Plate Tectonics Overview

Study Notes

Plate Tectonics Overview

Plate tectonics refers to the gradual movement of the Earth’s crust, averaging between 1 to 15 centimeters per year.
The term "tectonic" derives from the Greek word meaning "carpenter" or "builder."

Structure of the Earth

Earth consists of 58 crustal plates categorized into:
- Primary Plates: Africa, Eurasian, Indo-Australia, North America, Pacific, South America, Nasca.
- Secondary Plates: Caribbean, Nasca, Philippine Sea, Arabian, Cocos, Scotia, Juan de Fuca.

Continental Drift Theory

Proposed by Alfred Wegener in 1915, suggesting that continents were once joined as a supercontinent named Pangea.
Pangea was surrounded by the vast ocean Panthalassa and eventually split into Laurasia and Gondwanaland, leading to modern continents.

Earth's Composition

Earth includes both continental and oceanic lithospheres.
Continental margins represent the edges of cratons, stable and ancient portions of the continental crust.
The oceanic crust consists mainly of basalt and gabbro.

Formation of Oceanic Crust

Oceanic crust develops from volcanic eruptions, producing:
- Basalt: Formed externally from volcanic eruptions.
- Gabbro: Formed internally within the volcano.

Convection Processes

Tectonic plate movement is driven by convection currents, resulting from heat within the Earth.
Hot convection currents can lead to the movement of tectonic plates.
Convection is a heat transfer process where warmer material rises and cooler material sinks.

Mantle Convection Theory

Proposed by Arthur Holmes in 1929, it posits that older rock gets gravitationally pulled downward into the mantle.
Slab-pull theory describes the subduction of older rock into the mantle due to gravitational forces.

Seismology and Plate Movement

Seismological instruments can detect subsurface movements, producing 3D images of tectonic activity.
The mantle's heat and pressure dynamics can cause magma to break free, prompting the drift of tectonic plates in opposing directions.

Description

Explore the fascinating world of plate tectonics, which describes the continuous movement of Earth's crustal plates. This quiz covers primary and secondary plates, their movements, and their geographical significance. Test your knowledge on the fundamental concepts of geology!