What are the Egyptian pyramids built of?

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

In recent years, waves of pseudoscientific fabrications about ancient Egyptian construction methods have swept across the Internet and other media outlets: it has been argued without justification that stone building blocks are concrete structures.

Rice. 1. The pyramids of Menkaur (Mikerin) and Khafre (Khafre) in Giza, built of limestone blocks. At the base of the Menkaur pyramid (foreground) are chunks of granite and granodiorite brought from the Aswan region. Photo from a discussed article in the Encyclopedia of Egyptology.

For the construction of pyramids, as well as tombs and mastabas in ancient Egypt, they preferred to use relatively soft and widespread rocks - limestone and sandstone, as well as anhydrite and gypsum. James Harrell for the Encyclopedia of Egyptology, published online by the University of California, Los Angeles, has provided an impressive overview of 128 ancient Egyptian quarries. There were probably many more of them, but some are still not discovered, while others were destroyed in subsequent eras.

In recent years, waves of pseudoscientific fabrications about ancient Egyptian construction methods have swept across the Internet and other media outlets: it has been argued without justification that stone building blocks are concrete structures. The source for such assumptions was a series of publications by the French chemist Joseph Davidovits (Davidovits, 1986 and others), which argued that the blocks in the pyramids were poured in situ from a solution composed of crushed clayey kaolinite limestone, common in the Giza region, lime and soda. Of course, geologists and paleontologists who have studied the composition and structure of Egyptian blocks have repeatedly noted that they are processed blocks of natural sedimentary deposits, and by no means concrete fill (see, for example, Jana, 2007), but, alas, these are the most stupid ideas nowadays it is customary to exalt to the shield.

Geologist James Harrell of the American University of Toledo, Ohio, has not only meticulously mapped 128 ancient quarries in what is now Egypt and North Sudan (Fig. 2), but also figured out which epochs were preferred to certain construction sites. materials in various parts of the Ancient Egyptian state.

Rice. 2. Map of the ancient Egyptian quarries. Red circles show limestones, black squares - sandstones, green triangles - gypsum. Drawing from a discussed article in the Encyclopedia of Egyptology.

The Egyptians used stone blocks and slabs not only for the construction of large-scale stone structures, but also fortified and revetted buildings made of adobe bricks with them - palaces, fortresses, storehouses, residential buildings. The main building materials were relatively soft, that is, easy-to-work, sedimentary rocks - limestones and sandstones (Fig. 1, 3). If the limestones were almost pure calcium carbonate, then the sandstones consisted mainly of quartz sand grains with an admixture of feldspars. The Egyptians called limestone "a good white stone from Tura-Masar" (Tura-Masara, or Mazar, is one of the regions where the stone was mined), and sandstone - "a beautiful light hard stone." It is, indeed, harder than limestone.

Rice. 3. (a) An open limestone quarry for the Khafre pyramid at Giza, where the markings are preserved (Fig. 2, 4). (b) A limestone adit at Ko el Kebir with support columns (Fig. 2, 64). (c) Quarry to extract sand blocks at Nag el Khosh (Fig. 2, Quarry 8). Photos from a discussed article in the Encyclopedia of Egyptology

Since the time of the Old Kingdom, limestone has become the main stone of Egyptian builders, since it was this rock that was widespread along the Mediterranean coast and the Nile Valley from Cairo in the north to Esna in the south (Fig. 2, 3a, b). For example, one of the Great Pyramids - Khafra - in Giza was built from limestone, which was mined right behind it (Fig. 3a). Sandstones came to the surface along the banks of the Nile south of Esna (Fig. 2, 3c). They were used less often: in the Old Kingdom, a dynastic tomb in Hierakonpole and a small pyramid in Nagada were erected from sandstone. Nevertheless, despite the difficulties with transportation, in the era of the New Kingdom, it is sandstones that are more resistant to destruction that become the main building materials - most of the temples in Thebes, some of the temples in Abydos, the Aton temple in El Amarna. In the Sinai Peninsula and in the western oases, the choice of stone for construction depended on what could be obtained from the nearest quarry.

Less often, and probably for special purposes, both practical (to strengthen the building) and ceremonial (to pay tribute to the pharaoh or priest), the Egyptians mined and processed very hard granites and granodiorites (Fig. 1) or drain (highly silicified) sandstones and basalts. (Basalt and granodiorite are igneous rocks, granite has a complex metamorphic origin.) Two types of salts were mined on the coast of the Red Sea, suitable for construction - anhydrite (calcium sulfate) and gypsum (hydrous calcium sulfate). It is interesting that the name of the rock and mineral - "gypsum" - through the Greeks goes back to the Egyptians, although they could borrow it from the Akkadians. For cladding, the Egyptians also used travertine, or calcareous tuff, known as "Egyptian alabaster".

So that between large blocks in buildings there were no gaps, as well as voids and chips, the Egyptians in the Preynastic period invented their own type of gypsum-based solution. When this mineral is heated to 100-200 ° C, it loses some of its water and turns into a hemihydrate - burnt gypsum. When mixed with water, this substance re-crystallizes in the form of gypsum and quickly solidifies. In its pure form, burnt gypsum was more often used to create surfaces along which reliefs were carved, and when it was required as a filler, sand was added. A real limestone-based cement slurry appeared only under the Ptolemies (IV century BC).

Of the 128 known quarries, 89 were mined for limestone, 36 for sandstone, and 3 for gypsum and anhydrite. Although, as a rule, the stone for construction was taken in the nearest quarry, but for facing work, distant quarries could also be used if less fractured limestone of pleasant shades and textures could be found there, for example, limestones from the quarries of Tura and Masara in period of the Ancient and Middle Kingdom. And for the temples in Thebes, sandstone was delivered over a hundred kilometers. Usually, the stone was quarried in open-pit quarries, but when material of a special quality was required, adits were drilled up to 100 m deep into the cliff (Fig. 3b). With the help of picks and chisels (copper, then bronze, later iron) and stone sledge hammers, rectangular blocks were cut out (Fig. 4).

Rice. 4. (a) Plan of the temple inscribed on a support column in the Jbel Sheikh Said adit (Fig. 2, Quarry 33). (b) Blocks of limestone remaining in the “Queen Ty” quarry (Fig. 2, Quarry 35). Photos from a discussed article in the Encyclopedia of Egyptology

The map of quarries, compiled by James Harrell, is accompanied by a list, which provides information about the rocks that were mined in each of them: the name of the formation, its age, features of structure and composition, the most characteristic fossil organisms, as well as buildings that are probably, were erected from blocks mined in this quarry, and the time when work was carried out in it. For example, for the Khafre pyramid, limestone blocks were cut not far from it in a quarry (Fig.3a), which exposed the Middle Eocene Observatory Formation (approximately 45 Ma), which is normal marine sediments with abundant shells of giant protozoa - foraminifera nummulitides, as well as microscopic operculinids, globigerinids and other foraminifera; the remains of sea urchins are found there; the structural features of the limestone indicate that it formed no deeper than the baseline of storm erosion.

It is the mineralogical composition of rocks (Fig.5), their structure, texture and other petrographic features, and for sedimentary rocks - also the composition of the fossil fauna - make it possible to accurately determine from which quarry the future elements of specific buildings were removed. The unique features of the sea basin or a small part of it are reflected over time in the sedimentary rocks formed there and freeze in them forever, even if fragments of these rocks become building materials.

Rice. 5. Samples of ground sections of rocks used as building material in Ancient Egypt. The upper row is granite and granodiorite; second row - gneisses, gypsum and limestone; the third row is limestone; fourth - limestone and sandstones; H6, H7, O1, L6, L9, L21, L25, L75, L91, S3, S9b - designations of quarries on the map. From the book Harrell, 2009.

Also, according to petrographic and paleontological features, at one time they were looking for quarries, where limestone was mined in the Middle Ages for the construction of temples of Ancient Russia and France, when they began to restore them. Because even very similar limestone blocks taken from different quarries have a slightly different composition, including a chemical one, which can provoke increased erosion in the restored wall at the junction of the "patches" with old stones.

See also:

1) J. Davidovits. X-ray analysis and x-ray diffraction of casing stones from the Pyramids of Egypt, and the limestone of the associated quarries / R. A. David // Science in Egyptology Symposia. Manchester: Manchester University Press. 1986. P. 511-520.

2) D. Jana. Evidence from detailed petrographic examinations of casing stones from the Great Pyramid of Khufu, a natural limestone from Tura, and a man-made (geopolymeric) limestone // Proceedings of the 29th Conference on Cement Microscopy, Quebec City, PQ, Canada, May 20 –24. 2007. P. 207-266.