Geology of EgyptBy Prof.Dr.F.A.El-Nozahy

Alexandria University

Faculty of science

Geology Department

Location

• Egypt forms the northeastern corner of Africa

• It lies between longitudes:25and37E.,and latitudes:22and32N.

• It bounded by Mediterranean sea to the north, red sea to the east, Sudan to the south and LIBYA

Area

• 1milion Square Kilometers (it covers about(1/30)of the continent Africa.

• Length 1037km.

• width about 1226km.

Climate

1.Type of belt: A part of the great desert belt.

2.Temperature:T ranges from 50ْc in daytime in summer to few degrees above 0ْC at night in winter

3.Rainfall: The average rate of rainfall 1cm/s, the rate of rainfall about 20 cm/s at coast

Humidity

• The northern coast is damper in summer than in winter,

• In upper Egypt the weather became warmer while the humidity diminishes.

Wind

• Generally the Egyptian province shows two distinct climatic zones:

Zone

Geomorphology

• Eygpt is geographically divided into four main different regions, each having its own pecular features:

Cultivated land

• Covering an area of about 35,000km2 (3.5 % of the Egyptian surface ).

• the cultivated land are covered by mantel of transported loose material (the present bed of the river). the lower part of this mantel is made of unknown thickness of irregular under-ground water bearing layer of sand and gravels

1. The Egyptian part of the Nile

• the Nile enters Egypt at W. halfa it passes for more than 300km through a narrow valley surrounded by cliffs of sandstone and granites on both eastern and western sides until it reach the first cataract which commences about7km south Aswan.

• At Gezira ( N. Aswan ) granites pass beneath.• the average width of the flat alluvial floor of the

Nile valley between and Cairo is about10km. and the river itself about 3/4km.

• the cultivated lands on the west of the river are generally much wider than those on the east.

1- The Delta

-Area is about 22,000km2(2.2%)

-It lies about 20km NW

of Cairo where the Nile valley opens into a triangular alluvial fan.

-only about half of the

delta is cultivated.

1- The Delta

Area is about 22,000km2or form 2.2%of the Egyptian surface. it lies about 20km NW of Cairo where the Nile valley opens into a triangular alluvial fan. only about half of the delta is cultivated.

The Fayoum

• A wide deep depression at the NE rim of the western desert, distant about 60 km S of Cairo.

• F.D is connected to the Nile valley by a narrow opening near Beni-suef through, which runs Bahr Youssef carrying Nile water and alluvium.

• To the NW of the depression lies Birket Qarun(45km below sea level) over an area of about200km.

• F.D is bounded from north by cliff of Eocene rock.

II.WESTREN DESERT

• Covering an area of about 681,000km2(68.1%of the Egyptian surface).It is one of most arid region in the globe.

• W.D is a typical plateau desert composed of a number of wide flat bre desolate noninhabitable rocky plateau,with great-enclosed oasis and depression.

• The great,extensive desert plateau include three plateaus:

II.WESTREN DESERT

southern sandstone

plateau

Middle limestone plateau

Northern miocene plateau

Southern sandstone plateau

Rises about 1000 ms,above S.L,this

vst s.s plateau extend more than 200km to the NE of g.oweint,the ground slopes gradually towrd depression or oasis kurkur,Dungel,Baris,kharga and Dakhla.

Middle limestone plateau

• Rises about 500ms. composed of Cretceous argillaceous rocks and limestone overlain by lower Eocene and chalky L.s.

• In this L.s plateau lies Farafra and Bahariya oases.

Northern Miocene plateau

Elevation reaches to 200ms. and gradually slopping toward the med.coast.it bounded from sounded from south by Siwa and Moghra escrpment. It extends along med.coast between Alex. and Salum.This plateau made mostly of fossiliferous marine Miocene L.s.

Origin of the depression (Oases)

Three main opinions are suggested on the mode of formation of these depressions:

1. subarial denudation and weathering(beadnell,1901;hume,1925;sandford and arkel,1929)

2. tectonic action(knetsch and yallowze,1955)

3. combination action of tectonic deformation and weathering(ibrahim,1952;said,1962)

Remarkable features of the western desert

1. Absence of well defined wades due to the arid nature of the desert. most of the desert are noninhabitable due to scanty of water. few wades drain from Estern edge into the Nile valley, few others drain into the med.sea.

2. Artesian wells are situated in the oases,where under ground water re confined to the Nb.s.s formations observed at or near G Oweinat.

3. Abundance of sand dune belts running in NW-SE direction(direction of prevailing wind)e.g. Abu Maharik dune and great sand dunes, the first one extends500-700km.

4. The presence of enclosed oases and depression bounded by steep rocky walls those are namely Bahariya,Farafra,kharga,Dakhla,dungel and kurkur in addition to Qattara,wadi El-natrun and wade El-rayan depression

5. w.d have anticline structure with axis trend NE-SW (in the northern portion).

6. WD have pronounced parallel ridges in N.part parallel to Mediterranean coast.

iii. Eastern desert

* covering an area of about 223.000km2(22.3%of the Egyptian surface).

* extends eastward from the Nile valley to the red sea

* composed of backbone of the true mountain ranges flanked by sed.plateau

* The mountain series dissected by steep ravines and dry valleys which drain either to the Nile or to the Red sea.

Eastern Desert province is divided longitudinally into:1. Crystalline mountain ranges:Mountains are mostly of igneous and metamorphic.The Red sea mountainous series are series of closely

aligned mountains pii to the coastthe highest top is G.El-shayib(2184ms.).2. Extensive sedimentary plateauFlanking the igneous backbone from West, North, South.the sedimentary plateau includes two parts;

The first extends from south to the north at wade Qena, called. s.s pl. composed of Nb.s.s

The second extends from Qena to the north of desert, composed of limestone and called El-Maaza p . Elevation over 500ms height.

Eastern desert province is divided longitudinally into:

• The northern portion of the E. desert is composed of extensive high limestone plateau of M. Eocene include s. galala,n. galala and G. Ataqa.

• Separated by long and wide valley that drain to the gulf of suez named w.araba along the Cairo-Suez road, Miocene and Oligocene strata outcrop in low hillocks tectonic effects are manifested by several faults and basalt extrusion

Eastern Desert province is divided longitudinally into:

Contrast between western and eastern desert

feature western desert eastern desert

Nature plateau nature Mountaneous

wadisrare wide and directed to med northerly and to the nile in east.

numerous wadis directed to red sea and to the nile.

Oasis present examples,...,...,... absent

Sand dunes present examples,...,...,... absent

Water under ground water surfecial water

iv.Sinai peninsula

iv.Sinai peninsula

• Triangular in shape, covering an are of about 61.000km2

or 6% of the egyptian surface.• The base stretching along the Mediterranean coast from

port said to Rafh, the Apex ending by Ras Mohammed between the two gulfs of Suez and Aqaba.

• The southern part my be regarded s the prolongation of the red sea backbone of the estern desert.

• The Northern portion is geologically similar to the neighboring asiatic region.

• Sinai peninsula is divided topographically into three main geomorphologic units:

1. Southern mountain massif

• Consists of igneous and metamorphic complex,the highest peak is g.khathrin(2641ms).

• Dissected by deep gorges draining to the gulf of Suez or Akaba.

• Northward it covers by Nb.s.s and to the west by carboniferous deposits.

1. Southern mountain massif

2. Central plateau

• A vast plateau of cretaceous chalk and Eocene l.s. composed of southern Egma plateau and El-Tih plateau(1620ms.)decreasing in height to the North.

• This plateau is dissected by wades either to the Mediterranean (W. El-Arish) or to the Gulfs (wades Sudr&Raha )

3. Northern heights

• Represented by some parallel domal or anticline mountain ranges as a result of folding with NE-SW axes.

4. Northern sand dunes

• The northern portion of sinai is covered by vast sea of sand. sands are loose,soft,they largely absorb the surface water and store them as a source to many wells found in the depressions between the dunes.

iv.Sinai peninsula

Red sea islands and coral coral reefs

• Red sea hve a numerous scattered islands near its coastal areas which, devoid of vegetation ,natural water resources and uninhabitable ,examples as sant jones, wade el gemal,gefatin , shedwan , jubal island... ...ect.

• Few of them are composed mainly of igneous rocks which oppose navigation as in brothers island.

The Mediterranean sea

• Considered by geographers as a narrow gulf extending from the atlantic ocean to separate south europe from n.africa.

• This sea is the remnant of an old vast sea (tethys) which one covered north africa south europe and west asia especially during the mesozoic era.

• The invasion of the m. sea was repeated on the egyptian land as seen in the raised beaches along the coast.

• Along the med. sea there are a number of shallow lakes and marshes(edko,borrollus,manzalla and bardawill). these lakes are relics of the ancient sea areas and isolated by precipitation and sedimentation action during pliestocene and recent ages.

• Salinity about 38 gr./l normal temp. turbid due to muddy deposits provided by nile water

The red sea

• Consider as a part of the north east african graben,its elongation has nw-se direction.

• Greece gave name erythres sea (eros) to red sea while arab named it clysm sea red sea include three zones;coastal area,transitional area,and deep marine area.

• The red sea is much younger in formation than the med. Sea. The great african graben initiated as a result of tertiary tectonic movements. The net result of these tectonic movements is the invasion of indian ocean in the from of inland sea or tongue to separate asia from africa.

• Salinity about 45 gr/l, high temperature and absence of muddy sediments provide a favorable condition for the developments of coral reefs. Average depth about 1380.Ms.

Name red sea

• in greek:erthres.s• inarabic:clysmic.s• according to water depth• three are three zones p11• to the mojor 8 xis• 0-50 ms:coastol area• (corolline area)• 50-1100ms :transionol area• 1100-2000ms :deep area