Egypt Civilization and Geology

EgyptCivilization and Geology

Hassan Z. Harraz [email protected]

TYPES OF ROCKS - The Rock Cycle

TheGeologic

TimeScale

EGYPTBEDROCK

BEDROCK OF EGYPT

Top LayerLimestones

Intermediate LayerSandstone

The Basement ComplexIgneous Rocks

AndMetamorphic

BEDROCK OF EGYPT

Top LayerLimestones



AndMetamorphic

BEDROCK OF EGYPT

Top LayerLimestones



AndMetamorphic

BEDROCK OF EGYPT

Top LayerLimestones



AndMetamorphic

BEDROCK OF EGYPT

Top LayerLimestones



AndMetamorphic

According to the “Rock Cycle,” New IGNEOUS ROCK can be made from:

A.) Sedimentary RockB.) Metamorphic RockC.) Older Igneous RockD.) All of the AboveE.) Only A and BF.) None of the Above –

It Only Comes from the Mantle

TheGeologic

TimeScale

Precambrian0.59 billion

(590 million)to

4.6 billionyears ago

SW (West Nile Craton)2 billion years ago

Eastern Desert and Sinai 0.5 to 1 billion years ago

TheBASEMENTCOMPLEX

The Past

THE BASEMENT COMPLEXContinuous Beneath The Entire Country

Southwest at Gebel Uweinat



Scattered southern portions of the Western Desert


Southern Portion of the Sinai




High Mountains

Eastern Desert





High Mountains

Eastern Desert


Aswan at theFirst Nile Cataract



BASEMENT COMPLEXSinai Area

Metamorphic Rocks Cutby Igneous Intrusions

Photos by: Alan Kehew

THE PRECAMBRIAN ROCKS OF EGYPTARE COMPOSED OF:

A.) Igneous RocksB.) Metamorphic RocksC.) Sedimentary RocksD.) All of the AboveE.) Only A and B

INTERMEDIATE ROCK UNITS

Paleocene – 55 to 65 million years agoShale (mud)

Late Cretaceous – 80 to 90 million years agoFine, White Limestone (often called Chalk)

Shale (mud)Nubian Sandstone

The Past

Figure 3-39A CONTINENTAL DRIFT Late PaleozoicTethys Sea

Late Paleozoic





TheGeologic

TimeScale

late Cretaceous80 million

to90 millionyears ago


Nubian Sandstone


Nubian Sandstone• medium-sized silica gains• loosely cemented with quartz and iron oxide

(ferruginous) cements and chlorite clays• highly porous and friable

easy to quarry and carve• strength – sparse

but always present due to quartz cement• iron produces yellow-red-brown color• manganese sometimes present produces

purple to black color

EGYPTBEDROCK

Nubian Sandstoneexposed in southern Egypt (1/3 of country)

and in northern Nubia (Sudan)

THE NUBIAN SANDSTONE OF EGYPT IS:

A.) Well Cemented, Very Dense and HardB.) Moderately Cemented and Reasonably

Durable due to Quartz CementC.) Poorly Cemented and NO Use

as a Building Stone D.) Only Found as Loose Sand in Wide-spread

Sand Sheets throughout the Western DesertE.) Never Exposed at the Surface

TheGeologic

TimeScale




Nubian Sandstone

Basement Complex

UNCONFORMITY(MISSING ROCK)Basement Complex Uplifted, Weathered and Eroded Away









TheGeologic

TimeScale




Fine, White Limestone(often called Chalk)overlays a layer of

Shale

Nubian Sandstone

Facies DevelopmentMarine Transgressions

and Regressions

General Model









TheGeologic

TimeScale

Paleocene55 million



Paleocene Shale(Text book refers to thisas part of the Cretaceous

Limestone and Shale Package)

Facies DevelopmentMarine Transgressions

and Regressions

General Model

EGYPTBEDROCK

Paleocene ShaleCretaceous Shale

and Limestone

UPPER ROCK UNITSPresent

• Alluvium deposited in Nile River Valley, Sand Sheets and Dunes in the Western Desert and Sinai

Pliocene 5.1 to 2 million years ago• Seas retreat - Erosion and Denudation

Miocene 24.6 to 5.1 million years ago• Limestones

Oligocene 38 to 24.6 million years ago• Regional Tectonics as Red Sea begins to open• Basalt sheet flows• Conglomerates along coast

Eocene – 38 million to 55 million years ago• Limestone





Oligocene 38 to 24.6 million years ago• Regional Tectonics as Red Sea begins to open• Basalt sheet flows

Conglomerates along coast


TheGeologic

TimeScale

Eocene38 million


UPPER ROCK UNITS

EoceneLimestone

Giza Plateau and Pyramids are composed of

Eocene Limestone

UPPER ROCK UNITSEocene – 38 million to 55 million years ago

Limestone• thickness varies due to deposition on folded

substrate (north-south compression at end of Cretaceous Period)• composition varies due to deposition during

transgression of Tethys Sea• various members (sub-layers) can be distinguished• units become thicker basinward toward the north

due to that portion always being covered by the transgressing Tethys Sea

• units dip gently to the north due to post-depositional tectonic uplift

EGYPTBEDROCK

Eocene Limestone exposed in central Egypt north to Cairo

LIMESTONE WOULD BE EXPECTED TO OCCUR ______________ THE ROCK

SEQUENCE DUE TO A TRANSGRESSIVE EVENT (RISE IN SEA LEVEL)

A.) at the Top ofB.) at the Bottom ofC.) at the Middle ofD.) ThroughoutE.) Nowhere in







TheGeologic

TimeScale

Oligocene38 to 24.6 million

years ago

UPPER ROCK UNITS

• Regional Tectonics as Red Sea begins to open• Basalt sheet flows in SW near Gebel Uweinat, Gilf Kebir, north of Fayum to NE of Cairo• Tethys Sea coast-latitude of

Fayum Depression & Cairo

• Conglomerates with land animal fossils and large tree trunks deposited in streams along coast

EGYPTBEDROCK

Basalt sheet flows in SW near Gebel Uweinat

EGYPTBEDROCK

Basalt sheet flows near Gilf Kebir


EGYPTBEDROCK

Basalt sheet flows near Gilf Kebir


Basalt sheet flows north of Fayum to

NE of Cairo

EGYPTBEDROCK

Tethys Sea coast at latitude of Fayum

Depression & Cairo

Conglomerates with land animal fossils

and large tree trunks deposited in streams

along coast






Eocene – 38 million to 55 million years ago

• Limestone

TheGeologic

TimeScale

Miocene24.6 to 5.1 million

years ago

UPPER ROCK UNITS

Limestones deposited south of modern Mediterranean Sea coast and Gulf of Suez coast (early-mid Miocene)

EGYPTBEDROCK

Limestones deposited south of modern Mediterranean Sea coast and Gulf of

Suez coast (early-mid Miocene)







• Limestone

TRUE or FLASE

Extensive, area-wide erosion took place during the Pliocene due to a regression (relative drop in

sea level or tectonic rise in land elevation)

TheGeologic

TimeScale

Pliocene5.1 to 2 million

years ago

UPPER ROCK UNITS

• Seas retreatedprobably land uplifted

• Erosion and denudation variable throughout Egypt

• Bedrock exposed as erosion proceeded







• Limestone

TheGeologic

TimeScale

Present

UPPER ROCK UNITS

Alluvium deposited in Nile River Valley, Sand Sheets and Dunes in the Western

Desert and Sinai

EGYPTBEDROCK

Alluvium deposited in Nile River Valley

Sand Sheets and Dunes deposited in the Western

Desert

Sand Sheets and Dunes

deposited in the Sinai

Delta Growth

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Egypt Civilization and Geology