Like Saqqara, the pyramid at Meidum is built around a [G 017/ mastaba] nucleus. But the two primary faults responsible for the gradual disintegration of the [P 001&P058 / Step Pyramid]
were corrected before they could have been apparent - wide mortar joints exposed to the sand-bearing wind eroded more rapidly, particularly at the [G 019/ quoins] where exposure was greatest. Today, lack of special attention given to the quoins is causing the pyramid to collapse at the corners. The facework of Meidum set a pattern followed by Fourth Dynasty builders. A minimum of joint was exposed to the weather and the quoins were made from high quality stones of great length, bonded alternatively to lace the external angles. Also, the core structure reflected a purposeful change. Roughly hewn stones as large as the face were laid in mortar without the coursing and bonding that would have given stability. The stones were not bonded into the [I 045 / buttresses] behind them, and if the face was removed, the core would collapse. This seems to have been what happened, but its cause is not certain. The rubble mound may be leftover material from a demolition rather than what is generally accepted as a dramatic collapse during construction.
