Q:

How do igneous rocks form?

A:

Igneous rocks are formed when magma crystallizes and solidifies. After this transition from liquid to solid, igneous rocks are classified as either intrusive or extrusive.

In order for an igneous rock to be considered intrusive it must undergo the change from a liquid to a solid state inside of the Earth. Due to the high temperatures inside the Earth, this process can take thousands or even millions of years. This type of igneous rock tends to be much larger and has a coarse texture.

Extrusive rocks are usually found near volcanoes or fissures in the Earth's crust where magma has erupted. These tend to be much smaller and have a very smooth texture. Obsidian is one of the most well-known, and also one of the most common of the extrusive igneous rocks.

Sources:

  1. usgs.gov
  2. ncdcr.gov

Is this answer helpful?

Similar Questions

  • Q:

    What are igneous rocks used for?

    A:

    Igneous rocks are often used for construction because of their durability. Igneous rocks can also be separated to access the various valuable metals and minerals inside them. Igneous rocks form as magma comes to or near the surface of the Earth; cooling and hardening because of its distance from the inner parts of the Earth where magma forms.

    Full Answer >
    Filed Under:
  • Q:

    How does magma form ?

    A:

    Magma forms when rocks in the mantle melt due to changes in pressure or the addition of water. Although temperatures in the earth's mantle are much hotter than melting temperature, there is not a layer of magma or molten rock under the earth's surface at any given time because there is too much pressure for rock to melt. Rather, magma forms here and there because of certain changes.

    Full Answer >
    Filed Under:
  • Q:

    How do rocks form?

    A:

    Rocks are formed in three primary ways, and each method produces rocks with different characteristics. Rocks are either classified as sedimentary, igneous or metamorphic, depending on the manner in which they were formed. Most rocks encountered in everyday life are sedimentary, although some igneous rocks, such as granite, are also common.

    Full Answer >
    Filed Under:
  • Q:

    Where can igneous rocks be found?

    A:

    The most common type of igneous rock, basalt, also known as malfic rock, can be found on oceanic plates at divergent plate boundaries. Intermediate and felsic igneous rocks show up along continental margins, as well. Because igneous rocks form from the cooling of lava and magma, they can be found around areas where volcanic activity is or has been present.

    Full Answer >
    Filed Under:

Explore