Chapter 2.2 Igneous Rocks Objectives: recognize magma and lava as the materials that cool to form igneous rocks. Contrast the formation of intrusive and extrusive igneous rocks Contrast granitic and basaltic igneous rocks

Formation of Igneous Rocks Formed when hot magma cools and hardens

Magma When rocks melt they form magma Located about 150 km below earth's surface Lava - when magma reaches Earth’s surface and flows from volcanoes.

2. Intrusive Rocks Rocks that form from magma below (inside) the surface

2. Extrusive Rocks Extrusive igneous rocks are formed as lava cools on the surface (outside) of Earth. Cools quickly and produces fine grained crystals - example pumice and obsidian

B. Classifying Igneous Rocks Intrusive OR Extrusive INSIDE OR OUTSIDE

Basaltic Rocks Dense, dark-colored rocks. Formed from lava that is rich in iron and magnesium and poor silica

2. Granitic Rocks Light-colored rocks of a lower density that basaltic rocks.

3. Andesitic Rocks Have compositions between those of basaltic rocks.