THEORY OF PLATE TECTONICS.

PRESENTER: FARYAL SALEEMI.

LAYERS OF EARTH

CrustMantleCore

CRUST OR LITHOSPHERE:

Two types of crust

Oceanic crust is thinner and denser and usually darker in color.

Continental crust is lighter in weight, less dense, light in color, and tends to float over oceanic crust.

Mantle: Its beneath the crust; houses molten rock material called magma.

Outer core: composed of liquid iron and nickel; very dense material

 Inner core: composed of solid iron and nickel; extremely dense material.

ASTHENOSPHERE: The upper mantle and lower crust

(lithosphere) are referred as asthenosphere.

THEORY OF PLATE TECTONICS:

The theory of plate tectonics is that rigid lithospheric plates move across the surface of the earth. There are approximately 12 major and minor plates that move in concert with each other. Some pull apart, some push together and some move horizontally against each other

7 PLATES OF LITHOSPHERE:

The theory tells that Earth's outermost layer, the lithosphere, is broken into 7 large, rigid pieces called plates; named:

African North American South American Eurasian Australian Antarctic Pacific plates.

Brief History:

Alfred Wegner (Father of Plate Tectonics) Polar Wandering. Continental Drifting. Harry Hess Robert Palmer and Donald Mackenzie

Plate Tectonics.

CORRELATION OF AFRICA AND SOUTH AMERICA BY WEGENER

Evidence used by Wegener:

1. Shape of continents fit like a jigsaw puzzle.

2. Similar fossils on both

continents3. Mountain belts line up4. Mineral belts line up

The plates are all moving in different directions and at different speeds (from 2 cm to 10 cm per year--about the speed at which your fingernails grow)

Plate Boundaries or Margins: The place where two plates meet is called a

plate boundary. Types of Plates:

Convergent Plate Boundry Divergent Plate Boundary Transform Fault/Boundary

Convergent Plate Boundary:

When two plates move towards each other and form a subducting zone, then this is said to be as a Convergent Plate Boundary.

Types of Convergent Plate Boundaries:a) Oceanic-Continental Convergence:

• Have subduction zone• Associated deep sea trench• Volcanic arc

b) Oceanic-Oceanic Convergence:

• Have deep sea Trench• Volcanic Island arc QURIESS • Basaltic Volcanic Rock

c) Continental-Continental Convergence:

• No volcanism.• No magmatic activity.•Mountain building processes occur.

Divergent Plate Boundary:

Places where plates are coming apart are called Divergent Boundaries.

Transform Boundary:

Places where plates slide past each other are called transform boundaries.

Transform boundaries lack the spectacular features found at convergent and divergent boundaries.

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