There is a fringe theory that the Sphinx shows significant water damage as from a Great flood. This theory, I believe, suggests that the Sphinx in 12,000 years old. Which most people would find doubtful. I have no idea if the Great Pyramid shows water damage.
The Great Pyramid mainly shows damage from later builders who stripped the facing stones for reuse.
Another thing that I heard is that area was a lot greener thousands if years ago.
The water erosion of the Sphinx is just a fact; the geologist Robert Schoch suggested a more conservative 7000 year figure based on the length of time exposure to rain would cause the damage (iow, not a worldwide flood, which wouldn't cause the damage anyway), given that rainfall is no longer that much of a problem at Giza, for some reason. :^)
The Nile floods all the time...has for eons. They counted on it as it replenishes the soil for their crops.
The water damage is from rain running down the face of the stone. The area was a rain forest 12,000 years ago.
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Most floodwater motion is lateral. It gradually covers a normally water-free area -- and, then it gradually drains off. It seldom leaves erosion marks, other than deepening already-extant drainage channels (gullies, arroyos, etc.)
The sphinx (and the isolating cavity around it) are carved in striated, layered rock.
Wind/sand erosion in striated rock is lateral -- it enhances the striated appearance by selectively removing exposed parts of the softer layers.
OTOH, Rain erosion is vertical -- it cuts vertical grooves down vertical rock faces -- which cut right across both the harder and softer rock layers.
The horizontal grooves are Æolian (wind-driven sand) erosion of softer layers.
The vertical grooves are Pluvial (rain drainage) erosion.
The vertical erosion in the image is unquestionably Pluvial.
The cavity isolating the sphinx was carved as part of Sphinx construction.
The geological evidence is unequivocal.
TXnMA