I have recently become aware of Robert M. Schoch's water erosion hypothesis, where he proposes that the Great Sphinx of Giza (or at least the oldest parts of it) are likely much older than taught in traditional Egyptology. While currently dated to the reign of Khafra (26th century B.C.), Schoch suggests that it is more likely at least from around 5000 B.C., and maybe even as far back as 7000 to 9000 B.C..
From what I've understood, this has been rejected by mainstream Egyptology, but I have not been able to understand why. The counter-arguments against the Water Erosion itself do not seem all that sound, and arguments pointing out that there were no known civilization going so far back - at least not that could have performed such an extraordinary feat of construction - fall flat when sites such as Göbekli Tepe and Gunung Padang have been discovered.
So, what I would like to know is how the Sphinx was dated to the reign of Khafra in the first place, and how (if at all) Egyptology have firmly rejected evidence suggesting that it might be older than assumed.
PS: I've submitted a similar question over at askscience.
The Sphinx Temple was built with stones cut out from the Sphinx colosseum, so they are the same age.
The Sphinx Temple was built after the Khafre Valley Temple because it was built upon the foundation of the north enclosure wall of the Khafre Temple and even incorporates one of its stones.
Also, the Sphinx enclosure respects the causeway of Khafre, a drainage channel of the causeway leads into the Sphinx enclosure and no potery earlier than from the 4th dynasty was found near the Sphinx.
The water erosion hypothesis doesn't hold up because other mastabas and pyramids at Giza show the same degree of erosion (Khentkaus for example) which is mainly caused by carbonic acid (indirectly by rain).
Edit:
traditional Egyptology
mainstream Egyptology
All Egyptology must be evidence based, calling something mainstream or traditional doesn't make it any more or less true.
