The Tura quarries (or Maasara quarries) lie south of Cairo on the eastern shore of the Nile, about 13-17km from Giza. These quarries yield limestones of a very high quality - white, very fine-grained, not very porous and somewhat harder than the limestone from Giza. Tura limestone can easily be cut and formed but when being exposed to air it hardens after a certain time. Because the stones weather to a slightly yellowish tone, they were extracted already during the time of building the pyramids from layers deep down, and even from underground. The whole area where the quarries lie is almost entirely stratified horizontally, so the stones are relatively easily extracted. The stone layers are 0.8 to 1.5m thick and separated by small clayey layers. This is the reason, why the blocks can be detached from the bedrock simply by lifting them up.