We have the inner core, outer core, mantle and crust which play an important role on Earth.
The layers of the Earth are responsible for the formation of our continents. Two Hundred Fifty Million years ago most of the land mass was joined together forming a super continent called Pangaea. Through the years we had continental drift, which is the gradual movement and formation of continents (as described by plate tectonics). Continents move an average of 2cm each year. Our seven continents look the way they are because of continental drift.
The crust is very thin broken up in many pieces called plates, which float on the mantle. These plates usually slide very smoothly, but sometime stick and build up pressure and the rock snaps. When this occurs we get Earthquakes. Earthquakes can be important because of Energy (seismic energy) released during Earthquakes provides much information about the Earth’s interior. It helps us understand the changes in the earth crust. Earthquakes also tell us if volcanoes are becoming more or less active.
The Hawaii Islands were formed because of hot spot. A volcanic hotspot is an area in the upper mantle from which heat rises in a plume from deep in the Earth. High heat and lower pressure at the base of the mantle facilitates melting of the rock. This melt, called magma, rises through cracks to the surface and forms volcanoes. As the tectonic plate moves over the stationary hot spot, the volcanoes are rafted away and new ones form in their place.
Remember, the Earth is always changing, always moving. When two plates come together, it is known as a convergent boundary, which is important in building mountains where the Plates crash together to make mountains, such as the Himalayas.
Oceanic crust made of basalt is created through a divergent boundary, which occurs when two tectonic plates move away from each other.
The cycle never stops and it ensures that the planet never runs out of rocks. Like a giant recycling machine, Earth constantly creates rocks, breaks them down and converts them into new types of rock. The Earth's crust recycles itself through subduction of crustal material into the mantle and upwelling of magma from the mantle. These processes are described by plate tectonics, a commonly accepted theory that explains the large-scale movements of the Earth's lithosphere.