How did we date the construction of the Great Pyramid of Giza?

by snorlord

According to Wikipedia, the Great Pyramid was built around 2560-2540 B.C.

I was reading a book on mysticism and I found it interesting that the author argues about things like erosion (which was already addressed in this thread).

But he also claims things like "There is no proof that the building was erected by the Egyptians, for the elaborate carvings with which the burial chambers of Egyptian royalty are almost invariably ornamented are entirely lacking and it embodies none of the elements of their architecture or decoration, such as inscriptions images, cartouches, paintings, and other distinctive features associated with dynastic mortuary art. The only hieroglyphics to be found within the Pyramid are a few builders' marks sealed up in the chambers of construction [sic], first opened by Howard Vyse."

Are these differences due to grave robbers, lack of knowledge about Egyptian history on the author's part? Also, if there was documentation (work records/payments?) then that would be much more convincing too. I wouldn't normally take a mystic's word on history (e.g. he claims that there must be a secret passage in the Great Pyramid because otherwise the Pyramids could not have been used for Mysteries (a la Eleusinian Mysteries) which are core to his syncretic interpretation of ancient religions and contemporary Masonism), but I also prefer to discount claims based on actual evidence.

and it embodies none of the elements of their architecture

This is the most troubling and ignorant part for me. The Pyramids at Giza follows neatly in the evolution of dynastic mortuary architecture. The earliest structures were mastabas, monumental constructions on top of tombs. Then Imhotep, an adviser for the pharaoh Djoser, decided to add some spice to his king's tomb and stacked some mastabas on top of each other to make a "pyramid". Sekhemkhet tried to create a larger one, but it was never finished. Sneferu's architect was the first to design a "true" pyramid at Dahshur, but had to get it wrong a few times. This inspired the pyramid boom of the 4th-6th dynasties, when the large majority of known pyramids were constructed. It's rather standard archaeological practice to assume that when you find something that looks just like a bunch of other things, it's probably from the same time. If I find the body of a 1952 Chevy, it'll require more evidence to prove that it's not from the mid-20th century than that is, since we have so many other '52 Chevys lying around.

Additionally, and this may be the result of the author writing in 1928, the decorations he describes within burial chambers don't come around until later. Unas is the first king we know of to cover his burial chamber with hieroglyphic pyramid texts (one dynasty after those at Giza) and the painted tomb we often think of is from New Kingdom pharaohs centuries later. Other pyramids are also largely undercoated, such as the aforementioned Bent Pyramid.