Week 6 - Geological Interpretations California - Baker Beach

Credit: https://maps.conservation.ca.gov/

For this week's travel journal, I will go to the state of California to examine the region's fascinating geology.  Being located closest to one of the most active fault zones in the world there is bound to be much to discover.

First using the Department of Conservation's website, I was able to pick a region that looked like it had a little bit of everything going on.  At a Macro level, this is a geologic image of the region that surrounds San Fransisco.  I hopped in my favorite airplane, donned appropriate PPE to be out in public and set off for my destination.  What we can see to the left is a pretty interesting example of a varied geologic sample.


All the way to the left of the image is the San Andreas fault.  This area of the state has everything from faults, and folds to different compositions of rocks, from all different time periods.  The large purple section labeled um are mesozoic era ultarmafic rocks, while the section marked Ku are sandstone and shale from the cretaceous.  Realizing that I can only cover so much ground, I decided to focus in on the baker beach region of this part of the state.

https://maps.conservation.ca.gov/

When I arrived at Baker Beach i was greeted by a wide valley, with a view of the Pacific Ocean.  From the Beach I could see some large rocks that had broken the surface.  In order to gain more insight into the geologic history of this beach region.  To assist in my analysis I would need to understand:

1) The age and composition of the rocks sticking out of the water that I can see from the beach (see photo below).  This would allow me to figure out how old the surrounding outcrops of rocks were, and if the composition of the rocks were continental or oceanic in crustal nature.  That would allow me to understand how this part of the State came into being.
2)  I would want to understand the composition, of the rocks in the right frame of the picture.  What type of Rocks are they?  Are they mafic?  Basaltic?  What sort of intrustions run between them?  This would tell me not only the age of the rocks, but how they formed.  Evidence of magmatic intrusions, that were cross cutting the main formation would tell me if the land had a major volcanic event, and would allow me to see when that happened and date the surrounding rocks appropriately
3) Finally, I would want a full particle analysis of the sand, and any evidence of marine life within.  This would tell me a great deal about what sort of creatures lived in the area, and perhaps allow me to specifically date the area by determining the age of any such marine life.

https://www.californiabeaches.com/beach/north-baker-beach/

After submitting my requests to the California Geological survey, I jumped into my trusty airplane, and headed back to Pittsburgh, immediately regretting leaving a beach.

Sources:
https://www.californiabeaches.com/beach/north-baker-beach/https://maps.conservation.ca.gov/cgs/gmc/