Bent Pyramid

The Bent Pyramid is an ancient Egyptian pyramid located at the royal necropolis of Dahshur, approximately 40 km south of Cairo, built under the Old Kingdom Pharaoh Sneferu (c. 2600 BC). A unique example of early pyramid development in Egypt, this was the second pyramid built by Sneferu.

The Bent Pyramid rises from the desert at a 54-degree inclination, but the top section (above 47 m) is built at the shallower angle of 43 degrees, lending the pyramid a visibly "bent" appearance.

Overview
Archaeologists now believe that the Bent Pyramid represents a transitional form between step-sided and smooth-sided pyramids. It has been suggested that due to the steepness of the original angle of inclination the structure may have begun to show signs of instability during construction, forcing the builders to adopt a shallower angle to avert the structure's collapse. This theory appears to be borne out by the fact that the adjacent Red Pyramid, built immediately afterwards by the same pharaoh, was constructed at an angle of 43 degrees from its base. This fact also contradicts the theory that at the initial angle the construction would take too long because Sneferu's death was nearing, so the builders changed the angle to complete the construction in time. In 1974, Kurt Mendelssohn suggested the change of the angle to have been made as a stability precaution in reaction to a catastrophic collapse of the Meidum Pyramid while it was still under construction.

The reason why Sneferu abandoned the Meidum Pyramid and its Step Pyramid may have been a change in ideology. The royal tomb was no longer considered as a staircase to the stars; instead, it was served as a symbol of the solar cult and of the primeval mound from which all life sprang.

It is also unique among the approximately ninety pyramids to be found in Egypt, in that its original polished limestone outer casing remains largely intact. British structural engineer Peter James attributes this to larger clearances between the parts of the casing than used in later pyramids; these imperfections would work as expansion joints and prevent the successive destruction of the outer casing by thermal expansion. Another obvious reason is that the steep slope made stone robbery too risky and difficult.

The ancient formal name of the Bent Pyramid is generally translated as (The)-Southern-Shining-Pyramid, or Sneferu-(is)-Shining-in-the-South. In July 2019, Egypt decided to open the Bent Pyramid for tourism for the first time since 1965. Tourists are able to reach two 4600-year-old chambers through a 79 m narrow tunnel built from the northern entrance of the pyramid. The 18 m "side pyramid", which is assumed to have been built for Sneferu's wife Hetepheres will also be accessible. It is the first time this adjacent pyramid has been opened to the public since its excavation in 1956.

Construction phases
The Pyramid underwent three construction phases. In the first construction phase, a steep pyramid with a base length of 157 m and an inclination angle of approximately 58° (possibly even 60°) was planned. If the pyramid had been completed in this form, it would have reached a height of around 125 m, but given the knowledge of ancient techniques and the comparison with completed pyramids, such a steep pyramid was probably not a realistic option and did not exceed only few stone layers. Due to the good overall degree of preservation of the pyramid, this phase can only be proven indirectly through offset points around 12.70 m from the entrance in the lower descending corridor and at around 11.60 m in the upper descending corridor. In the second phase, the builders reduced the angle of inclination to 54°. This increased the base length to 188 m. Here, too, inclined wall layers were used as in the step pyramids, because masons were not able to produce trapezoid stones at this phase. While step pyramids were built in ring-shaped shells of slant layers, the turn to undivided masonry made horizontal layers more practicable. If the inclination of 54° had been maintained, it would have reached a height of 129.4 m and a volume of around 1,524,000 cubic meters. The Bent Pyramid would therefore be the third highest pyramid in the world. However, this inclination was not continued beyond a height of 49 m. The masonry of this phase is faced with fine Tura limestone. In the third construction phase, the angle was reduced to 43° and, like in the Red Pyramid and all successive pyramids, the masonry was laid in horizontal layers. The slope reduction created the unique kink that is not found in any other pyramid. Due to the lower inclination angle of the upper part, the total height was reduced to 105 m. The total volume was 1,440,808 cubic meters. The upper area also has a cladding of fine Tura limestone.

Recent conclusions rather speak against a connection between the change in slope and structural defects. It is rather doubtful that a reduction in weight was a relevant criterion for a structure of almost closed mass. The early decision against the 60° inclination initially envisaged rather suggests that geometric aspects were the decisive factor in the gradient change. Following the assumption of tangential construction ramps inclined up to 10° as the simplest form of ramp, the fact edge lengths became smaller as the height increased made it increasingly difficult to keep the gradient low. This could be compensated for by reducing the ramp width to around 3 m, which was sufficient for pairs of train crews, but even for such narrow ramps the geometric volume could not provide enough space when the gradient was too steep. Models and abstract calculations were not possible in that time. It must therefore have become clear to the construction managers halfway up that ramp structures would not be feasible when maintaining this gradient. In fact, all completed pyramids (first the Red, then the Great Pyramid) never exceeded the maximum gradient of 53°.

Interior passages
The Bent Pyramid has two entrances, one fairly low down on the north side, to which a substantial wooden stairway has been built for the convenience of tourists. The second entrance is high on the west face of the pyramid. Each entrance leads to a chamber with a high, corbelled roof; the northern entrance leads to a chamber that is below ground level, the western to a chamber built in the body of the pyramid itself. A hole in the roof of the northern chamber (accessed today by a high and rickety ladder 15 m long) leads via a rough connecting passage to the passage from the western entrance.

The western entrance passage is blocked by two stone blocks which were not lowered vertically, as in other pyramids, but slid down 45° ramps to block the passage. One of these was lowered in antiquity and a hole has been cut through it, the other remains propped up by a piece of ancient cedar wood. The connecting passage referenced above enters the passage between the two portcullises.

A particular feature in the chambers are a row of original cedar beams that were interpreted by many as a reaction on structural problems. In contradiction to that, Edwards argues the cedar beams rather had been part of the funerary support structure and, some of them bedded in mortar, could not have any structural function.

Causeway
A causeway leads from the Bent Pyramids' northeast toward the pyramid with the valley temple. The causeway was paved with limestone blocks and had a low limestone wall on each side. In fact, there may have been a second causeway that lead down to a dock or landing stage, but there is no excavation that can prove this assumption yet.

Pyramid temple
On the east side of the pyramid there are the fragmentary remains of the pyramid temple. Like the pyramid temple of the Meidum pyramid, there are two stelae behind the temple, though of these only stumps remain. There is no trace of inscription to be seen. The temple remains are fragmentary but it is presumed to be similar to that of the Meidum temple.

Satellite pyramid
A satellite pyramid, suggested by some Egyptologists to have been built to house the pharaoh's ka, is located 55 m south of the Bent Pyramid. The satellite pyramid originally measured 26 m in height and 52.80 m in length, with faces inclining 44°30'. The structure is made of limestone blocks, relatively thick, arranged in horizontal rows and covered with a layer of fine limestone from Tura. The burial chamber is accessible from a descending corridor with its entrance located 1.10 m above the ground in the middle of the north face. The corridor, inclined at 34°, originally measured 11.60 m in length. A short horizontal passage connects the corridor with an ascending corridor, inclined at 32° 30', leading up to the chamber.



The design of the corridors is similar to the one found in the Great Pyramid of Giza, where the Grand Gallery takes up the place of the ascending corridor. The corridor leads up to the burial chamber (called this despite that it most probably never contained any sarcophagus). The chamber, located in the center of the pyramid, has a corbel vault ceiling and contains a four metres deep shaft, probably dug by treasure hunters, in the southeast part of the chamber.

Like the main pyramid, the satellite had its own altar with two stelae located at the eastern side.

Man-made landscape
As the first geometrically "true" pyramid in the world, the Bent Pyramid is also connected to the surrounding landscape. Nicole Alexanian and Felix Arnold, two distinguished German archeologists, provided a new insight toward the meaning and function for the Bent Pyramid in their book named The complex of the Bent Pyramid as a landscape design project. They noticed that the sites of the Bent Pyramid sits aside in the middle of a pristine desert area instead of fertile area near the Nile River like all the other pyramids, and concluded the landscape surrounding the Bent Pyramid is man-made. When the archaeologists observed the landscape closely, the plateau of the pyramid seemed leveled artificially and nearby escarpment and trenches were all made by human beings. Moreover, there were a few traces left indicating a build-up of garden enclosure. The impact of humans on the landscape is also represented by the presence of a wadi channel connecting the Bent Pyramid to a harbor, which shows a distinct difference between the southern and northern side of the channel. It shows a substantial difference in level with regards to the finding. The slope of southern wadi channel seemed to have been rectified when the archaeologists compared it to the natural and twisted northern side. Arne Ramisch supported this idea by providing evidence that displays a low correlation of fraternal patterns of channel and natural topography in the environs, which is southern side of wadi, of the Bent Pyramid.

The purpose of this man-made construction might hold mythical meaning and ritual function. Based on available evidence, garden enclosure and water basins both are the counterparts of funeral rites which indicates a regular practice of rituals at Dahshur. However, there is also the implication that the garden closure helped to create a satisfactory living environment in the desert. Other than that, the leveled plateau, the quarrying trenches on the western and southern sides of the pyramid, and the nearby smaller tombs cooperate together to emphasize the monumentality of the Bent Pyramid, aiding by its long distance from the surrounding structures. These features represent the imprinting social hierarchy in the creation of this landscape, which furthermore represents the power of Egyptian King at that time. Alexanian and Arnold describes this construction in a concise phrase: an artificial mountain erected within an artificial landscape.