This page provides a brief outline of, lists the main points of, gives links to figures for, and lists the assigned reading for a lecture in Dr. Bruce Ralsback's GEOL 1121 class at the University of Georgia. This page is not intended as a set of lecture notes, and it cannot subsititute for a set of lecture notes. Familiarity with this page alone will not assure satisfactory grades on exams in the course.

Lecture 6 (Friday, January 18): Igneous Rocks

Brief outline of this lecture:
The three kinds of rocks
Crystallization of igneous rocks
Classification of igneous rocks
Plate tectonic settings of igneous rocks
Bodies of igneous rock
     

Main points of this lecture:
There are three fundamental kinds of rocks, as divided by their origin.
The crystal size of igneous rocks depends on how fast they cool from a magma.
How fast a magma cools depends on whether it lodges deep in the crust or reaches the earth surface.
Igneous rocks are classified by the texture and composition.
The major kinds of igneous rocks have distinctive places in which they typically form.
Basalt forms in several settings.
Bodies of plutonic rock are categorized by size and relationship to surrounding rock structure.

Figures used in this lecture:
The three fundamental kinds of rocks
Crystallization of igneous rocks
Classification of igneous rocks
Occurrence of igneous rocks
List of bodies of plutonic rocks
Diagram showing bodies of plutonic rocks

Reading assignment: pages 34-35.

Next Lecture
Email to Railsback (rlsbk@gly.uga.edu)
Railsback's main 1121 web page
Railsback's main web page
UGA Geology Department web page