Hot Spots
The surface of the Earth is made up of about 14 rigid plates. When two plates collide, one plate usually sinks beneath the other forcing the other deep into the mantle of the Earth. This causes the sinking plate to melt which forms magma, that will rise and form volcanoes on the plate above. This process makes the volcanoes around the world and occurs a lot in the Ring of Fire which is in the Pacific Ocean. The Hawaiian Islands are a volcanic chain of islands. The volcanoes were once active but now they are extinct. They each formed an island then became extinct. Where two plates move apart, magma rises and fills in the space which contributes to hotspots. This occurs deep on the ocean floor. Hot spots cause volcanoes to form over a certain area and will either build islands or they will just add more to the sea floor. A mid ocean ridge expands the sea floor with magma coming out and forcing the floor to spread while a subduction zone causes the sea floor to get smaller.