Three Classes of Rocks: Igneous, Sedimentary, Metamorphic 2.2 Three Classes of Rocks: Igneous, Sedimentary, Metamorphic

Rocks are made up of Minerals

Rock Definition A naturally occurring mixture of one or more minerals e.g, marble, granite, sandstone, limestone

Three Classes of Rocks Igneous Sedimentary Metamorphic

Three Types of Rocks

Igneous Rocks Igneous rocks are formed from magma (hot molten rock inside the earth). It becomes rock by the solidification of magma. Granite

Two Types of Igneous Rocks Extrusive igneous rocks form from lava (magma on the surface) cooling on the earths surface Intrusive igneous rocks form when magma cools and hardens underneath the surface (i.e., below ground)

Igneous Rocks

Igneous Rock Texture Intrusive rocks such as granite are coarse grained (can easily see the grains with the unaided eye) Extrusive igneous rocks such as basalt are glassy or fine grained

Sedimentary Rocks Sedimentary rocks are formed when small pieces of rock are carried by wind or water and settle or sink down on to rocks below them. The pressure of the layering of these sediments forms sedimentary rocks. That is why you see ‘layers’ in these rocks

Sedimentary rocks can be formed by… Fragments of rocks and shells Living material, decay of plant matter Salts that the water dissolves from rocks

Metamorphic Rocks Metamorphic = Change form Metamorphic rocks are formed by the transformation or changing of previously-existing rocks from increased temperature and pressure. These rocks start as iggi – sedi – or metti.