Plate Tectonics Theory

Theory of Plate Tectonics

Explains the movement of the lithosphere and the formation of continents.

Continental Drift Theory

Proposed by Alfred Wegener, it states that a supercontinent called Pangaea existed and began to break up 225 to 200 million years ago.

Isostasy

The state of balance and equilibrium within the earth's crust, where the upper lithosphere floats on denser magma.

Tectonic Plates

Massive slabs of solid rock that surround the Earth's surface, derived from the Greek word 'tekton' meaning carpenter or builder.

Plate Tectonics Theory

The unifying theory of Geology that explains changes in the Earth's surface over time, earthquakes, volcanic activities, and the location of mountain ranges.

Raisin Theory

Compares the Earth to a grape that contracted into a raisin due to cooling after the Big Bang, causing crustal movements.

Pangaea

The name of the supercontinent that existed during the Permian period before breaking apart.

Rodinia

A supercontinent that existed about 1,100 million years ago before Pangaea.

Panthalassa

A vast ocean that surrounded Pangaea.

Tethys Sea

The sea that separated the two supercontinents, Laurasia and Gondwanaland.

Laurasia

One of the two supercontinents that formed when Pangaea began to split.

Gondwanaland

The other supercontinent that formed alongside Laurasia when Pangaea began to split.

Asthenosphere

The semi-fluid layer beneath the lithosphere on which tectonic plates glide.

Earth's Movement

The movement caused by the magnetic field and tectonic activity.

Earthquake

A sudden shaking of the ground caused by the movement of tectonic plates.

Volcanic Activity

The eruption of molten rock from beneath the Earth's crust, often associated with tectonic plate boundaries.

Mountain Ranges

Elevated landforms that can form as a result of tectonic plate collisions.

Continental Movement

The shifting of continents over geological time due to tectonic forces.

Surface Changes

Alterations to the Earth's surface that occur over time due to geological processes.

Dynamic Earth

The concept that the Earth is constantly changing due to tectonic activity.

Static Earth

The idea that the Earth does not change, which is contradicted by the theory of plate tectonics.

Iceland

The only inhabited island where tectonic plates and ocean ridges are visible on land.

Major Plates

Fifteen plates are identified as major plates, including seven primary plates.

Primary Plates

African Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, South American Plate, and Antarctic Plate.

Secondary Plates

Plates that have broken off and continue being broken up from primary or secondary plates.

Lithosphere

The main layer involved in tectonic activities.

Oceanic Lithosphere

Associated with the oceanic crust.

Continental Lithosphere

Associated with the continental crust.

Continental Crust

Made up of lower-density materials, like granitic rock.

Oceanic Crust

Made up of basalt and gabbro rocks.

Thickness of Continental Crust

Ranges from 10 - 70 km.

Age of Oceanic Crust

Oldest age is 200 million years.

Density Comparison

Continental crust is less dense than oceanic crust.

Granitic Rock

The primary composition of continental crust.

Basaltic Rock

The primary composition of oceanic crust.

Sial

Refers to the continental crust rich in silica and aluminum.

Sima

Refers to the oceanic crust rich in silica and magnesium.