Q:

How do rocks form?

A:

Quick Answer

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.

Know More

Full Answer

Sedimentary rocks are formed over thousands or millions of years as fine particles are compressed to form stones. As the layers accumulate, they impart incredible pressure on the bottom layers. Sandstone, limestone, shale and gypsum are all examples of sedimentary rocks. Sedimentary rocks often form in deltas and rivers because the constant flow of the river drags sediments from the river bed and deposits them in a confined area.

Igneous rocks are formed when molten rocks cool. Magma and lava spewing from volcanoes are the two most common source for igneous rocks. Granite, pumice, obsidian and scoria are all examples of igneous rocks.

Metamorphic rocks begin as either sedimentary or igneous rocks. Sometimes such rocks end up being moved into the deep parts of the Earth’s crust, where temperatures are high and pressures are extreme. These unusual conditions serve to heat and change the rocks. Marble, slate and gneiss are examples of metamorphic rocks.

Learn more about Geology

Related Questions

  • Q:

    How is an archipelago formed?

    A:

    Archipelagos form when underwater volcanoes continually produce molten magma that cools and builds up to eventually form a group of islands. Although archipelagos can form by erosion or by the movement or evaporation of water, volcanic activity is the most common cause of archipelago formation.

    Full Answer >
    Filed Under:
  • Q:

    What are metamorphic rocks?

    A:

    Metamorphic rocks are formed when the properties of existing igneous or sedimentary rocks are altered by contact with heat or pressure. They are typically found deep underground where the conditions necessary for their formation exist.

    Full Answer >
    Filed Under:
  • Q:

    What are some facts about rocks?

    A:

    Rock is the primary component of the Earth's crust. Although soil, sand and other natural materials are similar to rocks, they are not actually rocks and are classified as derivatives of rocks. Minerals are necessary to form nearly all types of rock, and most include more than one mineral. Metals are also found in many rock types.

    Full Answer >
    Filed Under:
  • 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.

    Full Answer >
    Filed Under:

Explore