HOW DO PLATE TECTONICS WORK

HOW DO PLATE TECTONICS WORK?

Tectonic plates are large plates of rock that make up the foundation of the earth's crust and the shape of the continents. The tectonic plates comprise the bottom of the crust and the top of the earth's mantle. There are ten major plates on the earth like the African plate or the Eurasian plate and many more minor ones like the cocos plate or the nazca plate. They float on a plastic-like part of the earth's mantle called the asthenosphere. The plates are most famously known for being the source of earthquakes.

The tectonic plates are about 100 km (60 miles) in thickness, with continental plates tending to be thicker than oceanic ones. The composure of the two types of plate is also quite different. Oceanic plates consist of thicker basaltic rocks, compressed by the pressure of kilometers of water. Contintental plates have a lower average density, containing granitic rocks with a heavy composition of aluminum and silica.

The mantle underneath the tectonic plates is constantly recirculating, causing the plates to float around slowly in a process called tectonic drift. This process was described well by the theory of plate tectonics, which solved several scientific dilemmas about the distribution of species when it was introduced. When plates push up against each other, they create mountain ranges and volcanoes.

THE TECTONICS PLATES

Over time, plate tectonics has caused the world's continents to be reshaped. Every continent on earth was once part of an ancient supercontinent known as Pangaea, and Antarctica was once located in a temperate climate. Marine fossils can be found on the peaks of the world's tallest mountains. The tectonic plates continue to move slowly, but it is unlikely that their movement will

cause the world's face to change more rapidly than the growing technological influence of mankind will. One day the plates' great momentum and pressure might even be used as a source of geological energy.

This phenomen was name the seafloor spreading.

Sea floor Spreading

Sea-floor spreading is the process in which the ocean floor is extended when two plates move apart. As the plates move apart, the rocks break and form a crack between the plates. Earthquakes occur along the plate boundary. Magma rises through the cracks and seeps out onto the ocean floor like a long, thin, undersea volcano. As magma meets the water, it cools and solidifies, adding to the edges of the sideways-moving plates. As magma piles up along the crack, a long chain of mountains forms gradually on the ocean floor. This chain is called an oceanic ridge. The boundaries where the plates move apart are 'constructive' because new crust is being formed and added to the ocean floor. The ocean floor

gradually extends and thus the size of these plates increases. As these plates get bigger, others become smaller as they melt back into the Earth in the process called subduction.

pangea

There are three main types of tectonic plate boundaries, described in terms of the way that tectonic plates move relative to each other. These include transform boundaries, where plates grind parallel to each other, divergent boundaries, where plates are moving apart, and convergent boundaries, where plates press into and sometimes under each other. These plate boundaries result in faults, rift valleys, oceanic ridges, oceanic trenches, mountains, island arcs, subduction zones, volcanoes, and other geologic phenomena

.Plates can move apart - If two plates are moving apart from each other, hot, molten rock flows up from the layers of mantle below the lithosphere. This magma comes out on the surface (mostly at the bottom of the ocean), where it is called lava. As the lava cools, it hardens to form new lithosphere material, filling in the gap. This is called a divergent plate boundary.

A DIVERGENT BOUNDARY

Plates can push together - If the two plates are moving toward each other, one plate typically pushes under the other one. This subducting plate sinks into the lower mantle layers, where it melts. At some boundaries where two plates meet, neither plate is in a position to subduct under the other, so they both push against each other to form mountains. The lines where plates push toward each other are called convergent plate boundaries.

A CONVERGENT BOUNDARIE

Plates slide against each other - At other boundaries, plates simply slide by each other -- one moves north and one moves south, for example. While the plates don't drift directly into each other at these transform boundaries, they are pushed tightly together. A great deal of tension builds at the boundary.

A TRANSFORM BOUNDAR Y

The major plates group together 8 plates:

- African Plate- Antarctic Plate- Indian Plate- Australian Plate- Eurasian Plate- North American Plate- South American Plate- Pacific Plate

The minor plates group together 7 plates:

- Arabian Plate- Caribbean Plate- Juan de Fuca Plate- Cocos Plate- Nazca Plate- Philippine Sea Plate- Scotia Plate

Geologists believe that tectonic plates move from gravity. Since the plates are denser than the asthenosphere, they move. there weight causes them to slide down and go by the lower subduction zones. When the plate pushes against each other it causes plate movements. They plates do not move quickly, in fact they move as fast as your fingernail grows. That averages around two inches a year.

We can see the pangaea who is the supercontinent that form the earth 150 million years ago

The second picture shows the earth fifty million years ago.

The last picture shows the earth today.

You can see how much the earth changed over the millions of years.

The major plates group together 8 plates:

- African Plate- Antarctic Plate- Indian Plate- Australian Plate- Eurasian Plate- North American Plate- South American Plate- Pacific Plate

The minor plates group together 7 plates:

- Arabian Plate- Caribbean Plate- Juan de Fuca Plate- Cocos Plate- Nazca Plate- Philippine Sea Plate- Scotia Plate

THE PLATES TECTONICS