Looking at this geologic map of California is very interesting. When you glance at Google Maps or Google Earth, you might notice that there are green areas and brown areas, but you really don't start to appreciate the geological diversity until you pull up that real geological map!
The number of different colors on that map really makes you realize how many types or rock and geological features are present, how many different ages of rock there are, and how incredibly close they can all be together.
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Screenshot of suspicious feature.
Geologic Map of California (2010).
Retrieved from maps.conservation.ca.gov |
After I looked at the map for a few minutes I noticed something; a big yellow valley with a little red dot in the middle. What could this be? As I zoomed in I noticed that there were many different types of rock that were literally ages apart, all smashed into this little round dot. Immediately I thought "Hmmm, I bet that is a volcano or something."
Sure enough, I pull up Google Earth and try to compare the two maps together until I can pinpoint the location and it was in fact an old, now inactive, volcano!
The volcano is called Sutter Buttes now. I only read a small amount about it, not because I don't want to learn more, but because I wanted to try to see what information I could infer from the maps without just reading it all.
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Closer screenshot of feature.
Geologic Map of California (2010).
Retrieved from maps.conservation.ca.gov |
I would like to know if this volcano arose due to the neighboring oceanic plate subducting under the North American continental plate. We have learned that the oceanic plate subducting will bring down some water along with it which will lower the melting point causing it to become more buoyant and rise to the surface, in this case as a volcano. As I look at the map, I notice that it makes sense too because it would put it right on line with more volcanoes that spread up the coast to Oregon, Washington and Canada.
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Basin between two mountain ranges.
Screenshot Retrieved from Google Earth. (2020) |
I would also like to ask, how are some of the rocks in this volcano so new, (mostly Quarternary rocks), while others in the same formation are Eocene and even as old as Cretaceous? I would guess a couple things. I think it could be that those older rocks were already there, and then later on, the intrusive igneous volcano cut it's way through it. This would demonstrate the principle of cross-cutting relationships because in order for the igneous intrusions to cut through the older rock, the older rock had to exist in the first place. I do find it interesting that portions of the Cretaceous rock are exposed and other parts are Quarternary. Could this be due to erosion only cutting through parts of the rock? (so far that is).
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Sutter Buttes
Screenshot Retrieved from Google Earth. (2020). |
Did continental uplift create the ranges on either side of this basin? I would think that all these older rocks would have been in place first, then more subduction of the oceanic plate started to cause the mountain ranges to form as plutons underground. This could have been followed by erosion which exposed them.
Something else I would like to know is how this basin formed in the first place? I would naturally think that a basin like this would be formed by tensional forces spreading the crust apart. I see a lot of farm land here which makes me assume that the valley is loaded with sediment deposits from the surrounding mountain ranges runoff. I would like to ask for more detailed fault information in the region so I can see if tensional forces caused normal faulting.
I have more questions I would ask but I think this post is too long as it is. I will research more after I post this.
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