jeudi 25 février 2021

La construction des pyramides égyptiennes selon Leslie Grinsell - 3e partie : fondations et infrastructures

illustration extraite de l'ouvrage de Grinsell

Foundations

(a) Preparation of the Pyramid Area
In certain instances, as at the pyramids of Abu Rauwâsh and Lahûn, and also at the tomb of Khentkawes at Gîza, the tomb superstructure was sited on a natural rock massif, which enabled a superstructure of the desired size to be constructed with a considerable saving of labour. In these instances the only levelling required consisted of dressing the natural rock surface for the reception of the masonry to be added.
In other cases a sloping surface has been levelled at great expense and labour in order to provide a suitable base. This has been done at the pyramid of Khephren, where the desert surface has been cut away considerably on the north-west part and built up on the south-east.
It has been suggested that the process of levelling was assisted by banking up the square base-area and flooding it, and then marking the water level on the inner sides of the bank. The plane of the base of the pyramid of Kheops slopes upwards from north-west to south-east to the extent of six inches, and this could have been caused if a slight north-west breeze was blowing at the time of the checking of the levelling by flooding.
After the levelling had been completed, the whole base area was often paved with slabs of fine white limestone. This is well seen around the base of the pyramid of Kheops, although it is thought that the paving does not extend over the whole area. Sometimes the paved base-area extends outside the pyramid to form an exposed pavement, as at the pyramid of Sesostris I at Lisht, where the paving stones were joined together by dovetail cramps.
(b) Foundation Deposits.
Our knowledge of the foundation deposits of pyramids is derived almost entirely from those of the Middle Kingdom. They consist mainly of specimens of the materials used in the construction of the pyramid complex, inscribed sometimes with the names of the king and his pyramid. Foundation tablets of brick, metal, stone and wood, bearing the name of Nebhepetrê Mentuhotpe, were found in the pyramid-temple of that king at El Deir el Bahari.
Beneath the south-west corner of the pyramid of Ammenemes I was a foundation deposit consisting of an ox-skull, some small and badly broken pottery vases and saucers, and six clay bricks. Each brick contained a tablet inscribed with names of the king and his pyramid ; two tablets were of copper, two of faience, and two of limestone.
Beneath the north-west, south-west, and south-east corners of the pyramid of Sesostris I were foundation deposits of food offerings, pottery, and bricks containing tablets of some of the materials used in the construction of the pyramid and temple. The tablets were of wood, metal, faïence, and alabaster, and were inscribed with the name and titles of the king and the name of his pyramid, ‘Sesostris Surveying the Two Lands’. From the overlapping of the different objects it was determined that the meat offerings were dropped in first, then the pottery, and then the bricks. In the south-east corner there were two deposits, one of which was probably inserted when the pyramid was completed.
The pyramid of an unknown king of Dynasty XIII, south-west of that of Khendjer II, contained foundation deposits of coarse pottery and models of copper and bronze implements.(c) Foundation Ceremonies.
Fragments of reliefs from a granite door-jamb of Khasekhemuy and from the solar temple and pyramid complex of Neuserrê, when studied in the light of more complete representations of later date (as at Edfu), provide a clear idea of the main episodes of the foundation ceremonies for a pyramid or other structure of Old or Middle Kingdom. These episodes were :
(1) Pegging the ground and stretching the cord ;
(2 ) Breaking the ground surface (usually done four times) ;
(3 ) Sprinkling of sand ;
(4 ) Making of bricks (done four times at Abu Girab) ;
(5 ) Laying the bricks.
The last two episodes may have been a survival from predynastic and Thinite times, when tombs were made of brick before the invention of stone masonry. The ceremonies appear to have been performed by the king, with the assistance of goddesses, sem-priests, ritualists and others.


The Substructure

The first step in the construction of the pyramid consisted of hewing out of the bedrock, with copper chisels, adzes, and other implements, those parts of the passages and chambers which were to be below ground level.
Good examples of these, open to the sky, are to be seen at Abu Rauwâsh and the unfinished north pyramid of Zâwyet el 'Aryân. The latter is of special interest as an example of an unfinished pyramid in which the substructure was nearly completed but the superstructure not even begun. The impressive stairway, ramp, passage, and sarcophagus chamber had been hewn out of the bedrock, and sarcophagus chamber had been paved with granite and received the fine red granite sarcophagus ; then for some unknown reason the work was abandoned.
It is well to distinguish between the ‘open trench’ substructure (Abu Rauwâsh and Zâwyet el ‘Aryân) and the ‘tunnelled’ substructure, seen in the lower passage and chamber of the pyramid of Kheops, the pyramids of Kheops’ queens, and the pyramids of Mycerinus and his queens.

(a) The Sarcophagus Chamber was usually wholly or partly in the substructure. The most important exception is the pyramid of Kheops, in which the position of the sarcophagus chamber was altered from the substructure to the superstructure in the course of building. It was generally lined with granite (Kheops and Mycerinus) or fine white limestone (as in the pyramids of Dynasties V and VI containing Pyramid Texts). The roofing was :
(1) Corbelled as in the Dynasty III pyramids at Dahshûr and Maidûm.
(2) Pointed as in the pyramids of Dynasties V and VI.
(3) False-arched with slabs placed end to end and hollowed concave on their undersides, as in the chambers of Mycerinus and Shepseskaf.
It is evident that the roofing blocks were cut to shape, arranged, and numbered before being placed in position ; indeed the roofing blocks of Djeser and Kheops have their markings and numbering still visible ; but those of Djeser were reversed in orientation when laid. In view of the great weight of superincumbent masonry which had to be borne by the roof of the sarcophagus chamber one or other of the following devices was used :
(*) Relieving chambers, as above the king’s chamber in the pyramid of Kheops.
(**) Relieving slabs, often of enormous thickness, as above most of the chambers with pointed roofs of Dynasties V and VI. Architects’ inscriptions on the walls of the antechamber and sarcophagus chamber of the tomb of Shepseskaf (Mastabet Fara’ôn) which read ‘upper side of the paving stone, true line’, almost certainly show that the walls were built before the floor-slabs were inserted.
The presence of the sarcophagus in the unfinished chamber of the north pyramid of Zâwyet el ‘Aryân, shows that the sarcophagus was dragged down the smooth rock-hewn ramp, which had a narrow stairway on each side as a foothold for the workmen, before the ramp was walled with stone slabs. That this was the usual custom is shown by comparing the dimensions of sarcophagi with those of completed passages and ramps. The sarcophagus of Queen Neit (Dynasty VI) is actually wider than the passage, while the horizontal or other passages in the pyramids of Kheops, Khephren, Mycerinus, Unis, and Pepy II are too narrow to have permitted the movement of the sarcophagus, the clearance space being either non-existent or less than 10 centimetres.
(b) The Antechamber,Serdab, Horizontal Passage and Vestibule presented no constructional problems other than those encountered in building the sarcophagus chamber.
(c ) The Portcullis Slabs of the Old Kingdom were normally of granite and let down vertically, although that in the Dahshûr pyramid of Snefru was let down obliquely. During the Middle Kingdom the portcullis slabs were frequently of quartzite and were nearly always slid transversely across a slightly inclined gap over the passage which they were intended to block. Before being let down, the Old Kingdom portcullis slabs were supported on piles of stones, as seen in unfinished mastaba tombs of Dynasty III at Maidûm. As a protection for the tomb, portcullis slabs had little effect as the robbers always worked their way under, above, or around them.
(d) The Ramp normally slopes downwards from the entrance to the horizontal passage of the pyramid. The angle of slope was usually between 15 and 30 degrees, although it was only 10 degrees in the pyramid of Ammenemes I at Lisht. Two important reasons for the downward-sloping ramp were to facilitate the lowering of the sarcophagus and canopic chest, and to assist in the blocking of the means of ingress by sliding down monoliths after the deceased had been interred. The pyramids of Dynasties III and IV had their entrance high up in the superstructure, and the ramp was therefore at least partly in the superstructure. From Dynasty V onwards the whole length of the ramp was in the substructure. In either case it had nearly always a flat roof, and the walls and roof were often lined with slabs of red granite or limestone.


extrait d' Egyptian Pyramids, 1947, par Leslie Grinsell (1907-1995), archéologue et conservateur de musée anglais. Durant la Seconde Guerre mondiale, il a rejoint la Royal Air Force et a servi en Égypte, où il s'est familiarisé avec les vestiges archéologiques de l'Égypte antique.