"[L]ime is very important and it has been shown by [(1990) Professor D.D.] Klemm: "...in the VI. Dynasty lime disappears nearly within the mortars. May this be interpreted as a variation in the accessibility of fuel [of wood] and consequently of economic potential and crisis?" ...He was talking about the regular lime that is calcined from limestone in a kiln. ...[W]e have not found any remains of kilns... to manufacture the pyramids of Cheops and Chephren. We need... 150,000 tons of lime, which means that we should have found remains of kilns. We did not... which means that the technology was different. ...[I]t was the one of ashes that contains lime... The ecological disaster came from the over-exploitation of wood... proven by the fact that just after the Great Pyramids, one gets frescoes... describing famines..."