Pool page 2

The most common definition that we hear for a volcano is a mountain that spews lava, but this is not an entirely accurate description. A volcano is a rupture in the Earths crust that allows lava, ash, or gases to be released from a magma chamber below. On Earth, volcanoes occur because of plate tectonics. In the most simple of terms, the Earth is made up of many plates that move around the surface. Some plates will have hot spots that spit out lava. The lava builds on itself creating a volcano. Areas that we know to be volcanic usually have lines of mountains, such as the Aleutian or the Hawaiians. The lines these islands make are examples of moving plates. Depending on the topography of the area, different types of volcanoes are formed. There are three main types. Composite, Cinder Cone, and Shield.

The type that most think of when they consider a volcano is a composite volcano. This type is very large and consists of lava layers mixed with sand and cinders, which is volcanic ash that takes the appearance of gravel. Famous composite volcanoes include Vesuvius, Krakatoa, Fujiyama, and Mount Saint Helens.

The next common volcanoe is the Cinder Cone. These are relatively small and steep and do not have very much lava that makes up the volcano. Instead there is a tube that leads to the top, usually ending with a crater on the peak. A few examples of these are Mt. Dakula, Mount Leara, Cerro Negro, and Twin Buttes

The third and final common volcano is the shield volcano. This is what the Hawaiin islands are made out of. They are huge volcanoes that dump lava that freezes and becomes part of the growing mountain. Mauna Loa is a shield volcano that is also the largest mountain in the world. They often not steep and have a crater at the peak.

Here are a few picture examples of these three volcano types. How of these spew lava is related to pressure, gravity, and rates of flow, which we will be getting into on the next couple pages!