The Impact of Plate Tectonics Caribbean Society and Culture

PLATE TECTONICS

The Impact of plate tectonics Caribbean society and culture

The Caribbean What is plate tectonics • The theory that the earth’s crust is made up of a series of rigid plates which float on a soft layer of the mantle and are moved by convection currents in the earth’s interior.

• The study of the movement of the plates on the earth’s surface and the resultant landforms.

Why plate tectonics is useful • Plate tectonics helps to explain many geological events, such as earthquakes and volcanic eruptions as well as mountain building and the formation of the oceans and continents.

Size of plates • Largest plates: the Pacific plate, the North American/Atlantic plate, the Eurasian plate, the Antarctic plate, and the African plate.

• Smaller plates: the Cocos plate, the Nazca plate, the Caribbean plate, and the Gorda plate.

• Plate sizes vary: The Cocos plate is 2000 km (1400 mi) wide; the Pacific plate is almost 14,000 km (nearly 9000 mi) wide.

Rate of plate movement • Tectonic plates move at an average speed of 2 – 3 inches (4 – 7 cm) per year.

• Movement is slow and continuous and has been taking place for millions of years

Components of the layers • The inner core is made up of dense iron; the outer core is made up of liquid iron.

• The lower mantle is made up of molten rock surrounded by partially molten rock in the asthenosphere. • Part of the upper mantle and crust (lithosphere) is made up of solid rock. It is a rigid layer.

Why do plates move? • The upper mantle and crust (lithosphere) lie on the lower mantle which is fluid. The rocks in the lower mantle (asthenosphere) move in a fluid manner because of the high temperatures and pressures in it.

• Currents in the lower mantle form convection cells which cause the plates to float.

Types of plate boundaries/movements The region where plates meet is called a boundary

1. Divergent plate boundaries • Occur where two plates are moving apart from each other. In the oceanic crust, this process is called seafloor spreading. Magma, or molten rock material, rises to the sea floor surface along the rupture and forms new oceanic crust.

• On land, divergent plate boundaries create rift valleys—deep valley depressions formed as the land slowly splits apart.

2. Transform plate boundary • The plates slide past or slip alongside each other.

• A transform boundary is located where the Caribbean plate and South American plates meet Transform and divergent plate boundaries.

3. Convergent boundary Also known as destructive boundary or subduction zone)

• Plates move towards one another; the plates are consumed, or recycled back into the earth’s mantle.

• Earthquakes, volcanoes, oceanic ridges, deep sea trenches, island arcs, (e.g the West Indies, the Japanese islands), and fold mountains occur at convergent boundaries A convergent boundary

• Molten material comes to the surface and forms islands

A convergent boundary

Formation of volcanoes or fold-mountains