Geography

Geography and Geology of the Eastern Desert

Red Sea HillsContents

 

Geography

Egypt is a land of contrasts – the fertile Nile Valley, the arid desert regions, the lowland Sahara and the highland Red Sea Hills.  In spite of their apparent desolation, the deserts have frequently played an important part in Egyptian economic life. 

At the end of the Pleistocene, as the glaciers began to retreat, post-glacial global warming provided more humid periods in Egypt from around 10,000bp to around 3500bp. The deserts were more like the Sahel or savannah areas, with ephemeral water supplies and grass/shrub vegetation offering resources for animals and humans to exploit.  Even after the increasing aridification at the end of the mid Holocene, the deserts continued to be exploited during moister periods.

In the Western Desert a semi-circle of oases offered refugia to those driven out of the desert, and in the Eastern Desert natural stone and mineral resources continued to attract quarrying and mining expeditions and settlements.  Nomads have continued to occupy the Eastern Desert up until modern times, surviving on the sparse opportunities offered by sporadic orographic rainfall attracted by the Red Sea mountains.

Satellite EgyptThe Eastern Desert extends from the eastern edges of the Nile Delta down into the Sudan, between the Nile and the Red Sea.  It  measures c.1100km from north to south, and 225km (on average) from east to west, an area of over 222,000sq. km (Morrow and Morrow 2002, p.11).  It forms around 22% of Egypt’s surface area, but is undeveloped due to the limited availability of water (Moneim 2005, p.416).

The wadis that bisect the mountains and the plateau of the Eastern Desert provided natural routes which have been used at different times by hunters, pastoral nomads, caravans, military personnel and industrial work teams (ancient and modern) and tourists.  Most wadis are orientated east to west (e.g. Wadi Hammamat), but some head broadly south to north (e.g. Wadi Qena).  The best known of the east-west wadis is the Wadi Hammamat.  This extends from Qift (ancient Coptos) in the east to Quesir on the Red Sea coast in the west.  It was paved in modern times, which has made it one of the most popular east-west routes.  Prior to the paving of the Wadi Hammamat, the Wadi Qash to the south was also a well used route used for traveling between Quseir and Qift, but via Bir Kareim, Bir Qash and Laqeita (where the Wadi Qash route and Wadi Hammamat meet). To the north, the Wadi Araba connects the Nile, just south of the Faiyum, to the Red Sea.

A good infrastructure of roads was required to support both industrial activities and trade with coastal areas.  Many of these routes are no longer visible and their presence cannot be detected, although contemporary documentation confirms their existence, and the existence of others is implicit simply because of the need to connect certain key sites.  Other routes are still active and important today. The route provided by the Wadi Hammamat was of major importance, providing acess both to the Red Sea and to the quarries along the Wadi Hammamat itself.  The Wadi Hammamat route in fact also incorporates the Wadi Atulla and Wadi Gasus.  During the Ptolemic Period, sea trade with with Arabia and Asia raised the importance of many of these routes.   As new harbours were built, more roads were cleared to connect important towns and ports, via wells and other water sources.

The Eastern Desert is still occupied today by a dwindling number of Bedouins, made up of a number of different groups, with different subsistence strategies including both sedentary and nomadic ways of life.  Many are now moving to more modern ways of making a living, finding employment in tourism and industry.

Today, the Eastern Desert and the Red Sea Coast are popular among tourists for principally three reasons.

  • The least of these is probably the various inscriptions from the Predynastic and Dynastic Periods, along with the Roman forts, hydreuma, way stations and the few obscure temple ruins that dot the landscape.
  • More popular, and becoming more accessible to tourists, are the several Eastern Desert monasteries of St. Anthony and St. Paul. These have seen much interest of late.
  • However, the most popular destination for tourists have little to do with Egyptian history. They are the Red Sea resorts, of which Hurghada is best known. Other popular coastal resorts are upscale el-Gouna, and of late. Along the coast, there are other smaller resort communities, many specializing in scuba diving activities.

Environment

The Modern Environment

Today, the average rainfall received by the Eastern Desert annually ranges between 2.75 and >50mm annually (Monein 2005, p.417).  The higher figure is recorded only in the southeastern zones.  The Eastern Desert receives more rainfall than the Western Desert, which is due largely to the relief of the Eastern Desert , where the Red Sea hills attract orographic rainfall (Davis 1953, p.158).  However, at Quesir on the Red Sea coast where the mean temperature is 28 degrees centigrade, annual rainfall is only around 4mm (Moeyersons et al 1996), whilst at Hurghada on the Red Sea coast it is nearer to 3mm (Hobbs 1989, p.4).   Occasional rainfall often takes the form of short and quite violent storms which result in large volumes of water racing down the wadis from the Red Sea mountains to the Nile or to the Red Sea.  In 1954 a freak storm caused the dry Wadi Qena to fill, and the resulting flooding caused damage in the town of Qena at its Nile end (Hobbs 1989, p.4).  Monein (2005, p.417) observes that “even though the amount of rainfall is quite small, floods are the major natural hazard in the Eastern Desert” and that  in the last 50 years flash floods have been recorded in the years 1969, 1980, 1984, 1985 and 1994.  Harrell et al (2000 p.35) record that the area of manzal el-seyl, where the Early Dynastic Gebel Manal el-Seyl stone quarry is located, translates to ‘the place where the flash floods (seyl) divide (manzal) and that this “apparently alludes to the tendency of flood waters from Wadi Mellaha Umm Barmil to split and flow around the ridge.”

Maximum and minimum recorded temperatures “are 41 degrees C and 21 degrees C respectively and increase from north to south, while the relative humidity (RH) ranges between 56% and 30%, averaging about 43% in summer and 48% in winter” (Monein 2005, p.417).

There are very few springs or wells today and these are “barely enough to supply scattered populations” (Monein 2005, p.417).  The modern towns along the Red Sea Coast, which are becoming increasingly important for tourism and are growing at a staggering rate, receive their water from the Nile through canals and pipelines or from sea water processed through desalinization plants (Monein 2005, p.417). Groundwater accounts for very little of the water consumed by human populations in and on the edges of the Eastern Desert.

Goodman and Hobbs (1988) describe the vegetation of the Egyptian desert as follows:  “Vast portions of the region are devoid of any plant cover, particularly in the north.  The higher plant concentrations tend to be in wadi bottoms, on shaded mountain slopes, and in deep canyons.  As one moves from north to south there is a notable increase in both the quantity and spacial distribution, and regularity of precipitation (p.76).  They say that most of the Eastern Desert plants belong to the Saharao-Sindian phytogeographical region (p.76).

In the desert itself, patchy and unpredictable rainfall forms temporary pools and watercourses, and the land briefly comes to life with vegetation:  “This phenomenon of brief, localized rainfall, followed by profuse but spotty and short-lived plant growth, provides the basis for Bedouin life.  Some of the water is absorbed into the ground and becomes groundwater, into which wells have been sunk since the Pharaonic period, some of which are still in use.  The modern Bedouin rely mainly on rainfall for their survival, with few wells and fewer springs.  Drip-water pools from cliff run-off is very highly regarded but uncommon.  Rain-fed rock basins are important, and my last weeks or even years, but are used sparingly to preserve an important resource (Hobbs 1989, p.47-48).  

Winters are mild and dry but may be cold at night, whilst summers are very hot and arid.  At certain times of the year frost and snow may occur when clouds hang over the mountains (Hobbs 1989, p.2)

Peter Cherry’s overview of the fauna of the Eastern Desert (2002a p.187-191) details those wild animals which survive today, in spite of the aridity.  They include feral camels, cape hare, Dorcas gazelle, lizard, Nubian ibex and a number of birds.  The birds include brown necked raven, houbara bustard (Chlamydotis undulata) and partridge (Ammoperdix heyi), spotted sand grouse (Pterocles senegallus), coronetted sandgrouse (Pterocles coronatus) desert lark, white crowned black wheatear and, although very rare indeed, ostrich (Hobbs 1989, p.91; Cherry 2002a, p.187-191).  Rock hyrax (Procavia capensis) is also present and is considered very important to the Ma’aza Bedouin (Hobbs 1989 p.88). Less popular are snakes, spiders and scorpions, all of which can bite or sting (Hobbs 1989, p.62).

Ostriches in Egypt were the subject of a paper by Nicolas Manilus (2002, p.945-953), who plots the presence of the ostrich in Egypt throughout both prehistoric and historic periods.  He concludes that the ostrich, which declined consistently since its abundant presence in the past “disappeared from the north of the country and lived only in the southeast up to the end of the nineteenth century” (Manilus 2002, p.945).  A brief revival in its fortunes between the 1960s and the early 1990s was probably the result of escapees from ostrich farms.

Due to the albeit occasional rainfall, “The Eastern Desert has a much richer flora than the Western Desert, due to its greater relief, heavier rainfall, and the larger variety of suitable habitats.  The richest communities are those of the first terrace in deep limestone valleys, and those of hills covered with flinty gravel imbedded in a sandy matrix.  Most of the desert associations must be classed as edaphic or biotic climax communities” (Davis 1953, p.172). Hobbs’s overview of the plant life that survives the arid conditions of the Ma’aza Bedouin territory include desert-adapted perennial shrubs and small trees including Acacias, Zizyphus spina-Christi, Tamarix, Solenostemma arghel, Hyoscyamus boveanus, wormwood, Ben-tree (Moringa peregrina) and Salvadora persica.  (Hobbs 1989, p.40, p.97).  Wormwood is widespread in both limestone and granite regions of the Eastern Desert, Ben tree grows only on lower flanks of high mountains which catch sufficient moisture to feed the tree, argel is quite rare.  Other vegetation springs into life when rainfall saturates the desert wadi floors, providing areas where small plots can be cultivated and herds can be pastured.  Modern occupants of the Red Sea Mountains and the desert areas include the Bedouins, of whom there are around 1000, approximately one person per 50 square miles or 90 kilometers (Hobbs 1989, p.2).  The Bedouins are made up of a number of different groups, and are not confined to Egypt, Nubia and Sinai. The Ma’aza Bedouin grow barley, millet, maize, melons and other crops in plots which are supplied with water once a year by storm floodwaters which flows down the wadis dissecting the Red Sea hills (Hobbs 1989). In modern times, the environment has been considerably modified by human intervention.  As well as the addition of formal roads where vehicles can travel, native Bedouin have removed acacia and tamarix and over-hunted barbary sheep to the point of local extinction.  Game hunters have also helped to deplete the population of gazelle. Larger wild animals are now rare.  The rainfalls are unpredictable in terms of where they will fall and how much water will be deposited, so nomads of the desert have to be mobile and flexible in their approach to division of labour, and co-operative use of tribal territories (Hobbs 1989). 

In a comparison of plant use by the Beja Bishcharin and Ma’aza Kushmaan nomads of the Eastern Desert, Goodman and Hobbs (1988) found that 21 species were used by the clans, for nutritional, medicinal and utilitarian purposes.  All 12 species used for food were common to both the Bishcharin and Kushmaan, and there are very close parallels with uses of plants for medicinal and utilitarian purposes.  Few plants were used in different or opposing ways (1988, p.86).  Interestingly, Goodman and Hobbs conclude that the data analyzed suggests that the utilization of the plants by the two groups was independently developed.  Although the groups may have had contact, they are culturally very distinct (the Bisharin of Hamitic origin, the Kushmaan from northern Arabia) and there are few indications from language or tradition of much overlap between the two. 

Today’s northern limit of Afrotropical vegetation is at Gebel Elba in the Bischarin territory (Goodman and Hobbs 1988).

In an analysis of the northern Eastern Desert’s ecological makeup Dargie and El Demerdash (1991, p.9) indicate that disturbance (grazing and woodfuel collection) and moisture status have had a considerable impact on the local environment, with water availability being heavily influenced by wadi materials and both are probably more accountable for biomass and species differences in some regions than the distinction between limestone and sandstone rock types alone proposed by some earlier writers.  Disturbance has had particularly high impact where major areas of settlement and new roads provide access to resources.

Prehistoric and Historic Periods

Gerald Fuchs has highlighted the lack of work that has been done on determining past environment in the Eastern Desert, when compared with work that has been carried out in the Western Desert: “Scientific research in the region of the Eastern Desert (Palaeobotany, Archaeozoology, Geomorphology etc) is still missing completely” (1991, p.70).  Things have improved only slightly in the intervening years.  Work done in the last 10 years or so by the Belgian Middle Egypt Prehistoric Project have helped to elucidate environmental conditions at a number of sites in the Eastern Desert/Red Sea area, but the low levels of survey and excavation in the Eastern Desert (other than rock art research), have left the environmental situation of past times somewhat unclear (Majer 1992).

The work by Moeyersons et al (2002) at the Sodmein Cave in the Red Sea Mountains, 35-40km to the NNW of Quseir, has provided some data about environmental/ecological conditions in this area at different times. However, an important lesson from studies into climate and environment across the Sahara has been that although general regional sequences may be identified, local conditions may vary enormously according to different topographical and ecological conditions: “it cannot be assumed that fluctuations in neighbouring areas were necessarily contemporaneous (Phillipson 2005, p.173).  The Sodmein Cave is in a wadi of the Red Sea Mountains, where there is greater rainfall than, for example, the plateaus of the Eastern Desert proper.  A number of periods of climatic dry and humid phases have been identified, some of which have been tied into the archaeological data from the cave.  This information is captured in the following table, compiled from data presented by Moeyersons et al (2002).  The terms humid and wet used in the table below “point to the relative idea of wetter conditions than the present-day hyperarid ones” (Moeyersons 2002, p.849) and do not necessarily indicate wet periods as we understand them.  The fact that some wet periods identified in other areas like the Western Desert are not represented here (for example a wet phase in the Eastern Sahara at 90,000 BP) may mean either that the data from Sodmein represents a localized environment not typical of the entire region, or it may imply that data is missing.  It is also possible that the data captured here represents bigger and more obvious environmental occurrences, whilst not isolating fluctuations within overall trends.
 

Date

Climate

Environmental Data

Archaeological Data

125-130,000BP

Warmer more humid phase, coinciding with the Eemian Interglacial

It is suggested that a precipitation of c.600mm per year (wet conditions) would be conceivable in the Sodmein area (p.847)

 

115,000 BP

Istotopic Stage 5e.

Rainstorms resulted in permanent pools and swamps, and other water bodies, indicated by the presence of crocodile, Clarias and Melanoides tuberculata.  Moeyersons et al also suggest that the area may have been linked to the Nile on an intermittent basis (p.849-50)

Plants include Acacia, clematis, grasses, and Ficus Sp. (Moraceae)

Big savannah fauna include bovids, kudu, elephantid and flies (Chrondmidae)

Sodmein Cave’s J-Complex (Middle Palaeolithic).  Apparently corresponds to the same wet period at Bir Tarfawi in the EAstern Desert.

Unknown, but between 115k and 25k BP

Wet periods

 

Middle Palaeolithic Level 4 C14 dated to older than 45000 BP

Middle Palaeolithic Level 2 at 29,950+/-900 and 30>/- 30,000BP

25,000 BP
(25,200+/-500)

Wetter conditions at or around this time, corresponding with a wetter period elsewhere in Africa including the Nile Valley (Paulissen and Vermeersch 1987)

 

Upper Palaeolithic Level 2, and perhaps Level 1 (Van Peer et al 1996).

Unknown, but betweeen 25000bp and c.8000bp

 

This can be represented by layers D, F. G and I at Sodmein.

A mixture of species indicate desert or semi-arid and dry sparsely wooded savannas.

Faunal remains include Capra ibex, barbary sheep, wild ass, Soemmering’s gazelle, greater kudu, vervet monkey, hunting dog, seval or caracal and leopard.

Several woods are represented in the dark (organic) layer of Layer D.

Whitish layers may be indicative of environmental degradation and drier but not hyper-arid conditions

Time gap between base of Layer C and top of Layer D coincides with LGM.

 

c.8000 – 6000 BP
(6320 – 7470 BP)

Following the LGM.  C-Layer (whitish) followed by B layer which appears to correspond to Early Holocene “wet Interglacial”.  Sparse rains are indicated, and the presence of an oasis is a possibility.  Conditions were wetter than today but without exotic elements typical of much more humid conditions elsewhere. Conditions were still somewhat arid. Conditions were apparently similar to those at Tree Shelter, 1 km away.

Ten tree species are represented, dominated by Acacia cfr Tartilis (Forsk.) Hayne and Tamarix sp.

Fauna includes present day species plu Dorcas gazelle, Rock dassie, domesticated sheep and goat, rodents and various insects including the specie Hymenoptera

Suggested an average of about two rains per “rainy season” based on C layers (p.850).

Layers C (whitish) and  B (highly organic)

Layer B is Neolithic and contains large numbers of domesticated ovicaprines associated with lithics and (top section only) ceramics

The period between 25,000 and 8000 bp in the above table lacks details.  Some idea of what sort of conditions might have been experienced in Egypt at this time are covered in an article looking at the Earlier Holocene of the Nile Valley by Vermeersch (2002, p.31).  Vermeersch suggests that the period immediately prior to 12,000 BP known as the Wild Nile phase was accompanied by a hyperarid climate. Occupation of Egypt during the Wild Nile phase is attested to at a small number of sites on the desert margins.  After the Wild Nile phase a lowering of the Nile’s floods began, perhaps becoming so low that the Faiyum lake lost access to the Nile and may have dried up for around 500 years at c.10,000 BP, and then became high between 9500 and 8000 BP – attested to at Elkab and Armant (Vermeersch 2002, p.32).  Another dry phase appears to have followed from 8000 to 7200 BP when the Faiyum dried again, but the Nile appears to have experienced high floods in Bubia at around 7200BP, when the Faiyum lake again refilled.

Dittman (1993, p.149) says that at one point during the Middle Palaeolithic samples of sinter indicated  that spring-fed open water surfaces were available at least between radiocarbon years 26,350 and 26,900 BC, but it is not clear when this humid period actually began or ended.  After the Middle Palaeolithic   “the drying-up of the region truly took the character of an ecological catastrophe:  the protective vegetation cover disappeared, the loose deposits fell victim to erosion and their deposition took place within the upper and middle sections of the drainage systems”.  Dittman summarizes the data for the later prehistory of the northern part of the Eastern Desert in Egypt as follows (1993, p.152):
 

Time

climatic Conditions

Geomorpho-Dynamic Processes

Human Culture

Recent to proto-historic

Arid

Episodical wadi floods (one event during 5-6 years)

Exrosion at the margin of lder sediments

Rock Egnravings

4000 – 2000 BC

Semi Arid

Periodical wadi floods

No important transformation processes

Neolithic occupation (hutning, stock breeding sheep and goat)

After 20,000 BP?

Arid

Episodical wadi floods

?

After 26,000 BP

Arid

Episodical wadi floods

Erosion on the slopes and accumulation of the Main Wadi Sediments int he upper and middle sections fo the wadi

?

About 26,000 BP

Semi arid tosemi humid

Longer, periodical wadi floods

Open water surfaces and development of sinter

No important geomorphic transformation processes

?

Before 26,000 BP

? (Semi Arid)

Dissecrtion of the wadi’s third section of pediment gravels

Middle Palaeolithic occupation

Toby Wilkinson, looking at the Eastern Desert as a whole, has highlighted the surprising amount of vegetation that survives today in some wadis, and suggests that “it would seem likely that a small increase in average rainfall would be sufficient to turn this semi-desert back into savannah” (p.158). 

A comparison of plant use by the Beja Bishcharin and Ma’aza Kushmaan nomads of the Eastern Desert by Goodman and Hobbs (1988) found that 21 species were used by the clans, for nutritional, medicinal and utilitarian purposes. This provides an indication of the amount of plants are available in the Eastern Desert for food (12 species), and suggests that in past times with only a slight increase in humidity, both the number of species and the density of the vegetation could have been significantly greater.

The following map, copied from Krzyzaniak 1977 (who in turn modified it from Butzer) shows the main ecological zones of the Eastern Desert between 5000 and 3000BC:
 

Butzer map02

The map implies that between 5000 and 3000 BC the Eastern Desert would have had areas which would have been very attractive for pasture, with a maximum rainfall of around 150mm.  There is one single specimen of Maerua crassifolia known from the Ma’aza’s tribal area, together with isolated examples of wild olive, white saksaul, white acacia, Indian mastiche, all of which are thought to be the last remains of the woodlands of the desert environment as it was between c.3000 and 7000BC (Hobbs 1989, p.97).

I have added the Western Desert sequence for the Neolithic below for comparative purposes, and because it has detail that shows climatic trends which were taking place in the Eastern Sahara.  It must be emphasized that local topographic conditions will have accounted for considerable variations – there is a vast difference between the rainfall conditions likely to be attracted by the highland areas of the Red Sea Hills and that by the largely un-differentiated areas of the desert zones in the Western Desert.  From Wendorf and Schild 2002:

    The Post-Al Jerar Arid Phase, c.7300-7200bp is marked by massive deflation at Napta Playa, high winds and heavy sandstorms. 

    The Middle Neolithic Humid Interphase, c.7200-6600bp showed signs of local rains but no lacustrine deposits.  Human occupation is attested to at E-75-8.  A Post Middle Neolithic Arid Phase, c.6600-6550bp is marked by deflation and aeolian erosion. 

    This is followed by the Late Neolithic Interphase, c.6550-5800bp:  “a perched water table in the deflational basin at site E-75-8 is indicated by consecutive wells in the centre” (p.24).  Another deflational stage is called the Post Late Neolithic Arid Phase and dates c.5800-5500bp. 
     

It is generally agreed that the climate of the area today was only a little more humid than during pharaonic times. The Eastern Desert began to dry out during the same period that civilization took hold in the Nile Valley.

 

Geology

As James Harrell points out in the opening comments of his paper Stone in Ancient Egypt (Harrell WR/d)  “Much of what remains of ancient Egypt consists of stone. There are building stones for temples, pyramids, and tombs; ornamental stones for vessels, sarcophagi, shrines, stelae, statues, and other sculptures; gemstones for jewelry; and utilitarian stones for tools, weapons, pigments, and other applications. Still other stones were processed to extract their precious metals. These remains range in age from the Late Predynastic period (beginning about 3200 BC) to the Roman period.”  The geology of Egypt has defined the character of its architecture and material remains.

The following text is derived, unless otherwise stated, from Bonnie Sampsell’s excellent A Travellers Guide to the Geology of Egypt (2003, p.154-183). For a full description of the geology of this (and other) areas of Egypt, I recommend her very well written book, available from the American University in Cairo Press, and various online book sellers.  An excellent online resource is James Harrell’s Eastern Desert geology site at
http://www.eeescience.utoledo.edu/Faculty/Harrell/Egypt/AGRG_Home.html

The Basement Complex was laid down from the Pre-Cambrian age. By the end of the Eocene, around 37 million years ago, the rock layers known as the Basement Complex covered Egypt.  This is made up of igneous and metamorphic rock from the Pre-Cambrian age, and Nubian sandstone from the Lower Cretaceous, Cretaceous limestones and shales and Eocene limestones.  At this time the landscape was relatively featureless in terms of geomorphology and topography (Sampsell 2003).  The plutonic igneous and metamorphic rocks which form the Red Sea mountains and hills are over 550 million years old.  Basement Complex rocks of sedimentary and volcanic igneous origins are mostly less than 100 million years old (Harrell WR-f)   The plutonic igneous and metamorphic rocks which form the Read Sea mountains and hills are over 550 million years old.  Basement complex rocks of sedimentary and volcanic igneous origins are usually less than 100 million years old (Harrell WR/f). 
 

Eon

Era

Period

Epoch

Beginning (Years ago)

Phanerozoic

Cenozoic

Quaternary

Holocene

10,000

 

 

 

Pleistocene

2 million

 

 

Tertiary

Pliocene

5.1 million

 

 

 

Miocene

24.6 million

 

 

 

Oligocene

38 million

 

 

 

Eocene

55 million

 

 

 

Paleocene

65 million

 

Mesozoic

Cretaceous

 

144 million

 

 

Jurassic

 

213 million

 

 

Triassic

 

248 million

 

Paleozoic

Permian

 

286 million

 

 

Carboinferous

 

360 million

 

 

Devonian

 

408 million

 

 

Silurian

 

438 million

 

 

Ordovician

 

505 million

 

 

Cambrian

 

590 million

Precambrian

 

 

 

c. 4600 million

Table copied from Sampsell 2003

The Pre-Cambrian rocks, some of which are exposed in the Red Sea Mountains include gabbroid, granite, serpentines, volcanic and geosynclinal metasediments and metavolcanics (Monein 2005, p.421)

Following the Eocene, it is believed that the mechanisms of plate tectonics divided the Arabian Peninsula from the African Plate, creating the Red Sea.  This process began in the Oligocene but probably continued throughout the Miocene and Pliocene.  As part of this rifting process, rock layers to the west of the Red Sea were uplifted to form the Red Sea Mountains, with similar formations developing in Saudi Arabia.  Today these mountains reach heights of nearly 3000m, but may have been much higher when formed, attracting orographic rainfall, which etched channels into the mountains and eroded rock layers, removing the vulnerable limestones and sandstones and leaving behind the more durable igneous and metamorphic rocks of the uplifted basement layer.  Today, the maximum elevation is in Gebel Shayeb el-Banat at 2187m.  Elevations are lower in the north where rock foundations are mostly of Tertiary and Mesozoic age (Ibrahim and Ibrahim 2003, p.60).

The high limestone plateaus of the Eastern Desert were formed in the Miocene and Eocene (Monein 2005, p.419).

During the Pleistocene alluvial deposits were laid down.

Today the Eocene limestone can be seen in the form of plateaus in the North of the Eastern Desert, and the basement complex rocks can be seen in the middle and southern parts of the Red Sea zone, revealed by erosion.  Red granites at the peaks of mountains provide one example.  Pleistocene alluvial deposits are distributed throughout the Eastern Desert covering wadi floors and making up alluvial fans in the Desert and forming reefs and beach deposits in the coastal belt area (Monein 2005, p.418).  South of Qena wadis draining towards the Red Sea cut through the basement complex, and some that drain into the Nile also cut through the basement complex including Wadi El-Mathula, Wadi Alaqi and Wadi Qena (Monein 2005, p.420).  In the northern part of the Eastern Desert most of the wadis cut through the sedimentary layers of the Eocene to the Quaternary, including Wadi Qassab, Wadi El-Assuti and Wadi Tarfa (Monein 2005, p.420).

The Eastern Desert is dominated by the Red Sea Mountains which extend from the latitude of Cairo down to the Egyptian-Sudanese border and beyond. Between the mountains  and the Nile valley there are broad plateaus formed of sedimentary rocks. From Cairo to north Qena these are formed of limestone and sandstone from the Cretaceous and Eocene.  To the south they are formed of Nubian sandstone.  Two enormous limestone plateaus called the Northern and Southern Galala plateaus stretch across the northern part of the Eastern Desert, with the wide Wadi Araba in between them, draining from west to east.  The Eastern Desert plateaus are dissected by wadis and ravines which run east to the Nile and west to the Red Sea.  The Basement Complex is less permeable than in the Western Desert, which has helped to form the wadis (Ibrahim and Ibrahim 2003, p.60), and the mountainous topography has obviously played a central role.  Similar topography can also be seen in highland zones of the Sahara including Egypt’s Gilf Kebir in the Western Desert.

Wadi Qena extends roughly south to north, originating at the Qena bend of the Nile, and appears to be a remnant of the Qena river system which appears to have formed and been active during the Tertiary, when it cut down through Nubian sandstone, and was a component part of an early version of the Nile.

Between the mountains and the Red Sea is a coastal plain, mostly flat, but with some topographical exceptions, including volcanic (for example Zubair and Zuqar) and coral limestone formations. 

Geologic Map of the ED

Map copied from Monein 2005, p.418

The Red Sea itself is fed today mainly by the Indian Ocean. There is only negligible rainfall and run-off available to it, and very little water is delivered by the Suez Canal.  The sea is warm, averaging c.22 degrees centigrade, and there is very high surface evaporation which has lead to it being saltier than typical sea water.  Today its maximum width is 350km, and it maximum depth, the Axial Trough, is 2000m.  It splits around Sinai to form two arms, the Gulf of Suez to the east and the Gulf of Aqaba to the west. 

During the Pliocene the Gulf of Suez was a shallow lagoon.  Today it is 80m deep.  Water levels rose and fell through time and at times were higher than they are at present.  Discoveries, for example, on former high beaches have demonstrated that sea levels were higher during the Palaeolithic and Neolithic periods. 

At the head of the Gulf of Suez is the Isthmus of Suez, the strip of land between Egypt and the Sinai Peninsula, consisting of a set of dry depressions and ridges made of sand and alluvium.

The Gulf of Aqaba to the west of the Sinai Peninsula is very deep, reaching 1700m in its central trough.  This contrast with the shallow Gulf of Suez is accounted for by the presence of a significant fault line which extended through the northern Red Sea.  The fault was caused by Arabian block in the east moving north past Sinai to the west  – it moved a distance of around 60km in the Miocene, 45 km in the Pliocene and Pleistocene and it continues to move at the rate of around 15mm per year.  The fault probably only flooded during the Pleistocene.

Sinai makes up 6% of Egypt and shares many of the geological features with the Eastern Desert, with which it formed a land mass up until the mid Tertiary.  The southern part is composed of basement complex and consists of a mixture of metamorphic and igneous rocks with more recent sedimentary rocks removed by erosion.  It was impacted by tectonic movements at various times and marked by many faults running both north to south and eat to west.  The peninsula is intersected by deep wadis.  Rainfall levels are between 50 and 100mm per year, received most in the form of storms which, as in the Eastern Desert, cause torrential flows to form in the wadis.  Some of the water is stored as groundwater, whilst the rest drains into the Gulfs of Suez and Aqaba to the east and west. 

Of the stone forms, the three broad classes are represented:  sedimentary, igneous and metamorphic.  The distribution of these rocks throughout Egypt is shown in Appendix K.

The rocks left behind by the various processes that have taken place in Egypt over millions of years have provided the raw materials for everything from Palaeolithic stone tools to the vast temple complexes of the Pharaonic periods.  Mineral deposits have, likewise, provided raw materials, some of which continue to be valued and exploited today.  Some of these resources have been available as surface finds, like jasper and cernelian (Shaw 2002, p.244) but others have required specialized knowledge to locate and extract.

The ancient Egyptians, particularly from the New Kingdom onwards, had a very good understanding of Eastern Desert geology, allowing them to exploit its resources; with experts sent to prospect for gold and other useful/valuable rocks and minerals:  “these were people who knew how to read the often subtle clues that point to valuable rock and mineral occurrences.  They did not have to climb every mountain and walk every wadi to know what was present.  They understood that the full spectrum of an area’s geologic resources can be seen in the gravel of the wadi that drains the area” (Harnell 2002, p.242). This understanding  can be illustrated by a document dating to the Nineteenth Dynasty – a Ramesside papyrus known as the Turin Map. 

The Turin papyrus shows the Wadi Hammamat with various features of geological significance highlighted, sometimes with comment in hieratic, and shows numerous geographical and geological features along a stretch of the wadi.  Amongst the geological units shown on the map are the following (taken from Harrell WR) wadi alluvium (Quaternary), Nubian sandstone (Upper Cretaceous), Fawakhir granite, Hammamat siliclastics, Dokhen volcanics and Atulla serpentinite (Late Cambrian).  Amongst the many hieratic notes made on the map are references to mountains of gold, water cistern, gold-bearing mountains, mountains of gold and sliver and bekhen stone (metagraywacke sandstone and siltstone).  For more details about the Turin Map see Harrell WR-g).

Since 1989 James Harrell and V. Max Brown (Harrell and Brown WR-a) have located 162 ancient quarries in Egypt and Sudan.  Samples were taken from 76 of the quarries for analysis using a number of different methods.  the quarries are divided into two types:  hardstone quarries which provided “rocks that were difficult to extract and carve” (Harrell and Brown WR-a). 

Egyptians have always quarried and mined the Eastern Desert for its rich supply of rocks, minerals and ores. Breccia, conglomerate, steatite, porphyry, granite, dolerite, gold, and amethyst are just a few of the natural resources available in the Eastern Desert.  See Appendix K for a list of raw materials that are found in the Eastern Desert.
 

Hydrology

In a fascinating paper entitled “Overview of the geomorphological and hydrogeological characteristics of the Eastern Desert” A.A. Adbel Moneim provides the most detailed summary of the hydrology of the Eastern Desert that I have seen to date (Moneim 2005, p.416-425).  The data for this section is taken exclusively from that paper. 

Monein says that these are very limited as resources when compared to those of the Nile Valley, the Delta, the Western Desert and Sinai:  “This is mostly due to the fact that the area is covered in most parts by crystalline rocks (mostly igneous and metamorphic), in addition to the limited sources for the recharge.  Groundwater in the Eastern Desert may be found in both shallow and deep formations.  Shallow groundwater occurs in the alluvial deposits and shallow carbonate rocks and is discharged either naturally through springs, or through drilled wells of shallow depth.  The deeper water-bearing formations, however, are more extensive and generally provide larger and more reliable well yields” (Monein 2005, p.421).

Today’s rainfall usually consists of rare and heavy downpours over a small area.  This runs as storm waters through the wadis, becomes trapped by sediments and debris, and sinks into the surface and into the ground below.  This provides groundwater which enables a certain amount of vegetation to survive, and can be accessed by deep wells of between 8m and 10m in depth. Rainfall has been discussed in more detail above in the Environment section.   

Other water sources are springs – including those at St. Paul’s and St. Anthony’s monasteries which are karstic (fissure limestone) aquifers or groundwater supplies.

Monein (2005, p.419) divides the wadi system into two main groups:

  • Drainage basins that drain toward the Red Sea Coast (the Red Sea Basin Group)
    • Catchment area covering about 42,240 km.sq.
  • Drainage basins that drain toward the Nile (the Nile Basin Group)
    • Catchment area covering about 105,580 km.sq. (10.56% of the total surface area of Egypt and about ten times the total area of the Nile Valley)
Hydrology

Copied from Monein 2005, p.419

Monein further subdivides wadis into three main classes based on their hydrologic properties (Monein 2005, 421 – and on page 420 lists the wadis that fall into these categories in both the Nile Basin and Red Sea Basin groups):

  • Class I
    • Low stream frequency
    • Low drainage density
    • High bifurcation ratio
    • Good chance of downward recharge to the shallow aquifers
  • Class II
    • High stream frequency
    • High drainage density
    • Low bifurcation ration
    • Highest flooding probability
    • Lowest groundwater potential
  • Class III
    • Intermediate drainage density
    • Intermediate drainage frequency
    • Intermediate bifurcation rations
    • Moderate groundwater potential
    • High flooding probability

There are four main water-bearing aquifers in the Eastern Desert (Moneim 2005, p.416 and p.421-424), which provide the main groundwater resources:

  • The fractured crystalline Pre-Cambrian aquifer
    • Productive only in the eastern part of the desert adjacent to the Red Sea Coast
    • Located at very shallow depth in some wadis
    • Recharged by scarce rainfall through cracks and fractures in rocks
    • Supplies some hand-dug wells used by modern desert nomads
    • The water quality is variable and may be fresh to, in the northern part of the Desert, brackish
  • The Nubian sandstone aquifer (Paleozoic-Mesozoic Clasitc aquifer)
    • The most productive
    • Lying on the Basement Complex, composed of sands and sandstone with intercalated clay and shale
    • Extends through the southern part of Egypt and beyond Egypt’s borders into Libya and Sudan to the west and Saudi Arabia to the east
    • Varies in thickness between 10 and 120m, and is thickest in the Wadi Qena
    • Varies in water depth between 4m and 40m
    • In the southeaster part of the desert there are several permanent srpings along the scarp of the Nubian sandstone – for example in the Wadi Hodien.
    • Recharge is mainly through rain
    • The main content of the aquifer is fossil water, stored during pluvial times
    • The quality of water varies from one place to another, and is quite often brackish
  • The fractured limestone and sandstone aquifers
    • Productive only in the eastern part of the desert
    • Mainly represented by the thick extensive multi-horizon succession of carbonate-rock facies, sandstones, shale and clay located in the northwestern part of the desert
    • Vary in thickness in different parts of the desert
    • Mainly recharged from occasional rainfall and stream run-off, and to a lesser degree from underlying aquifers through fractures and fissures
    • Quality of water varies from fresh to brackish
  • The Quaternary aquifer
    • Limited potential
    • Occurring along the major wadis
    • Recharged mainly from the occasional rainfall
    • Shallow groundwater supplies held in Quaternary alluvial deposits dominated by sands and gravels
    • High storage capacity
    • Quality of water is generally good
    • Not extensive and its reliability can vary both by region and by season
    • Recharge mainly by rainwater and, to a limited extent, upward leakage from the underlying deep aquifer
    • Some sea water intrusion, which may also penetrate the underlying aquifer

 

 

Copyright Andie Byrnes 2007

         
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