Granite comes from the melting of continental crust. Usually it's oceanic crust that contains many fossils. Continental crust can only be melted at subduction zones along transverse fault lines. The closest active subduction zone to ground zero is just west of Northern California and it goes al the way up to Canada. Millions of years ago, California had a subduction zone too and the end result was the San Andreas Fault and the Juan de Fuca Plate which is being carried under the continental crust. This happens for two reasons. One, the oceanic crust of the Juan de Fuca is more dense as it has carried more weight due to water. And two, convection currents drive the process. See the diagram below for a more detailed explanation.
Granite, as you already know, can only be found in areas near active fault zone of large tectonic movements, such as the San Andreas Fault. Depending on how active the fault it, the granite can be jagged or smooth in some areas when unearthed. Granite not only looks nice and shiny when polished, but it also is extremely strong. This is because granite forms when melting continental crust, likely from the subduction of the Juan de Fuca plate under the Pacific Plate in Northern California to Washington State. This type of rock is called metamorphic because it is made by the melting of other rocks. Granite can reach the surface of the earth through large tectonic activities. The San Andreas Fault has then uplifted deposits of melted ocean crust to the surface. Granite is found quite frequently in the north west of the North American Continent. Because granite is made from lava or melting of continental crust, it is classified as igneous rock.
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1. Levitated Mass on the first line of your email.
2. Describe the texture AND color of the granite at this location.
3. Describe the weathering process of this rock. Is there any rusting or corrosion? If so, where do you see it and why is this occurring?
4. Because granite is an igneous rock, it has many different types of minerals inside of it. What is the most abundant mineral you see in this piece of granite?
5. What physical geologic differences can you see between the exposed parts of the rock (to the elements) verses under the rock? This will require you to go under the rock.
Works cited
http://graniteobjectspta.co.za/granite-formed/
https://legacy.etap.org/demo/grade4_science/lesson5/instruction2tutor.html
http://www.geography.hunter.cuny.edu/~tbw/soils.veg/lecture.outlines/soils.chap.1.2/soils.chap.1.2.htm
