The Linear Ramp Theory
Ramps are known to have been used at multiple sites across Egypt to build smaller pyramids. A single linear ramp that would have slowly increased in size as the Pyramids were constructed is the simplest explanation available.
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The Roman Greek writer Diodorus Siculus (1st century BC) claimed that the Egyptians used ramps because they had not yet invented cranes needed to lift the blocks.  An external ramp is the most likely method used by the Egyptians. Simple linear ramps have been found at other sites in Egypt, and were used to construct other smaller step-style pyramids, such as the pyramid of Sekhemkhet at Saqqara.  The easiest way of constructing a pyramid is to create one straight ramp leading up to the pyramid out of rubble, stone, or earth, supported by wooden scaffolding. This ramp can be adjusted for height as the building continues. The ramp would be wide enough to accommodate the growth of the pyramid. A long-wide ramp would be short enough and shallow enough to allow for the 60-ton blocks used in the King’s chamber. A linear ramp is a simple solution that is supported by archaeology at other pyramid sites in Egypt.
The linear ramp theory has been rejected by most modern archaeologists and engineers. The ramp would need to be more than 1.5km long to stay at the gradient needed to roll the blocks uphill. This would make the ramp bigger than the pyramid itself by volume. It would have been continuously rebuilt to adjust the height, which would have made the process extremely time-consuming.  The ramp would have been huge, but there is no evidence for such a large ramp. There is also a quarry and two cemeteries blocking three of the pyramid sides. Although simple ramps may have been used at some sites in Egypt, they were only used for small pyramids. By some estimates, an earthwork ramp is only structurally stable at a height of up to 120 meters. It would need extensive scaffolding or stone blocks to support it in order to reach the heights needed to build the pyramids. There are many problems with the linear ramp model. It would have been impractically long and structurally unstable. There is little evidence for such a long ramp, and no space to build one.
[P1] Archaeological and written evidence suggests ramps were used [P2] One straight ramp, adjusted for height is the simplest least intrusive way to build a pyramid [C] A single ramp was used to build the pyramids
Rejecting the premises