<HTML>The short answer is 'not too frequently', but I know a man who does! I have my spies, to whom I'm ever grateful.
Duncan,
In answer to your question - you're right to be confused - this matter is far from clear. There are many opinions but little proof.
Lehner has undertaken a study of the masonry used to restore the Sphinx. Two types of restorative masonry have been identified, the oldest of which consists of large limestone blocks, up to 1m in length, which have been placed directly against the in-situ strata from which the Sphinx was carved. These larger blocks are overlain by a second layer of later, brick-sized limestone masonry.
Lehner initially considered that the earliest masonry was placed as part of the original (Fourth Dynasty) construction and was intended to make good any natural discontinuities in the limestone. To demonstrate this, in the 1979/80 ARCE Sphinx Project he sought evidence for tool marks on the in-situ limestone underlying the large masonry. However, as Lehner states “...the profile of the core seems in all cases to be one of severe erosion, leaving the softer yellowish bands and harder intermediate strata showing a profile of successive rolls and undulations. These considerations would seem to indicate that the core-body of the Sphinx was already severely eroded when the earliest level of large-block masonry was added to it”. To reconcile these findings with the established Fourth Dynasty date of the Sphinx, Lehner has since attributed the earliest masonry to the Eighteenth Dynasty restoration undertaken by Thutmose IV.
However, he is clearly not certain about this as in the "Complete Pyramids” (p128-129) Lehner provides a profile of the Sphinx showing the distribution of the various phases of masonry. In the key, against the colour for the oldest large block masonry (Phase 1 - an orange brown colour) Lehner places a question mark against the entry "18th Dynasty"!
My view on this is that on the basis of style, Lehner was quite happy to see this Phase I masonry as Fourth Dyn. But when he sought proof and, to his consternation, he did n't find it, he then had to manipulate the issue....
A little later, in the "Abstract for the First International Symposium on the Great Sphinx" (1992) Hawass said: "It seems that the Sphinx underwent restoration during the Old Kingdom because the analysis of samples found on the right rear leg proved to be of Old Kingdom date."
But he's since changed his view. In his recent book(let) "The Secrets of the Sphinx - Restoration Past and Present"(1998), Hawass suggests that, when clearing the Sphinx enclosure, Thutmose IV found original (Old Kingdom) blocks -which had fallen off - and he simply put them back in place. The theory continues .... as a consequence of the blocks falling off, the underlying limestone had been exposed to weathering since the Fourth Dynasty. For convenience lets call this the Thutmoside Restoration Theory (TRT).
On the face of it this sounds reasonable, although impossible to prove - but there are a few flaws in this argument:
1 Unless ALL the blocks had fallen off for Thutmose to replace, Lehner should have found at least one or two blocks still in their original position, with little or no weathering under the block. Although Lehner does n't go into detail on the number and location of the blocks he removed when examining for tool marks under the Phase 1 masonry, he seems to have examined sufficient blocks to have satisfied HIMSELF that "....in all cases..." the limestone under the masonry was weathered.
2 From p128-9 of the "Complete Pyramids" it is evident that it is possible to identify Phase I stones that have been re-cut and replaced - see the pink shading on the Key.
So I'm not sure that the TRT really stands up.
My 'take' on the situation is that a revised sequence of development, in which the Sphinx predates the Fourth Dynasty, makes it possible to reconcile the “severe erosion”, identified by Lehner, with restoration which, everyone DOES seem to agree is Old Kingdom in style.
Best
Colin</HTML>
