<HTML>Hi again Claire,
I know you addressed this question to Garrett, but I've been debating this issue for awhile now and have a couple of sources to suggest.
First you should look at the two principle alternative hypotheses that were written shortly after Schoch's suggestion hit the popular press.
Harrell, J.A., "The Sphinx Controversy - Another Look at the Geological Evidence," KMT Vol 5 No. 2 (1994) p70-74.
Gauri, K.L., J.J. Sinai and J.K. Bandyopadhyay, "Geological Weathering and its Implications on the Age of the Sphinx," Geoarchaeology Vol. 10, No. 2 (1995) p119-133.
These folks are all geologists and very convincingly dismantle Schoch's "only running water can do this" assumption (I won't glorify it with the name hypothesis). Gauri et al. is particularly telling as it presents the case for salt crystal stress induced exfoliation (SCrySIE) accounting for the condition of the Sphinx enclosure. This suggestion is intellectually satisfying in its simplicity (nothing for Occam to slice off). They do a great job of establishing the weathering conditions at Giza and then apply them to the exposures in question. (By the way, the effects of SCrySIE were in the news again recently - the same process is "dissolving" the monuments at Luxor.)
If these don't convince you then you can even resort to looking at my article on this website.
However, I would guess that any geologist worth their salt, after reviewing Schoch's original paper and the two I've suggested, would come down on the side of Gauri and Harrell. Robert just hasn't made his case to either the geologists or the archaeologists.</HTML>