Plate Tectonics

The earth’s uppermost surface, the crust, is divided into multiple parts known as tectonic plates. These plates can be either oceanic or continental with oceanic crust being more dense.

There are 7 major tectonic plates and 6 minor ones.

Major Plates

• African Plate
• Eurasian Plate
• Indo-Australian Plate
• Nazca Plate
• North American Plate
• Pacific Plate
• South American Plate

Minor Plates

• Antarctic Plate
• Australian Plate
• Cocos Plate
• Caribbean Plate
• Indian Plate
• Philippine Plate

Tectonic Map of the Caribbean

Types of Plate Boundaries

Plate boundaries are the margins where two plates meet. There are 3 types of plate boundaries : convergent, divergent and transform classified based of their direction of movement. Earthquakes often occur at these boundaries.

Convergent Plate Boundary

At a convergent boundary the plates are moving towards each other. At convergent boundaries if plates have different densities, for example the Naca Plate which is oceanic and more dense converges with the South American Plate. The oceanic crust is more dense and thus subduction occurs where the plate moves down and breaks up mixing with magma rising to form volcanoes and fold mountains.

Divergent Plate Boundary

Divergent plate boundaries are moving away from each other (diverging). An example of this is the North America Plates and Eurasian Plates which are moving away from each other. At the centre of the Atlantic Ocean where the two plates meet, magma rises out as the plates move away rising to form submarine volcanoes and ridges and in some instances volcanic islands such as the Azores and Iceland. This formation is known as the Mid-Atlantic Ridge.

Transform Plate Boundary

Transform Plate boundaries are where two plates slide past each other. Slight movements along a transform fault can result in severe earthquakes. A common example of this is the very active San Andreas Fault in California, U.S.A. and another example is where where the Caribbean Plate and South American Plate slide past each other in Trinidad and offshore Venezuela.