Eastern Desert

The Eastern Desert (known archaically as Arabia or the Arabian Desert) is the part of the Sahara Desert that is located east of the Nile River. It spans 223,000 square kilometres (86,000 sq mi) of northeastern Africa and is bordered by the Gulf of Suez and the Red Sea to the east, and the Nile River to the west. It extends through Egypt, Eritrea, Ethiopia, and the Sudan. The Eastern Desert consists of a mountain range which runs parallel to the coast (known as the Red Sea Hills), wide sedimentary plateaus extending from either side of the mountains and the Red Sea coast. The rainfall, climate, vegetation and animal life sustained in the desert varies between these different regions. The Eastern Desert has been a mining site for building materials, as well as precious and semi-precious metals, throughout history. It has historically contained many trade routes leading to and from the Red Sea, including the Suez Canal.
Between 100 and 35 million years ago the area that is now the Eastern Desert was underwater, covered by the Tethys Ocean. During the Oligocene period, around 34 million years ago, the land began to tilt and the coastline was pushed back to the north and west. Concurrently, the basement complex to the east was uplifted, forming the mountain range of the Desert. In this same sequence of land movements, a rift which is now the Red Sea was opened up.
The mountain range of the Eastern Desert runs between 80 and 137 kilometres (50 and 85 mi) inland from and parallel to the Red Sea Coast. It has peaks around 1,500 metres (4,900 ft) above sea level. The southern mountains are predominantly composed of igneous rock while the mountains to the north are composed of limestone. Separating the mountains are wide wadis which allow for the runoff of rainfall from the mountains to the Red Sea and the Nile River. The mountain range's highest peak is Gebel Shayeb EI-Banat at 2,184 metres (7,165 ft) above sea level. Other significant peaks include Jebel Erba (2,217 metres (7,274 ft)) Jabal Oda (2,160 metres (7,090 ft)), Jabal Shaib al Banat (2,087 metres (6,847 ft)), Jebel Hamata (1,961 metres (6,434 ft)), Gebel Amm Anad (1,782 metres (5,846 ft)), South Galala (1,464 metres (4,803 ft)), and North Galala (1,274 metres (4,180 ft)).
Sedimentary plateaus run on either side of the mountains. In general, the northern sections of these plateaus have a limestone base while the southern sections are sandstone. The plateau between the Nile River and the mountains is also known as the inland Eastern Desert and is subdivided into four sections: The Cairo-Suez Desert, The Limestone Desert, The Sandstone (Idfu-Kom Ombo) Desert, and the Nubian Desert.
The Red Sea coastland is the easternmost part of the Eastern Desert, running between Eritrea and the Gulf of Suez. The distance between the coastline and the base of the mountain range varies between 30 and 175 kilometres (19 and 109 mi).
The Eastern Desert has a semi-arid/arid/hyper-arid climate. On average, the region usually receives less than 25 millimetres (0.98 in) of rainfall per year in infrequent patterns. Most of the rainfall occurs during the winter months around the mountains. The presence of the mountains can create a rain shadow for the rest of the Desert, contributing to the arid environment.
Average temperatures are between 14 and 21 °C (57 and 70 °F) in winter (November–March) and 23.1 and 23.1 °C (73.6 and 73.6 °F) in summer (May–September). The weather is typically sunny; however, sandstorms can occur, usually between March and June. The storms (khamsins) are caused by tropical air moving up from Sudan, accompanied by strong winds and higher temperatures. The term khamsin comes from the Arabic word meaning fifty, as the storms occur on an average of fifty days per year.
Carbon dating of samples of fossil tufas, a type of limestone which is deposited in the presence of high groundwater levels, has revealed that there have historically been two periods when the Eastern Desert was significantly wetter than it is today. These occurred in the late Pleistocene age, around 100,000 years ago, and the mid Holocene age, around 6,000 years ago. The most recent wet period is known to have been a result of summer monsoonal rains that moved over the Desert from the Indian Ocean. During these times, some areas of the land were swamp. The mountains and desert plateaus were also able to sustain more vegetation and animals. In between these periods the desert climate has remained mostly arid, as it is today.
The vegetation growing in the Eastern Desert is classified as either ephemeral or perennial. Ephemeral vegetation are plants which usually have a single season lifespan due to their dependence on rain. Perennial plants live for two or more years.
There are three main ecosystems within the coastal region of the Eastern Desert: littoral salt marsh, coastal desert and coastal mountains. The presence of sea spray, tidal movements and salt water seepage means that vegetation in these areas must be well adapted to living in a saline environment.
The salt marsh is created as mud builds up on tidal flats and plants grow on the mud, making it a more stable and permanent ecosystem. The two main types of vegetation in this area are mangrove and salt marsh vegetation.
Avicennia marina, or grey mangrove is the dominant mangrove plant in the Red Sea area. It grows consistently along a large stretch of the Red Sea coast but is rarely seen to the North of the Egyptian city, Hurghada. Rhizophora mucronata, or loop-root mangrove, also grows co-dominantly with A.Marina in some areas along the coast but it is less prevalent. The loop-root mangrove is taller than the grey mangrove and thus, in areas where they do grow together, they form a two-tiered canopy of leaves. Small plants such as Cymodocea ciliata and Halophila oualis typically form the undergrowth of the mangrove community.
The salt marsh vegetation is made up of a mix of shrub, succulent and grass species. The growth of these plants often creates the coastal dunes as the root systems hold the sand in place when other areas are left exposed to wind erosion.
Shrub communities
Succulent communities
Grass communities
Coastal desert vegetation grown in the band between the littoral salt marsh and the base of the coastal mountains. In comparison to the littoral salt marsh area, the soil is non-saline and arid. The growing vegetation relies on the drainage of water from the mountains via wadis. As a result, growth of plants is seasonal, unlike in the littoral salt marsh. A greater variety of vegetation also grows in the area compared to the salt marsh area. The ephemeral vegetation includes a mix of grasses, succulents and herbaceous plants. Perennial vegetation is made up of succulents, grasses and woody shrub species.
The vegetation cover on the coastal mountains is more dense than on the coastal desert. There are over 400 plant species within the coastal mountains eco-system, including shrubs, herbs and ferns. The distribution of these species varies subtly as the altitude changes.
The plants which grow on the inland plateaus vary greatly in their distribution and species due to the difference in sandstone and limestone rock bases and the varying amount of rain and runoff water from the wadis.
The wildlife of the Eastern Desert is quite different from that of the Western Desert, as the presence of the Nile River and the Red Sea Mountains provide variable eco-regions. Small mammals such as the fennec fox, golden spiny mouse, bushy-tailed jird, jerboa and other rodents live in the on the plateaus of the Desert. Other larger mammals include the hyrax, Egyptian mongoose and the Egyptian wolf. The Red Sea Hills provide a unique mountainous habitat which increases the diversity of fauna in the Eastern Desert. Species found in the mountains include the aoudad, a mountain dwelling species of sheep, the Nubian ibex and the Dorcus gazelle. The mountain range also provides a habitat for a variety of birdlife including the golden eagle and the bearded vulture, which are rarely found in any other areas of the Sahara. The Nile Valley is a central location for bird migration and there are more than 200 species of birds which pass through the western side of the Eastern desert during the migration seasons.
The mining of precious metals dates back to Ancient Egyptian times and has carried on in the Eastern Desert until present day. From the early Pharaonic era (3000 BC), copper and gold were mined from the Desert and used to make tools and for jewellery and embellishment. It was not until much later, around 1000 BC, that iron was also discovered and began to be mined. Wadis were used as routes to cart the mined materials back to the civilisation. There were also mines for precious rocks such as emeralds and amethysts that were discovered by the Ancient Egyptians, and used during the Roman and Islamic periods. As well as precious materials, valuable building and sculpting materials have also been mined from the Eastern desert such as limestone, granite and marble. Today, most of the mining that occurs in and around the Eastern Desert is for crude oil and natural gas.
The earliest signs of humans in the desert was found in the form of flint tools from 250,000 BC.
Around 25,000 BC, the land underwent significant climatic change which transformed the grassy plains into desert. This made the land much less habitable and, as a result of this change, nomads which had inhabited the land that is now the Eastern Desert were driven towards the Nile River.
Trade routes from the Nile to the Red sea were established through the Desert. Notably, there was a route between the Nile River and Mersa Gawasis, an Ancient Egyptian port. There were also many mines and quarries along this route. Boats were carried in pieces across the desert through the wadis and then set up once they reached the port to embark on expeditions. The Ancient Egyptians exploited the desert resources of copper, gold, iron and precious stones. As well as for trade, they used these resources to improve their society and in their burials.
Commercial trade increased further during the Roman period (30 BC–AD 395) and more trade routes were established across the desert. Red Sea ports were points of embarkation for trade with India. During the Ptolemaic and Roman period the chief port was Berenice Troglodytica, and the Via Hadriana led from Berenice to Antinoöpolis on the Nile. Items being traded diversified during this period to include goods such as fabrics and pearls. "Imperial Porphyry" was quarried at Mons Claudianus into the Byzantine era. The Romans set up multiple ports along the red sea coast to transport materials. Roman soldiers lived and worked at these ports. Their main sources of food were pigs, donkeys and camels.
The Eastern Desert is a popular site for tours, safaris and other expeditions. Mining also still occurs in the Desert.