[79] The bedrock reaches a height of almost 6 metres (20 ft) above the pyramid base at the location of the Grotto.[80]
Along the sides of the base platform a series of holes are cut in the bedrock. Lehner hypothesizes that they held wooden posts used for alignment.[81] Edwards, among others, suggested the usage of water for evening the base, although it is unclear how practical and workable such a system would be.[78]

Materials
The Great Pyramid consists of an estimated 2.3 million blocks. Approximately 5.5 million tonnes of limestone, 8,000 tonnes of granite, and 500,000 tonnes of mortar were used in the construction.[82]
Most of the blocks were quarried at Giza just south of the pyramid, an area now known as the Central Field.[83] They are a particular type of nummulitic limestone formed of the fossils of thousands of prehistoric shell creatures, whose small disc form can still be seen in some of the pyramid's blocks upon close inspection.[84] Other fossils have been found in the blocks and other structures on the site, including fossilized shark teeth.