PLATE TECTONICS. By Alice . What are Tectonic plates?. . The Earth's surface is made up of a series of large plates (like pieces of a giant jigsaw puzzle). .These plates are in constant motion travelling at a few centimetres per year.
.The Earth's surface is made up of a series of large plates (like pieces of a giant jigsaw puzzle).
.These plates are in constant motion travelling at a few centimetres per year.
.The ocean floors are continually moving, spreading from the centre and sinking at the edges.
.Convection currents beneath the plates move the plates in different directions.
.The source of heat driving the convection currents is radioactive decay which is happening deep in the Earth.
The theory of plate tectonics has done for geology what Charles Darwin's theory of evolution did for biology. It provides geology with a comprehensive theory that explains "how the Earth works." The theory was formulated in the 1960s and 1970s as new information was obtained about the nature of the ocean floor, Earth's ancient magnetism, the distribution of volcanoes and earthquakes, the flow of heat from Earth's interior, and the worldwide distribution of plant and animal fossils.
As with continental drift theory two of the proofs of plate tectonics are based upon the geometric fit of the displaced continents and the similarity of rock ages and Paleozoic fossils in corresponding bands or zones in adjacent or corresponding geographic areas (e.g., between West Africa and the eastern coast of South America).
*Divergent- pulling apart
Where do volcanoes occur?
Volcanoes are created by destructive plate tectonics at the convergence of the boundaries of two continental plates. As the plates collide and rise together they form a mountain over a hot spot (a place where underground lava-"magma"- collects), the volcano will erupt once the pressure rises to a certain level.
Earthquakes come from the ground where a tectonic plate is either subdued (pushed under) another plate or breaks in half. When this happens a lot of energy is released shaking the ground.
To figure out just where that earthquake happened, you need to look at your seismogram and you need to know what at least two other seismographs recorded for the same earthquake. You will also need a map of the world, a ruler, a pencil, and a compass for drawing circles on the map.