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 Railsback'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 7 (Monday, January 28 and Wednesday, january 30): Volcanoes and Volcanism

Brief outline of this lecture:
Kinds of volcanic materials.
Kinds of volcanoes or volcanic features.
Plate tectonic settings of volcanoes.
Columnar jointing.
Volcanism's long-term significance.      

Main points of this lecture:
Volcanic materials (lava, ash, etc) can be related to whether the magma from which they form is mafic or sialic.
Kinds of volcanoes be related to whether the magma from which they form is mafic or sialic.
Environmental hazards related to volcanism common relate to whether the magma being erupted is mafic or sialic.
Locations of many volcanoes are predictable from Plate Tectonics.
Columnar jointing results from localized contraction of cooling lava.
A caldera forms as the upper parts of a volcano collapse when a magma chamber empties under that volcano.
Volcanoes can influence and have influenced the global environment at annual to geologic time scales.

Figures used in this lecture:
Kinds of volcanic material
Kinds/Forms of volcanoes
Kinds/Forms of volcanoes II
Plate Tectonic settings of volcanoes
Sizes of pyroclastic eruptions
An explanation of columnar jointing
The long-term significance of volcanism

Reading assignment: Chapter 5.

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Railsback's main 1121 web page
Railsback's main web page
UGA Geology Department web page