The Nubian Sandstone is a variety of

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

deposited on the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...

in the eastern

Sahara , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

, north-east Africa and

Arabian Peninsula The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate ...

. It consists of continental

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

with thin beds of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s, and

marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...

s. The Nubian Sandstone was deposited between the Lower

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

and Upper

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

, with marine beds dating from the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

Formation

The Nubian Sandstone ranges in age from the Cambrian to Upper Cretaceous eras. Positioning of the paleoequator and

paleolatitude Paleomagnetism (or palaeomagnetismsee ), is the study of magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rock ...

at 20° S was derived from

paleomagnetic Paleomagnetism (or palaeomagnetismsee ), is the study of magnetic fields recorded in rocks, sediment, or archeological materials. Geophysicists who specialize in paleomagnetism are called ''paleomagnetists.'' Certain magnetic minerals in rock ...

data showing the Nubian was originally deposited in the paleoequatorial to subequatorial zone. These paleomagnetic results corroborated previous studies suggesting that north Africa did not shift in latitude from 210 to 110 million years ago and extended this period to 85 million years. Nubian Sandstone was deposited under a

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

to subtropical climate and formed under a variety of continental conditions, including eolian merging intermittently into shallow marine.

Characteristics

The Nubian Sandstone complex has a thickness varying from under 500 m to over 3000 m, resting on the

. This is complicated by various structural faults and fold axes traversing the region in a north-eastern direction. Maximum development occurs in the Ain Dalla basin, a downthrown structural block south-west of the

Bahariya El-Wahat el-Bahariya or el-Bahariya ( ar, الواحات البحرية "''El-Wāḥāt El-Baḥrīya''", "the Northern Oases"); is a depression and a naturally rich oasis in the Western Desert of Egypt. It is approximately 370 km away from ...

oasis. Basement features present a dominant control on the complex's structural and sedimentological form. Despite many structural complications, the Nubian Sandstone likely constitutes a single hydrogeological system west of the

Suez Gulf The Gulf of Suez ( ar, خليج السويس, khalīǧ as-suwais; formerly , ', "Sea of Calm") is a gulf at the northern end of the Red Sea, to the west of the Sinai Peninsula. Situated to the east of the Sinai Peninsula is the smaller Gulf of ...

. To the east, on the

Sinai Peninsula The Sinai Peninsula, or simply Sinai (now usually ) (, , cop, Ⲥⲓⲛⲁ), is a peninsula in Egypt, and the only part of the country located in Asia. It is between the Mediterranean Sea to the north and the Red Sea to the south, and is a l ...

, a second system might exist with some connection to the primary western system in the north. The main western system, extending into

Libya Libya (; ar, ليبيا, Lībiyā), officially the State of Libya ( ar, دولة ليبيا, Dawlat Lībiyā), is a country in the Maghreb region in North Africa. It is bordered by the Mediterranean Sea to the north, Egypt to Egypt–Libya bo ...

and

Sudan Sudan ( or ; ar, السودان, as-Sūdān, officially the Republic of the Sudan ( ar, جمهورية السودان, link=no, Jumhūriyyat as-Sūdān), is a country in Northeast Africa. It shares borders with the Central African Republic t ...

, consists of a multi-layered

artesian Artesian may refer to: * Someone from the County of Artois * Artesian aquifer, a source of water * Artesian Builds, a former computer building company * Artesian, South Dakota, United States * Great Artesian Basin, Australia * The Artesian Hotel ...

basin where massive groundwater reserves accumulated, principally during

pluvial In geology and climatology, a pluvial is either a modern climate characterized by relatively high precipitation or an interval of time of variable length, decades to thousands of years, during which a climate is characterized by relatively high ...

s of the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...

. Locally,

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolosto ...

s overlying complex

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

features and are recharged from the underlying major

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

Fluvial In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluviog ...

and structural interpretations from 2007 show the desert in western Egypt was induced by fluvial action, including recently mapped

alluvial fans An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

. In central areas,

braided channel A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment l ...

s are spatially aligned to a north-east structural trend, suggesting preferential water flow paths. Alluvial fans and structurally enclosed channels with gentle slopes and optimal recharge conditions between 1 and 5%, indicating high groundwater potential.

Synthetic Aperture Radar Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. SAR uses the motion of the radar antenna over a target region to provide fine ...

(SAR) interpretations correlated with anomalies from groundwater in 383 wells, suggest a connection between the spatial organization of fluvial and structural features with low-

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

groundwater, which exists adjacent to alluvial fans and the south-west reaches of structurally enclosed channels. Wells in the vicinity of structures contained low-salinity water.

Derived soils

Nubian Sandstone exposures in sub-humid, semi-arid, and

arid A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...

conditions produce

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

that is red and sandy but very different in other aspects. Only in sub-humid zones do these soils contain a moderately developed profile, including a textural

B horizon A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. ...

lacking soluble salts and

carbonates A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...

. In semi-arid and arid zones, profile differentiation is either weak or does not exist. In arid zones soils are shallow and contain carbonates, and soluble salts, including

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...

. The sole

clay mineral Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals ...

common to all Nubian sandstone parent materials is

kaolinite Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...

, which is the major clay mineral in sub-humid zone soil. In semi-arid soils

smectite A smectite (from ancient Greek ''σμηκτός'' smektos 'lubricated'; ''σμηκτρίς'' smektris 'walker's earth', 'fuller's earth'; rubbing earth; earth that has the property of cleaning) is a mineral mixtures of various swelling sheet sil ...

is a second major clay component. In arid zones small amounts of smectite and

palygorskite Palygorskite or attapulgite is a magnesium aluminium phyllosilicate with the chemical formula ) that occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller's earth. Some smaller deposits of this ...

accompany kaolinite. It is likely that smectite and palygorskite are products of pedogenic neoformation. Aeolian material was probably introduced into the

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

and fine sand fractions from semi-arid and arid soils. It is also possible that some contamination of clay fractions occurred.

Nubian Sandstone in Arabia

When in contact with Upper Cretaceous

, Nubian Sandstone underlies the latter conformably. In

Lebanon Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to the north and east and Israel to the south, while Cyprus li ...

Anti-Lebanon The Anti-Lebanon Mountains ( ar, جبال لبنان الشرقية, Jibāl Lubnān ash-Sharqiyyah, Eastern Mountains of Lebanon; Lebanese Arabic: , , "Eastern Mountains") are a southwest–northeast-trending mountain range that forms most of th ...

and

Hermon Mount Hermon ( ar, جبل الشيخ or جبل حرمون / ALA-LC: ''Jabal al-Shaykh'' ("Mountain of the Sheikh") or ''Jabal Haramun''; he, הַר חֶרְמוֹן, ''Har Hermon'') is a mountain cluster constituting the southern end of the ...

it is underlain by

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

limestone. Its upper strata is likely from the Lower or Middle Cretaceous age. However, Jurassic limestone is absent in southern areas. In Western

Sinai Sinai commonly refers to: * Sinai Peninsula, Egypt * Mount Sinai, a mountain in the Sinai Peninsula, Egypt * Biblical Mount Sinai, the site in the Bible where Moses received the Law of God Sinai may also refer to: * Sinai, South Dakota, a place ...

, Nubian Sandstone rests on Carboniferous limestone, and by the

Dead Sea The Dead Sea ( he, יַם הַמֶּלַח, ''Yam hamMelaḥ''; ar, اَلْبَحْرُ الْمَيْتُ, ''Āl-Baḥrū l-Maytū''), also known by other names, is a salt lake bordered by Jordan to the east and Israel and the West Bank ...

on Cambrian limestone: at

Petra Petra ( ar, ٱلْبَتْرَاء, Al-Batrāʾ; grc, Πέτρα, "Rock", Nabataean Aramaic, Nabataean: ), originally known to its inhabitants as Raqmu or Raqēmō, is an historic and archaeological city in southern Jordan. It is adjacent to t ...

and other locations it rests unconformably on

crystalline rock A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...

s. While age calculation for the Nubian Sandstone is relatively simple in Lebanon, Anti-Lebanon and Hermon, it is much more complicated in Western Sinai and the Dead Sea area. Since sandstone is assumed to form more rapidly than other rocks it is difficult to conceive that the 2,000 feet of sandstone in the southeastern Dead Sea was in the formative process from the Cambrian to the Cretaceous.

Appearance

Nubian Sandstone is most commonly brown or reddish, but in places it shows a much wider variety of color. The ancient temples and tombs in Petra were carved from this rock. In certain places it is extremely

friable Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, ...

, and in others compact and hard. Sand in the Arabian deserts was primarily derived from it, carried by prevailing western winds. Where it is covered by a sheet of eruptive rock (''charrah''), it is protected from

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

. Nubian Sandstone frequently includes strata of clay and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

and thin seams of

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...

lignite Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low heat ...

. This indicates that it was deposited in seas that were relatively shallow at the time.

Etymology

The term ''Nubian Sandstone'' was first introduced to the Egyptian

stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...

by Joseph Rüssegger in 1837, who used the term "Sandstein von Nubien" to designate nonfossiliferous sandstone sections of Paleozoic or Mesozoic age. Rüssegger followed and studied this series of sandstone formations from the

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...

, and Arabia Petrsea (northeastern Arabia).R. Tate pp. 404-406

Notes

References

* *El Shazly, Atomic Energy Establishment, Egypt 1982 *A.A. Shata
''Hydrogeology of the Great Nubian Sandstone Basin''
Desert Research Institute, Egypt 1982 *
Essay and Maps: Groundwater Resources of the Nubian Aquifer System
*El Sayed
''A Study of Hydrogeological Conditions of the Nubian Sandstone Aguifer in the Area between Abu Simbel & Toschka, Western Desert, Egypt''
American Geophysical Union 2001 *A.C. Seward: ''Leaves of Dicotyledons from Nubian sandstone of Egypt'', Geological Survey, 1935. * *

* {{cite journal , last1=Singer , first1=A. , last2=Amiel , first2=A. J. , title=Characteristics of Nubian Sandstone-Derived Soils , journal=Journal of Soil Science , date=1974 , volume=25 , issue=3 , pages=310–319 , doi=10.1111/j.1365-2389.1974.tb01127.x

External links

Quarterly Journal of the Geological SocietyEssay and Maps: Groundwater Resources of the Nubian Aquifer System
* ttps://web.archive.org/web/20061023213115/http://www.dmmr.gov.sa/geology-ksa.php Geology of Saudi Arabia Geologic formations of Africa Geologic formations of Egypt Geologic formations of Libya Geologic formations of Asia Geology of the Middle East Sandstone formations Building stone