Geologist Robert Schoch's water-erosion analysis shows the Great Sphinx is really 7,000 to 12,000 years old, thousands of years older than mainstream Egyptology allows

Geologist Robert Schoch, of Boston University, argued starting in 1991 that the vertical, undulating weathering patterns on the walls enclosing the Great Sphinx look like the product of sustained rainfall rather than the wind-and-sand abrasion typical of Egypt's historical climate. Since Egypt hasn't seen rainfall on that scale since roughly 7000-5000 BC, Schoch concluded the Sphinx's core body must have been carved that far back, thousands of years before the conventional attribution to the pharaoh Khafre around 2500 BC.

The mainstream rebuttal, developed by geologist James Harrell (University of Toledo), Egyptologist Colin Reader, and Sphinx excavation director Mark Lehner, argues the same weathering pattern is fully explained by softer limestone layers eroding faster than harder ones under ordinary wind and occasional flash-flood runoff, compounded by the fact that the Sphinx spent most of its history buried in sand, which limits how much erosion time it actually accumulated. They also dispute Schoch's subsurface seismic readings as reflecting natural variation in the bedrock rather than a deeper weathering profile, and point to comparable weathering on securely dated Old Kingdom tombs cut from the same limestone. Michael Heiser reviewed this Reader-versus-Schoch exchange on his own site and came down on the side that a dramatically older Sphinx isn't required once burial history and limestone bedding are accounted for.

On how this intersects young-earth chronology and the post-Flood repopulation timeline specifically, the honest finding is that substantive engagement is thin. Searching the major young-earth organizations (Answers in Genesis, the Institute for Creation Research, Creation Ministries International) turns up no dedicated article taking on Schoch's redating claim directly; this is a case where the expected debate mostly isn't there in citable form. The one identifiable named source is narrower: the Northwest Creation Network's "Biblical Chronology" article (nwcreation.net, also mirrored on CreationWiki) proposes that a post-Flood ice age, within an Ussher-style young-earth timeline, overlapped early Egyptian history and ended roughly a century after Joseph, and suggests in passing that this wetter climate window "explains…the water erosion on The Great Sphinx," using it as circumstantial support for a compressed Egyptian chronology rather than adopting Schoch's actual multi-thousand-year redate, which would in fact be too old even for a young-earth Flood date typically placed around 2500-2350 BC. Beyond that one specific mention, there isn't a developed young-earth literature wrestling with Schoch's claim on its own terms: worth stating plainly rather than manufacturing a bigger fight than actually exists in print.