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    Extrusive igneous rocks show up as volcanos. Intrusives exist as bodies of igneous rock below ground, such as batholiths, dikes, and sills. Many excellent web pages exist on volcanoes, but as with many things on the web the problem is not finding information, it is sorting through the avalanche of information that exists, and then remembering where you found it. The links below to volcanos are generally very good to excellent.
    Web sites for intrusive igneous bodies are not common, and to date I have not found any that have good pictures of the various intrusive types, such as batholiths, sills, dikes, etc. Many pages discuss the kinds of rocks found in the bodies (generally coarse grained ones such as granite, diorite, gabbro) but do not illustrate them.

   Volcanoes: Many excellent web sites exist on volcanoes, and most of them have abundant links to other sites.
      Volcano Types and Pictures

    Igneous Rocks:

   Intrusive Igneous Rocks:

These next few sites provide general access to numerous other web pages.
Volcano Lesson Plans http://www.realinsurance.com.au/Article-Library/Volcano-Lesson-Plans.aspx
    A nice collection of links for sites containing help for teaching about volcanos, grades 3 - 12

Alaska Volcano Observatory http://www.avo.alaska.edu/
   Alaska has over 40 active volcanoes, this site maps and illustrates them.

The Volcanic Home Page

The Volcano Information Center http://magic.geol.ucsb.edu/~fisher/
   Lots of basic information.
   Scroll down to " Volcano Topics" . This is not fancy but it contains a lot of basic information well presented.

The Volcanic Jump Station
   An alphabetical listing of links concerning volcanoes and igneous rocks.

More specific sites (mostly taken from within the above sites)

Volcanoes by Robert I Tilling http://pubs.usgs.gov/gip/volc/
   This page nicely summarizes volcanoes on earth.
   Also has a very good page illustrating " Principle Types of Volcanoes" http://pubs.usgs.gov/gip/volc/types.html

Volcano forms http://magic.geol.ucsb.edu/~fisher/volcano.htm
   Nice descriptions of the different kinds of volcanoes with pictures.

Numerous pictures of volcanoes - they are not identified as to type, but with the above page you can probably learn to recognize them.

The volcanic photo archive

   These site is from the University of British Columbia for their introductory petrology (study of rocks) page. Some of it is still under constructions, but there is a lot of information here.

   This page contains definitions of many igneous rock terms.

http://ucaswww.mcm.uc.edu/geology/maynard/INTERNETGUIDE/appende.htm    General introduction to igneous rock principles. Lots of information but few pictures.

   A few pictures of igneous rocks, some in hand samples, some field pictures.


    So far I have found no site showing an archive of illustrations of intrusive igneous bodies. If you find one let me know. Otherwise, I guess I will just have to do it myself someday.
    In the meantime, there is this drawing taken from an old physical geology textbook. Not in color (yet) but still a good illustration.
    Some links that approach the subject of intrusive igneous rocks are below.

   Igneous Rock Occurence from the University of Saskatchewan

   Encyclopedia Britannica article

   From Tulane University

   Go to Igneous Rock Home Page

Last Update: 9/29/00

e-mail: (Fichtels@jmu.edu)