ROCKS OF THE EARTH

ROCKS OF THE EARTH:

The earth’s crust consists of rocks and rocks consist of combination of different minerals and in turn minerals are made up of one or more element, some minerals are themselves elements, example Gold, Diamond, Sulphur we don’t have combination of these elements.

Definition: Rocks are aggregate of minerals in solid state.

Rocks can be classified according to their origin and age, there are three types of rocks which classified based on their mode of formation.

TYPES OF ROCKS

1.      Igneous rocks

2.      Sedimentary rocks

3.      Metamorphic rocks

1.      Igneous rocks

The name igneous is a Latin word which means fire. This types of rocks also known as mother of rocks when molten rocks called magma cools and solidifies either within or outside the earth’s surface. These types of rocks are categorized in two types.

TWO CATEGORIES OF IGNEOUS ROCKS

1.      Intrusive igneous rocks, these are type of igneous rocks that formed when magma cools and solidifies deeply inside the earth. In this magma cools very slowly hence the rocks formed tend to have large crystals, these also are categorized into two types that are Plutonic & Hypabyssal, Plutonic are those formed very deep while hypabyssal are those formed near the extrusive igneous rocks, example of these rocks are Granite, Diorite, Gabro etc.

2.      Extrusive igneous rocks (volcanic): This is formed when magma cools and solidifies above the earth’s surface, lava solidifies very quickly hence the crystals formed are very small, example of these rocks are Basalt, Rhyolite, Andasittle, Obsidian.

WEATHERING

                                              WEATHERING

Def:

Weathering is the process of weathering, disintegration or fragmentation of rocks into small particles.

Rocks on the earth’s surface are weathered by different type where we get type of weathering as follows:

1. physical/mechanical weathering
2. chemical weathering
3. biological weathering

                                  1. PHYSICAL / MECHANICAL WEATHERING

This is type of weathering whereby the rocks disintegrate in small particles without chemical reaction.

Physical weathering occurs in different type such as:

1. temperature change (exfoliation)
2. frost action
3. alternate wet and dry
4. biotic factors
5. burrowing animals

STRUCTURE OF THE EARTH

STRUCTURE OF THE EARTH

The shape of the earth

The shape of the earth is flattened sphere; it is silinatical with an egg.

WHY EARTH IS FLATTENED SPHERE?

·         The diameter through the equator and poles varies. The diameters are 12713 km.

·         The influence of winds from High Pressure to low pressure erodes the poles materials and deposit on the equator.

·         Earth’s movement which are rotation and Revolution.

POINT TO PROOF THAT THE EARTH IS SPHERE

·         When a ship rises from a distance, smoke is seen first, as it comes nearer the most is seen then the whole ship is seen.

·         Rise and set of the sun, the sun does not rise and set at the same time in all countries of the world.

·         The shadow of the earth appears on the moon when the earth is between the sun and the moon.

·         Telescoping observation reveals that all heavenly bodies viewed from any angle shows circular outlines all heavenly bodies are sphere.

·         Photographs taken from spaceship at every high altitude clearly show that the earth has spherical shape.

FORCES THAT AFFECT THE EARTH

FORCES THAT AFFECT THE EARTH FROM WITHIN INTERNAL FORCES

The crust of the earth consists of the solid rocks, it subjected to internal forces which cause the earth to move either vertically or horizontally.

The movement can be quite or violent and result in the formation of different physical features.

CAUSES OF THE EARTH MOVEMENT WITHIN THE EARTH’S SURFACE.

i.                     Different in temperature within the earth.

ii.                   Different in density.

iii.                  Chemical composition of rock.

TYPES OF FORCES

There are three types of forces within the earth’s crust.

1.      COMPRESSIONAL FORCE

Is when the pieces of the earth’s crust move towards each other (converging) and this may result into folding of the earth’s crust that result into  the formation of Plateaus and Basins  example, Lake Victoria Basin,  Congo Basin, Chad Basin, Bolivia Plateau, Tibetan Plateau etc.

Effect of vertical feature in environment.

i.                     Moderation of climate

ii.                   Change of relief

iii.                  Mineral exploitation (deposition)

iv.                 Soil PH.