KTE Assignment:

sAMPLE OF KTE SPRING 08

Wendy Conway
February 28, 2008
Geology 110
KTE #1 Assignment

Key Term #1: Ultramafic
            Ultramafic is a classification of igneous rock.  Ultramafic rocks are very rare on earth’s surface and are almost always composed of the mineral ferromagnesian, which takes the form of either olivine or pyroxene.  The silica content of this category is very low, about 45%.  In addition, ultramafic rocks are believed to compose the majority of the earth’s crust. (Lutgen & Tarbuck 64). 
            Research scientist N.L. Bowen, studied the reaction series of the various categories of igneous rocks and discovered that the ultramafic rocks have the highest melting temperature, around 1200 degrees Celsius.  It was also discovered that ultramafic rocks also have the highest cooling temperature.  For instance, because the ferromagnesian mineral olivine is an ultramafic rock, it will begin to crystallize first in a magma flow. (71)
            Below is a chart of Bowen’s Reaction Series taken from: http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/bowen.html.
            This chart illustrates the relationship between melting temperatures and igneous rock type.  With olivine being an example of an ultramafic rock with a high melting temperature as compares to quartz, a felsic rock with a much lower melting temperature.
 
           

Below is a picture I took of olivine sand.  This sand was taken from Green Sands Beach at the south tip of the Big Island in the State of Hawaii.  The sand on this beach is the result of a past volcanic eruption that contained high amounts of olivine.  When the lava flowed out from the volcano and hit the cool water of the Pacific Ocean, the olivine cooled and shattered.  Over time the olivine was further broken down into granulized sand partials and washed up onto the shores of the very small Green Sands Beach.

This picture was taken on February 1, 2008 in my backyard.

Key Term #2: Volcanoes
            Volcanoes are openings on the surface of the earth that allow lava, gas and ash to escape.  Volcanoes are the result of active plate tectonics, either converging, or diverging plate boundaries.  The mid-Atlantic ridge is an example of an expanding plate boundary, where as the western coasts of the Americas is an example of converging plate boundaries. (http://en.wikipedia.org/wiki/Volcano) 
The formation of igneous rocks is due to volcanic activity.  The cooling of magma or lava results in the formation of igneous rock.
The image below illustrates an oceanic plate sinking under a continental plate, such as is the case with the western Americas.  The pressures created by the converging plates raise the continental plate forming mountains and volcanoes. 

http://en.wikipedia.org/wiki/Convergent_boundary

            In the mid-Atlantic the oceanic plates are separating from one another.  In this case the opening in the crust allows magma to flow to the surface, forming volcanoes as illustrated below.
wrgis.wr.usgs.gov/ parks/pltec/diverge.html
 

Below are a few pictures I took in the Mojave Desert.  

1] This is the Cima volcano and an old lava flow. 

Photo taken on Feb 7, 2008 in the Mojave Desert.

2] This is a picture of me inside a lava tube.

Photo taken on Feb 7, 2008 in the Mojave Desert.

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