Week 6 - David Clark - San Diego County - California

My brother moved from San Diego around 4 year ago. His departure was unfortunate, as I loved to visit him and his wife! Wanting to leave quarantine, my daughter and I constructed a rudimentary time machine from twine, sticks, and plutonium rods we had laying around. We went back to March, 2014. Times were good then, with thoughts of quarantine the furthest thing from peoples minds. We drove down to San Diego to visit my brother and decided to do some geological research. It is common practice on our vacations to always check the geological maps to see what we might discover!

We pulled this photo above showing Sand Diego County in the dark black square, with greater California and Mexico around it. What immediately struck us was the many fault lines in the Pacific Ocean. The first question we had was what type of faults are these? Normal faults? Reverse Faults? Perhaps Strike-slip faults from plates moving past one another? The next question we had was where are the tectonic plate boundaries? Are these faults from the Continental Pacific Plate? If so, how is the Pacific Plate moving to create these faults? We decided to investigate further, so we headed towards the sea.

The picture above is what we saw when we got there! Seems like we have some great lateral continuity from the rocks above. Which makes us think that whatever faults are out in the ocean, they are not applying pressure here, or we would see compression evidence in the rocks from folding. It makes us think that the faults in the ocean perhaps are Strike-slip faults? We can see from above that we have some fossils of deep sea fans from the Cretaceous Age, what does that tell us? To the archives! We dug up (pun intended) the map below of what the world look liked during the Late Cretaceous period. We can see the it appears San Diego county wasn't even a part of the U.S.! We must have been shifted over the shallow sea via tectonic forces to the east over millions of years. Is this the process that created the Rocky Mountains? How does this factor into our faults in the ocean?

Still not satisfied, we returned to the archives, to see what the world looked during the Quaternary Period. The image below we pulled from the archives and yes, it appears over the millions of years the sea receded, and the land moved in.We know this from the Quaternary fossils above the Cretaceous fossils and the fact that we are living in the present day! As we hopped back in our time machine, we were still wondering about the faults. We decided if we were to gain more information, we would have to take a vessel out above the faults, to do some on-site surveying.We would want to know the rock types around the faults, perhaps the temperature of the water around the faults, and finally, and measurements of motion from each side of the faults. With that information, we could piece together exactly how the faults are moving, the faults types, and any danger associated with the faults.