Magma is molten rock that is found below the earth’s surface. The temperature at which rock melts is affected by its composition, pressure, and water. As a result, magma forms and either feeds volcanoes or cools and crystallizes into igneous rock.
Magma is an extremely hot liquid and semi-liquid rock under Earth’s surface. Earth has a layered structure that consists of the inner core, outer core, mantle, and crust. As a result, much of the planet’s cover consists of magma. This magma can push through holes or cracks in the crust, causing a volcanic eruption. It is called lava when magma flows or erupts onto Earth’s surface.
Like solid rock, magma is a mixture of minerals. It also contains small amounts of dissolved gases such as water vapor, carbon dioxide, and sulfur. The high temperatures and pressure under Earth’s crust keep magma in its fluid state.
There are three basic types of magma:
Each type of magma has a different mineral composition. However, all kinds of magma have a significant percentage of silicon dioxide.
Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium. It ranges in temperature from about 1000oC to 1200oC (1832oF to 2192oF).
Andesitic magma has moderate amounts of these minerals, with temperatures ranging from about 800oC to 1000oC (1472oF to 1832oF).
Rhyolitic magma is high in potassium and sodium but low in iron, magnesium, and calcium. It occurs in the temperature range of about 650oC to 800oC (1202oF to 1472oF).
What part does magma play in volcanoes?
Both the temperature and mineral content of magma affect how easily it flows. In addition, the viscosity (thickness) of the magma that erupts from a volcano affects the shape of the volcano.
Volcanoes with steep slopes tend to form from very viscous magma, while flatter volcanoes form from magma that flows easily.
The movement of magma causes most earthquakes directly beneath a volcano. It is because the magma exerts pressure on the rocks until it cracks their rock.
Where does the name magma come from?
Magma comes from an Italian word that means a thick, pasty substance, which is how molten rock behaves within the Earth.
Lava, another Italian word, means to slide, which is what molten rock does once it reaches the surface.
What is the difference between magma and lava?
The distinction between magma and lava is all about location. When geologists refer to magma, they talk about underground molten rock. If this molten rock makes it to the surface and keeps flowing like a liquid, it’s called lava.