Earth’s Structure and Volcano

How deep below is the oceanic crust

5 kilometers deep

How deep below is the continental crust?

20-65 kilometers deep

What is the distance beneath the crust to the center of the Earth?

More than 6,400 kilometers

What are the two theories of Continental Movement

The Continental Drift Theory

Plate Tectonics Theory

Continental Drift Theory

Proposed by Alfred Wegener in 1910

What is the continent drift theory

The continental drift theory is states that all the continental were all joint together called Pangaea and later broke into two called Laurasia and Gondwanaland

What is the plate tectonics theory

The plate tectonics theory states that the Earth’s crust is divided into several plates that glides over the mantle and moves relatively to each other

When was the continental drift theory presented

Was presented in the 1960’s as response to Wegener’s Continental Drift

Why was Alfred Wegener’s theory criticized

He was not a geologist but a meteorologist/ economist/ explorer and could not explain the mechanism which caused the continents to drift apart

Evidence for Plate Tectonics

1. MAGNETISM(OR PALEOMAGNETISM)

2. CORRESPONDING ROCK STRATA

3. FOSSILS (EXAMPLE: MESOSAURUS) South America and Africa

4. DIRECT MEASURE OF PLATE MOVEMENT

5. SESMCACTVITY

6. EARTHQUAKE FOCH

7. FIT OF CONTINENTAL COASTS?

What are the 4 stages of folding and resulting landforms

Syncline- rocks are folded downwards

Anticline- rocks are folded upwards

Overfolds and recumbent- rocks are folded in complex pattern

Overthrust- rocks are folding and faulting

What are the 4 intrusive volcanic features

Dyke

Sill

Batholith

Laccolith

What does a vertical sheet of magma form

Dyke

What does a horizontal sheet of magma form

Sill

where does a plug form

A plug forms at the vent of an extinct volcano

What is a batholith

A batholith is formed when a large mass of magma cools beneath the earth’s surface

What is a laccolith

A laccolith is formed when magma pushes between rock layers causing the surface to push upwards

What is a caldera

A caldera is a huge crater formed when a volcano blow its top off due to a violent eruption

What is a deep basin

A deep basin is formed when a caldera is formed and the magma chamber has been emptied by the violent eruption

What is a crater lake

A crater lake is formed when a deep basin is filled with water