Geology 10 (Physical Geology)

California State University, Sacramento

Week 4: Volcanoes and extrusive igneous rocks


Upon completion of this unit students should be able to:

  • Discuss how temperature and silica content affect lava

  • Define the terms lava, viscosity, magma, vesicular, frothy, fragmental

  • Be familiar with textural terms for extrusive rocks:  glassy, finely crystalline, groundmass, porphyritic, obsidian

  • Discuss the chemical composition of basalt, andesite and rhyolite

  • Differentiate between the main types of volcanoes:  cinder cones, composite cones (stratovolcanoes), shield volcanoes, volcanic domes

Homework for week #4
Complete the on-line multiple choice quiz for Chapter four (Volcanoes).

E-mail it to me at:

Please note:  This is different from my CSUS e-mail address!


You can find the quiz by following this link:

Click on the “Resources” tab at the top of the page, and scroll down to the chapter that you want to work on.  Complete the multiple choice quiz on-line, and e-mail the results to me.

Due date for homework:  The start of class on Friday, Sept. 23

Reading Assignments

From Plummer, Carlson and Hammersley, Physical Geology, 13th edition

Chapter 4- Volcanoes and extrusive igneous rocks


Powerpoint graphics used during lectures


Week 4 graphics