Q:

Why does magma rise to the Earth's surface?

A:

Quick Answer

Magma rises to the Earth's surface due to a combination of differences in density with other rocks in the crust and pressure. The differences in density cause it to move upward until its density is the same as the other rocks in the crust. It then builds pressure, causing it to rise to the surface.

Know More

Full Answer

Magma is made of molten rocks and minerals. It forms in the lower crust and upper mantle layers of the Earth due to movements in the mantle, changes in temperature or contact with water or carbon dioxide under the surface. These changes cause rocks in the crust to melt, forming magma.

Sometimes, magma collects in magma chambers, and sometimes, it simply rises until its density is the same as the other rocks around it. However, once it has risen, it comes into contact with gases, forming bubbles. In some cases, the magma decompresses too quickly and the bubbles build up and create pressure. This pressure causes the surrounding rock to fracture, letting the magma rise to the surface.

Magma that is created through exposure to water can rise under different conditions. Water causes rock to melt at lower temperatures, so less pressure is involved. However, water usually enters the lower crust through subduction zones in the ocean floor, which also allow the magma to escape.

Learn more about Geology

Related Questions

  • Q:

    Where do volcanoes form?

    A:

    Volcanoes can form anywhere the Earth's crust allows magma to reach the surface. Typically, this occurs around plate boundaries, either where plates are pulling apart or where one is forcing its way under another. Weak spots can also develop away from plate edges, creating magma vents called hot spots.

    Full Answer >
    Filed Under:
  • Q:

    How does a volcano occur?

    A:

    Volcanoes occur when magma and heated gases from below the Earth's crust are channeled to the surface through fissures in the crust layer. Magma is molten rock that is called lava once it reaches the surface.

    Full Answer >
    Filed Under:
  • Q:

    What causes volcanic eruptions?

    A:

    Volcanic eruptions occur when magma builds up beneath the Earth's crust and forces its way to the surface. Natural vents in the crust allow magma passage to the surface, and eruptions occur when the magma that forms is less dense than the material above it, causing it to flow upward. In some cases, this flow is slow and steady, but it can also be rapid and violent.

    Full Answer >
    Filed Under:
  • Q:

    Where do rocks come from?

    A:

    Rocks come from magma, which is the molten material found within the earth. When magma cools, either above or below the earth's surface, it crystallizes and forms the igneous rocks that can later be changed into metamorphic or sedimentary rocks. Magma, which can be considered molten rock, is referred to as lava when it reaches the earth's surface.

    Full Answer >
    Filed Under:

Explore