that they would complement or match the irregular weathering pattern on the limestone blocks that they were used to refurbish... The general Egyptological community agrees that the granite facing on the Sphinx and Valley Temples is attributable to Khafre... On site I found an inscription carved into the granite of the Valley Temple which according to West... appears, on stylistic grounds, to be an Old Kingdom inscription. It seems a good assumption that the limestone core blocks would have been freshly cut (that is, unweathered) when initially used to construct the temples. Therefore if the granite facing is covering deeply weathered limestone, the original limestone structures must predate by a considerable degree the granite facing. Obviously, if the limestone cores (originating from the Sphinx ditch) of the temples predate the granite ashlars (granite facings), and the granite ashlars are attributable to Khafre of the Fourth Dynasty, then the Great Sphinx was built prior to the reign of Khafre... As mentioned above, the ashlars bear Old Kingdom inscriptions and therefore must be at least as old as the Old Kingdom. But the Old Kingdom inscriptions could conceivably have been carved into still earlier structures."
[in the video, Schoch shows the spot where the inscription occurs, and the translation he gives is, "beloved of, living forever", IOW, two fragments of a longer original, i.e., the granite was quarried from an existing monument and laid over the eroded limestone original; this is actually a weak part of the theory, as the erosion could have occurred prior to the quarrying of the limestone, which was then assembled into the two temples; in that case, the granite could have been obtained from another abandoned structure during, say, the New Kingdom, when the Giza monuments experienced a bit of a renaissance. IMHO, I agree with Schoch et al that the head was recarved; my view is that it was done during the Ethiopian Dynasty / 25th Dynasty]