Department of Earth Science |Northeastern Illinois University

ESCI 121
Fall 2006

Review Sheet for Exam #3  (November 9, 2006)                                                             Dr. Sanders

For the exam, you should be able to do the following:


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

* Explain why molten material occurs in the earth's crust, particularly explaining 1) decompression melting, and 2) the role of water ("volatiles") in the melting material.
* 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.

* Explore the Mount Saint Helen's web cam (click the volcano icon on the ESCI Department home page) and the Kilauea web cam.


*  Explain why and how rocks can undergo metamorphism, and in what plate tectonic setting it might take place.

*  List and describe two major textural changes that occur when rocks undergo metamorphism.

*  Examine hand samples and describe the properties of common minerals that occur in metamorphic rocks.  (Examples used in class: numbers 4, 5, 7, 9, 16, 23, 25, 30, 31, 39).

*  Examine hand samples of metamorphic rocks, describe their features, and use a key (textbook p. 73) to identify their names.  (Examples used in class: 101, 105, 115, 116, 131, 140, 147).

*  List the names of the metamorphic rocks that result from metamorphism of sandstone, granite, limestone, and shale, and tell how each of these protoliths is different from and similar to the metamorphic rock.

* Complete the table, showing which metamorphic rocks form from which protoliths, and circling the appropriate choice in the final two columns.
Name of Protolith
(Parent Rock)
Name of
Metamorphic Rock
The protolith is a(n) _____ rock.
(circle one)
The metamorphic rock is ______ 
(circle one)

sedimentary / igneous / metamorphic
foliated / not foliated

sedimentary / igneous / metamorphic foliated / not foliated

slate sedimentary / igneous / metamorphic foliated / not foliated

quartzite sedimentary / igneous / metamorphic foliated / not foliated
sedimentary / igneous / metamorphic foliated / not foliated

anthracite ("hard coal") sedimentary / igneous / metamorphic foliated / not foliated


Sketch a diagram illustrating the materials and processes of the rock cycle.


*  Describe how a seismograph works, and explain why every seismic monitoring station actually has three seismographs.

*  Tell how P-waves and S-waves differ in terms of velocity, the way they travel, and whether or not they can travel through liquids.

*  Explain how earthquake waves helped us learn that the outer core is liquid, using the term S-wave shadow zone.

* Explain the significance of the P-S lag.

* Given the velocity of P-waves and S-waves, calculate how long it would take each type to travel a given distance (e.g. 100 miles).

* Given data on the arrival times of P-waves and S-waves at several seismic monitoring stations, calculate the P-S lag.

* Given the P-S lag for an earthquake detected at several seismic monitoring stations, calculate how far from each station the epicenter was.

* Given the distance to the epicenter of an earthquake detected at several seismic monitoring stations, locate the epicenter.

*  Explain why it is necessary for you to have measurements from at least three seismic monitoring stations to find the epicenter of an earthquake.

* Put maps of earthquake foci into a grouping based on patterns of distribution and depth.  For each group, explain what all the maps in that group have in common.

* Explain the relationship between patterns of earthquake distribution and depth with type of plate boundary:

        1)  divergent            2)  transform        3)  convergent with no subduction
        4)  convergent with subduction (note: using the map of focus depths, tell which plate is the subducting one)
* Identify areas that have earthquakes, but are not located on boundaries, and explain why earthquakes occur in these places.

* Given a map of an unknown area showing numerous earthquakes, suggest what the plate tectonic setting might be. 

        Some possible examples (you probably can think up others!):

             > A map showing parallel bands of deep, moderate, and shallow focus earthquakes
             > A map showing mostly shallow focus earthquakes, with a few moderate or deep ones, in a line 
             > A map showing shallow focus earthquakes  randomly distributed with no discernible lines
             > A map showing shallow focus earthquakes in well-defined lines--particularly if the area is located in the mid-ocean


* Make a list of all the places on the earth where water can be found.

* Construct a representation (e.g. sketch, drawing, concept map) of the hydrologic cycle showing reservoirs of water and the processes that move water between reservoirs.

* Define the term watershed, and tell how we can recognize the boundaries of a watershed by finding areas of high elevation.

*  Tell all the different pathways a drop of water could take after it enters the Chicago watershed.

Department of Earth Science | Northeastern Illinois University

© 2006 Laura L. Sanders.  Last updated November 7, 2006.