GEOL 101 Chapter Notes - Chapter 5: Intrusive Rock, Extrusive Rock, Laccolith
Document Summary
Igneous rocks form by solidi cation of magma. Texture- refers to sizes, shapes, and arrangement of different components: most obvious are crystals visible to naked eye. Vesicles- small holes: form when gases dissolved in magma accumulate as bubbles. For a porphyritic texture to form, magma needs suf cient time in subsurface magma chamber to grow visible crystals. Geologists organize igneous rocks according to the size of crystals and the kinds of minerals in a rock. Felsic= light color, abundant quartz and feldspar. Ma c= dark color, minerals rich in fe and mg. Classi cation of igneous rocks mostly considers the composition of the rocks and the size of crystals in the rock. !1: the igneous process begins when magma forms by melting at depth, followed by movement of the magma toward the surface and then solidi cation of the magma into solid rock.
