Thanks cynwoody, also nabbed that PDF linked on that page. His thermal idea for the loss of the facing stones is interesting, but the fact is, the facing stones on the Great Pyramid are *known* to have been still present 2000 years after its construction, and *known* to have been stripped off during the muzzie period and carted off to build Cairo. Much of the facing of Khafre was similarly stripped, and one of the caliphs, determined to demolish the Giza monuments from the Age of Ignorance put crews to work on Menkaure. After six months they’d inflicted the damage still seen today, but the estimates of the time needed for all three pyramids was in many decades, so the “work” was abandoned. Djedjefre (son and immediate successor to Khufu) had started his own pyramid at Abu Roash, n of Giza, but died while work was in progress, and his young son who succeeded him was supplanted by uncle Khafre. What remained of the unfinished pyramid at Abu Roash was picked at over the centuries, but in the 18th and 19th centuries the stones were being carted away to Cairo by the camel-load until almost nothing remained.