Ancient Egypt comprised four dominant physiographic provinces: the Nile Delta, the Nile Valley, the Western Desert, and the Eastern Desert. These incorporate many landform features, including mountain ranges (Red Sea hills), desert oases (Kharga, Dakhla, Bahariya, Farafra), basins (Qattara Depression, Faiyum), wadis (Natrun, Hammamat), coastal lagoons (Burullus, Manzalah), coastal beach deposits (Mediterranean and Red Sea coasts), inland plateaus (Diffa, Gilf Kebir), inland and coastal dune fields, river terraces, geziras, and desert hills. Sedimentary histories of these features range from Precambrian to Quaternary and, specifically for the exposed sedimentary units, from the Mesozoic Tethys Sea erosion/deposition to the Recent pre-Aswan Dam sedimentation.

These landforms and their associated sediments played diverse roles in the culture of ancient Egypt. Of great significance was the symbolic dualism, composed of complementary opposites, embodied in the stark contrast between Nile alluvium and desert. The rich agricultural land, kmt (“black land”), exemplified fecundity and life; the arid, barren desert, dšrt (“red land”), denoted sterility and death. Also symbolic and basic to Egyptian civilization was the dualistic division between the Nile Delta as Lower Egypt and the Nile Valley as Upper Egypt. Less symbolically, the various sediments also contributed to Egyptian civilization in a number of practical ways. From a basic soil classification context, Egyptian sedimentary units may be divided into coarse-grained and fine-grained sediments.

Fine-Grained Sediments (Silts and Clays).

Silts and clays served numerous cultural functions. Before the construction of the Aswan Dam, the Nile River had the most consistent yearly flooding cycle of all the great rivers of the world. Annual flooding maintained Egyptian soil productivity by depositing sediments that added new nutrients (organics, phosphates, nitrates, and carbonates) to the system, and by providing a downward flux in the vadose zone (the zone between surface and water table) that removed undesirable evaporitic salts. The dominant agricultural sediments, located on alluvial flats, consisted of oxidized overbank Nile silts that were distributed throughout the floodplain. Natural levees were used for agriculture and settlement. The regular yearly inundation was arguably the single most important factor in the development of ancient Egypt's unique civilization.

Two clay source types dominated Egyptian ceramic production: (1) the terrigenous-alluvial-lacustrine muds/clays, most importantly Nile silts, also wadi and desert clays; and (2) the calcareous sediments, especially marl muds, clay limestones, and some lag deposits.

The first source type included ubiquitous unconsolidated Pleistocene/Holocene brown silty muds (clay + silt) of the Nile alluvial floodplain consist of oxidized facies that are terrigenous-alluvial and lacustrine. Reduced sediment facies are composed of gray-black reducing muds from lagoonal, fluvio-lacustrine canal, and buried paleo-fluvio-lacustrine deposits; these generally contain a higher clay content than the oxidized sediments. Silty to sandy muds form in wadis, in response to local processes of soil formation (pedogenesis) during valley aggradation and are generally associated with older river terraces. Desert clays also occur as gray kaolin clays from Lower Cretaceous Nubian Sandstone deposits and closed-basin lacustrine deposits (Pliocene estuarine “plastic” clays from el-Kharga).

The second source type consisted of calcareous sediments derived from Cretaceous to Recent consolidated and unconsolidated facies: Upper Cretaceous to Paleocene variegated shales, phosphate formations (Dakhla), chalks, mudstones, and calcareous shales; Eocene marls; Oligocene and Miocene calcareous shales and clayey limestones; yellowish lag clays from the alteration of limestones (tafl); and Pleistocene paludal facies (marsh sediments) of calcareous silty or clayey fine sandy muds. They originate from fresh-water, brackish-water, marine, or K-horizon (caliche, calcrete) desert soils. When present in any quantity in ceramic pastes, they impart a distinctive calcium carbonate and mudstone texture to the fabric.

Mud brick was the most common building material in ancient Egypt. Mud-brick source sediments were dominated by the ubiquitous alluvial and fluvio-lacustrine, fine-grained, oxidized brown Nile silts; reduced black-gray canal and harbor-lacustrine muds; and yellowish aeolian, quartz-impregnated, fine-grained wadi alluvium. These source sediments were utilized alone or mixed with other organic and inorganic materials, such as sand, straw, and dung, to produce mud bricks. Mud plasters, mud mortars, and terre pisée, also important for construction, were produced from the same materials.

Coarse-Grained Sediments (Sands and Gravels).

Coarse-grained sediments were also exploited for various purposes, including construction, use as abrasives, glass production, and use as ceramic temper. Architectural foundations generally consisted of aeolian sands or alluvial gezira sands and gravels used for leveling and load-bearing prior to construction. In sedimentary environments such as the Nile Valley and Delta, the dominant sediment consisted of silts containing montmorillonite clay. Montmorillonite holds up to about twenty-eight times its weight in water. This capacity generally wreaks havoc with stone construction because seasonal wetting and drying cause alternate swelling and shrinking of the ground. Foundation sands and gravels aid with wall stabilization under these conditions. Foundation sands also served as a religious symbol, representing the primeval mound of first creation. In addition, sands and gravels were used in construction ramps and for tomb-shaft fill; sand was used in various mechanisms for moving monolithic stones.

Alluvial, marine, and dune sands were used as abrasives for a variety of purposes, including stone-quarrying and stone-working. These sediments are naturally well sorted and composed mostly of quartz (Mohs Scale of Hardness, 7).

Various sand sources (alluvial, marine, aeolian) were used in glass production. These natural sands were mixed with additional calcite (limestone or mollusk shells), plant ash, coloring materials, and natron to make glass.

A variety of materials were used as ceramic temper, most notably sands, gravels, and rock fragments from the following sources: (1) aeolian sands derived from inland dunes consisting of fine sand to granule-sized, very well-rounded, frosted and iron-stained clear quartz sands; (2) coastal dune sands composed of well-sorted quartz sands where the iron oxide from the surface of the older dune sands has been eroded; (3) beach sands and silts composed of moderately well-sorted, coarse silt to sand-sized quartz with secondary feldspar, heavy minerals, and large-grained muscovite mica; (4) colluvium found on and at the base of sedimentary and igneous rocks cliffs, consisting of poorly sorted admixtures of angular sedimentary, metamorphic, and igneous rock fragments, as well as rounded and frosted aeolian quartz sands and rounded and frosted quartz sands from cross-bedded dune sand-stones (colluvial sands may also contain calcrete fragments and fossiliferous biocarbonates); (5) alluvial sands and gravels from the Pleistocene geziras and Holocene Nile main and distributary channel sediments; and (6) coarse-grained brackish or fresh-water shells associated with lagoonal, marsh, and fluvial environments.

See also NATURAL RESOURCES; and NILE.

Bibliography

  • Al-'Izz, Abu. Landforms of Egypt. Cairo, 1971. Basic geology of Egypt; sediment distribution and landform evolution is presented.
  • Butzer, Karl W. Early Hydraulic Civilization in Egypt. Chicago, 1976. A groundbreaking study in the cultural ecology and the hydrogeo-archeology of the Nile Basin.
  • Butzer, Karl W. “Modern Egyptian Pottery Clays and Predynastic Buff Ware.” Journal of Near Eastern Studies 33 (1974), 377–382. Geologic clay-paste sources for pottery are discussed in relation to predynastic ceramics.
  • Butzer, Karl W., and Carl L. Hannen. Desert and River in Nubia. Madison, 1968. Summarizes the geomorphic evolution of the Nile Basin and describes major sedimentary formations.
  • Lucas, A., and J. R. Harris. Ancient Egyptian Materials and Industries. 4th rev. ed. London, 1989. The primary reference book on the subject.
  • Nordstrom, H. A., and J. Bourriau. “Ceramic Technology: Clays and Fabrics.” In An Introduction to Ancient Egyptian Pottery, edited by D. Arnold and J. Bourriau, pp. 143–190. Mainz, 1993. Ancient Egyptian ceramics are discussed in relation to paste and temper sources.
  • Said, R., ed. The Geology of Egypt. Rotterdam, 1990. A series of articles on the detailed geology and stratigraphy of Egypt, including the distribution of sediments and basement tectonics.

Maury Morgenstein and Carol A. Redmount