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Geology/Geology take home test


which of the following factors is most important for controlling the composition (or mineral content) of a metamorphic rock?
a. composition of potolith
b. temperature
c. pressure
d. time
e. tectonic forces



First, the first one should be Protolith, which is the original rock before metamorphism.

Let me ask you a question.  If you have a bowl of apples, can you turn it into pineapple cake by mashing it up, or heating it, or leaving it in the oven a long time, or squashing it between two cars?

If you answered no, you are right.  So, you cannot make marble which is metamorphosed limestone from the protolith sandstone right, because it is quartz.

Nor can you make slate from the protolith, limestone because it is calcium carbonate and not silicate clays.

Get it?  You cannot make one thing if you start with the raw materials for something else.
So if you have the minerals in one rock, the Protolith, just by heating it, mashing it up, letting it sit for a long time or crunching it up with continental drift, you cannot expect it to change into a completely different rock requiring different minerals to make.

The correct answer is a.  


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Keith Patton


I can answer questions concerning physical and historical geology, environmental geology/hydrology, environmental consulting, remote sensing/aerial photo interpretation, G&G computer applications, petroleum exploration, drilling, geochemistry, geochemical and microbiological prospecting, 3D reservoir modeling, computer mapping and drilling.I am not a geophysicist.


I have 24 years experience split between the petroleum and environmental industries. I have served as an expert witness in remote sensing, developmental geologist, exploration geologist, enviromental project manager, and subject matter expert in geology and geophysical software development.

American Association of Petroleum Geologists
American Association of Photogrammetrists and Remote Sensing

Bachelor and Master of Science
Registered Geologist in State of Texas

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