Why does magma rise to the surface

Learn more about how the earth is constructed with these classroom resources. Igneous rocks are one of three main types of rocks along with sedimentary and metamorphic , and they include both intrusive and extrusive rocks. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Twitter Facebook Pinterest Google Classroom. Article Vocabulary. Friday, October 31, Magma is a molten and semi-molten rock mixture found under the surface of the Earth.

This mixture is usually made up of four parts: a hot liquid base, called the melt ; mineral s crystal lized by the melt; solid rock s incorporate d into the melt from the surrounding confine s; and dissolve d gas es.

When magma is eject ed by a volcano or other vent , the material is called lava. Magma that has cooled into a solid is called igneous rock.

This heat makes magma a very fluid and dynamic substance, able to create new landform s and engage physical and chemical transform ations in a variety of different environment s. Earth is divided into three general layers. The core is the superheated center, the mantle is the thick, middle layer, and the crust is the top layer on which we live. Most of the mantle and crust are solid, so the presence of magma is crucial to understanding the geology and morphology of the mantle. Differences in temperature , pressure , and structural formations in the mantle and crust cause magma to form in different ways.

Decompression melting involves the upward movement of Earth's mostly-solid mantle. This hot material rises to an area of lower pressure through the process of convection. Areas of lower pressure always have a lower melting point than areas of high pressure. This reduction in overlying pressure, or decompression, enables the mantle rock to melt and form magma. Decompression melting often occurs at divergent boundaries, where tectonic plate s separate.

The rift ing movement causes the buoyant magma below to rise and fill the space of lower pressure. The rock then cools into new crust. When located beneath the ocean, these plumes, also known as hot spot s, push magma onto the seafloor.

These volcanic mounds can grow into volcanic island s over millions of years of activity. As the liquid rock solidifies, it loses its heat to the surrounding crust. Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together.

As the dense r tectonic plate subduct s, or sinks below, or the less-dense tectonic plate, hot rock from below can intrude into the cooler plate above. This process transfers heat and creates magma. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc.

Flux melting occurs when water or carbon dioxide are added to rock. These compounds cause the rock to melt at lower temperatures. This creates magma in places where it originally maintained a solid structure. Much like heat transfer, flux melting also occurs around subduction zones.

In this case, water overlying the subducting seafloor would lower the melting temperature of the mantle, generating magma that rises to the surface. Noticeable steaming or fumarolic activity and new or enlarged areas of hot ground.

Subtle swelling of the ground surface. Small changes in heat flow. Lava then cools down and solidifies into rock pretty fast.

The melting point of Diamond at about , atm is K, which is much higher than the temperature of lava. So, it is impossible for lava to melt a diamond. The edges of tectonic plates form an ideal location for volcanoes to form. This becomes a ready supply of new molten magma, which can result in more volcanoes. Learn more about this in the article Plate tectonics, volcanoes and earthquakes.

Once the molten mantle rock forces its way through the crust, it eventually erupts through the volcano as lava. This lava cools and forms rocks that scientists study to try and tell them more about what is happening to cause volcanic eruptions and how the mantle is stored under a volcanic area. Explore the different types of explosions that occur in the article Types of volcanoes.

Scientists are currently working on finding out what triggers eruptions and what causes the magma to be released. Magma rises in three different ways. Magma can rise when pieces of Earth's crust called tectonic plates slowly move away from each other. The magma rises up to fill in the space. When this happens underwater volcanoes can form. Magma also rises when these tectonic plates move toward each other. When this happens, part of Earth's crust can be forced deep into its interior.

The high heat and pressure cause the crust to melt and rise as magma. A final way that magma rises is over hot spots. Hot spots are exactly what they sound like--hot areas inside of Earth. These areas heat up magma.