Department of Earth Science |Northeastern Illinois University

ESCI 121
Fall 2006

Daily Objectives #15  (October 17, 2006)                                                                        Dr. Sanders

By the end of today’s class, you should be able to do the following:


*  Explain the relationship between cooling rate and crystal size of an igneous rock.

*  Define and describe what is meant by mafic and felsic mineralogic compositions of igneous rocks.

*  Describe the igneous rocks basalt and granite in terms of their crystal size and mineralogic composition.

New Today:

Describe the difference in viscosity between molten mafic and molten felsic material.

* Explain why molten material occurs in the earth's crust, particularly explaining decompression melting and the role of water.

* Explain how magmas of different viscosity lead to differences in eruptive style of a volcano and differences in the material erupted (including volcanic lava, gas, and pyroclastics).

* Make a profile sketch of each of the three types of volcanoes (shield volcanoes, cinder cones, and composite cones), explaining why each one has its particular shape.

* Plot volcano locations on a world map, and determine how they relate to plate tectonic boundaries.

* Describe the connection between plate tectonic environment, type of volcano that would be found there, and type of material that would be extruded from that type
* Draw a sketch showing how and why volcanoes form in a subduction zone.

Department of Earth Science | Northeastern Illinois University

© 2006 Laura L. Sanders.  Last updated October 16, 2006.