Dahshur, Bent Pyramid

Sneferu can claim two, probably three, distinct and innovative designs; Meidum, probably attributed to Sneferu, is the transition from a step pyramid to a true pyramid. Its eight internal step phases was “set in inward-inclined layers” and “surrounded a tower like construction at the center”. The final layer was horizontal and provided the final smooth-sided form. It was added after the Dahshur Bent pyramid was abandoned, possibly because Sneferu’s age and the need for a practical tomb. The burial chamber, which was at ground level, was the first to use corbelling and the passage was elevated upward and exited on the north face (which allowed new layers to be added without excavating new passageways).

The old step pyramids, such as Djoser's at Saqqara)  had faces that sloped about 72° to 78°. There is evidence within the core of the Bent Pyramid that it began as a far smaller pyramid with a slope of about 60°. But structural problems with subsidence soon set in. Emergency measures took the form of a girdle around the base of the pyramid, forming a slope of just under 55°. These early stages were constructed using the traditional method of laying the courses with the stones sloping inward. Even at the reduced angle there were still major problems until, about half way up the courses began to be set horizontally. It had become clear that the inward-leaning courses (accretion), far from aiding stability, actually increased the downward stresses.
 

The Bent Pyramid was then continued at a slope of around 43° to 44°, giving it a pronounced bend. It may have been at this point, before the upper part was finished, that the decision was taken to begin a new pyramid at North Dahshur. Around the same time, perhaps the 30th year of Sneferu's reign according to Stadelmann, work also began on the satellite pyramid.
 

Other changes happened. Both core stones and casing stones are larger - the casing ones very much so - than in the 3rd-dynasty pyramids. However, no great care was taken to lay the internal masonry neatly. Substantial spaces between the stones are simply filled with limestone debris and even tafla in places. Gypsum mortar was just beginning to be used more frequently, which, unlike the desert clay mortar, had to be specially prepared using fuel. It was this combination of a lack of good mortar, carelessly laid blocks and, most importantly, the unstable desert surface, that caused the structural problems.
 

The Bent Pyramid is unique in having two internal structures, with entrances on the north and west sides. From the north side a long, sloping passage leads to a narrow antechamber with an impressive corbelled roof. The burial chamber, also corbelled, is above this antechamber and was perhaps reached by a stairway or ladder. All this building, plus a vertical shaft on the precise central axis of the pyramid, would have taken place in a trench sunk into the original desert surface.
 

The second passage runs from the west side of the pyramid, through portcullis blocking systems, to another burial chamber, again with a corbelled roof. This is at a higher level than the first. Here once again, structural instability is evident as the chamber was completely shored up with balks and scaffolding of great cedar beams. Some time after both chambers were constructed, a connecting passage was made between them. It was definitely built later as it was hacked through the masonry by someone who knew exactly where the two chambers were.
 

At the centre of the eastern side of the Bent Pyramid is a small chapel. As at Meidum the contrast between this tiny structure and the giant pyramid is very striking. Stadelmann points out that the small chapels of both Meidum and the Bent Pyramid were not part of the development of the large mortuary temples, rather they were intended to be simple shrines for pyramids that Sneferu completed as cenotaphs.

Initially the Bent Pyramid's chapel was a very simple affair composed of two walls of high-quality Tura limestone roofed with slabs, which was expanded by mudbrick walls. Within it was an offering place consisting of a slab that took the form of the hieroglyph for offering, 'hetep', a stylized loaf of bread on a reed mat. Behind this, two round-topped stelae, the stumps of which remain, were formerly inscribed with the names of Sneferu.

A causeway, also with walls of Tura limestone, ran from the pyramid complex to what is often called the first valley temple - a beautiful small, rectangular structure. On the back wall were six statues of Sneferu striding forth. In front of and, curiously, blocking these statues were two rows of five rectangular pillars. A courtyard beyond had walls carved the earliest representations of the estates of the king bearing produce towards the statues of Sneferu.

This structure is in fact a combination of both mortuary and valley temple, with features that are developed later in both. It has the court, pillars and architectural statues found in later mortuary temples, and it is situated about halfway down to the valley. A second causeway probably ran from this to a dock or landing-stage.
 

The internal structure is in some ways an abbreviated version of the Great Pyramid's, with a descending and an ascending passage. A small notch in the ascending passage, where it increases in height to a miniature Grand Gallery, adds weight to the supposition that that structure in the Great Pyramid was indeed intended for the storage of plugging blocks. A wood piece fitted into the notch could be pulled by rope to release the plugs. Just as in the South Tomb of Djoser, the burial chamber of the satellite pyramid is far too small to have contained a human burial. It may instead have been for the ritual interment of a statue of the king.
 

On the east side of the pyramid was an offering place with two more round-topped stelae inscribed with Sneferu's name.
 

The cult of Sneferu
By contrast with the pyramid-building kings of Giza, who seem to have been entirely ignored by Egyptians of the Middle Kingdom, the cult of Sneferu took root and prospered in succeeding periods. It was at the valley temple of the Bent Pyramid that this cult was focused. Why this was so is an interesting question. Perhaps it was because here at the Bent Pyramid we have a fully completed complex. Although Sneferu was probably not buried here, his name was completed on various stelae and so this was where his life continued. Ironically, this was also the pyramid complex that ran into severe structural problems and tested the builders' nerves to the greatest extent.
 

Source: The Complete Pyramids; Mark Lehner; Thames and Hudson; 2000 (possibly the best all-round book available on Pyramid)