Roche du Bénin

ABOMEY CALAVIE UNIVERSITE

ADJARRA UNIVERSITARY CENTRE

GEOGRAPHY AND TERRITORY DEPARTMENT

Exposed

Directed by members of Group No.23

Sous la supervision du

Dr Corneille TEBA

YEAR ACADEMIQUE

2019-2020 

LES MEMBRES DU GROUPE

1. ABATAN Mauricette

2. AHOUNOU Anicette

3. AMOUSSOU Lucien

4. ASSOGBA Loïc

5. ASSOGBA Zita

6. FOHOUNHEDO Marius

7. GBENOU Adrien

8. GBETINSANON Pacôme

9. GBODOGBE Jean-Marie

10. GBODOGBE Marius

11. GNAMBODE Clément

12. HOUNGA Jacques

13. HOUNGAVOU Armand

14. HOUNKOKOE Ugues

15. HOUNYEME Martine

16. HOUNZEHOUE Armel

17. KOUGBLENOU Idelphonse

18. KOULIHO Alexandre

19. LAWSON Donatien

20. MONOU Jacques

21. OGOUDJOBI Ghislain

22. SOUWIN Benoît

23. TOGBE Igor

24. TOVIHO Gildas

Plan

Introduction

I-Structure of rocks

A-Definition of a Rock

B- Minerals

C- The classification of rocks

a-the magmatic rocks

b-the metamorphic rocks

c- sedimentary rocks

II- Magmatic rocks

a-The formation of plutonic rocks

b-the different types of plutonic rocks

granite

III- Metamorphic rocks

a-The formation of metamorphic rocks

b-the different types of metamorphic rocks

IV- Sedimentary rocks

sedimentary rock formation

a sandstone

b-the clay

c-the limestone

d-the gypse

e-the coal

f-oil

Conclusion

Introduction

The rock, from the popular Latin rocca, refers to any material that constitutes the earth's crust. Any material that enters the composition of the subsoil is formed by an assemblage of minerals, sometimes consisting of fossils, and/or aggregates of other rocks. There are several types of rocks in the world; this is also the case in Benin.

I/Structure of rocks

A- Definition of a rock

Any material that makes up the earth's crust is called rock, the materials that make up the rocks are classified as mineral materials in contrast to the organic materials that make up living things (carbohydrate, lipid, protide). At the usual temperatures on the earth's surface, rocks are solid, but at higher temperatures they can be liquid like the lava of a volcano.

B- Minerals

Rocks are made up of basic bricks: minerals.

Ex: quartz, feldspars, micas, olivine, amphiboles, pyroxene, clay minerals.

If a rock is made up of a single mineral it is called monomineral rock.

Ex: pure limestone (CaCo3), gypse, silica sand.

If a rock is made up of several minerals it is called a mineral polished rock.

For example: granite consists mainly of three types of minerals: micas, feldspars, quartz. Each mineral has a precise chemical composition.

Ex: Silice (Sio2); calcite that makes up limestone (CaCo3).

Minerals are mostly in the form of crystals, a crystal is characterized by a crystalline network in which the atoms are assembled geometrically. When mineral matter or minerals are not organized in a crystalline network we speak of a morfle structure or worms.

Ex: in volcanic rocks that have cooled rapidly which prevents the crystallization of minerals, so the majority of minerals contain silica and aluminum. Silica is a combination of silicon and oxygen silicon, oxygen and aluminum are therefore the three main constituents of the Earth's crust.

C- The classification of rocks

The geologist classifies rocks according to their origin and composition, there are three main types of rocks:

1- Magmatic rocks, come from the cooling of a magma, they are called volcanic when they form during eruptions on the earth's surface or plutonics when they form by cooling and crystallization in depth

2- Sedimentary rocks are born on the earth's surface, usually by depositing material at the bottom of a sea on the coast in a delta or more rarely on the surface of a continent, the materials that make up these rocks (sediments) most often come from erosion of other rocks.

3- Metamorphic rocks are former pre-existing rocks (sedimentary or metamorphic magmatics that have been transformed at depth by increasing pressure and temperature most commonly during the

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