Earth's structure
The Earth's crust is made up a thin layer of soil and rock. Under the oceans the denser material is called sima. Under the continents, the lighter material is called sial. The next (and thickest) layer is called the mantle. It is made of of extremely viscous material that is moved about by convection currents. This mechanism causes plates on the crust to be disturbed form time to time. The crust and the upper layer of the mantle is called the lithosphere. Beneath the mantle is the core. the outer core is semi-molten while the inner core is solid and is thought to carry temperatures of up to 4300 degrees Celsius.
The Earth's crust is made up a thin layer of soil and rock. Under the oceans the denser material is called sima. Under the continents, the lighter material is called sial. The next (and thickest) layer is called the mantle. It is made of of extremely viscous material that is moved about by convection currents. This mechanism causes plates on the crust to be disturbed form time to time. The crust and the upper layer of the mantle is called the lithosphere. Beneath the mantle is the core. the outer core is semi-molten while the inner core is solid and is thought to carry temperatures of up to 4300 degrees Celsius.
Theory of Plate Tectonics
The theory posits that the Earth's crust is divided into several plates which float atop the asthenosphere or mantle. These movements are caused by convection currents in the mantle, arising from the hot core. The interactions between tectonic plates gives rise to several notable features features including mountain ranges, deep sea trenches, island arcs, volcanoes and earthquakes.
The theory posits that the Earth's crust is divided into several plates which float atop the asthenosphere or mantle. These movements are caused by convection currents in the mantle, arising from the hot core. The interactions between tectonic plates gives rise to several notable features features including mountain ranges, deep sea trenches, island arcs, volcanoes and earthquakes.
Click on the arrow to view this You Tube video that summarizes the theory of plate tectonics.
Click on the arrow to view the Slideshare which covers the occurrence and distribution of features resulting from tectonic movements.