The plate tectonics
The Plate Tectonics is the most important technology ever made and is an idea that explains the global and what's happening to it. The Earth's surface is made up of bunch of large plates like pieces of a large jigsaw puzzle. The plates always move at a few centimetres a year. Also, the ocean floor is always moving too, spreading from the centre and sinking at the edges. The Convection Currents under the plates in different directions. The heat that takes the convection currents is radioactive decay which is happening deep inside the Earth. The edges of the plates are places where most of the dangerous events happen, such as earthquakes, volcanoes, and mountain building.
http://www.oregon.gov/DSL/SSNERR/docs/EFS/EFS26platetect.pdf?ga=t
http://www.moorlandschool.co.uk/earth/tectonic.htm
http://www.moorlandschool.co.uk/earth/tectonic.htm