Although Planet Earth itself is 4.5 billion years old, the oldest rocks in San Diego are relatively young only at the age of 150 million years. This should not come as a surprise, since the reader understands all the fault lines and, as a result, earthquakes in the area. Being on the edge of the continent, the movement of the tectonic tile caused a large magma to our area, so our area is reliably young.
Let us now skip ahead for millions of years, since most of the topology of the area has been formed over the past 2.5 million years. There are two main forces in the region.
- First, sea levels have changed hundreds of feet during this time, when glaciers came and went for thousands of years. The point is not that our region had ice cover, but there was a lot of water in the glaciers that hit the sea levels. It is easy to recognize old sea floors in our area, looking at flat areas.
- Secondly, the area around San Diego is growing as a result of tectonic activity. In fact, west of I-5 near San Diego, the earth is growing at a speed of 18 inches every thousand years.
If we looked at San Diego just 100,000 years ago, most of it was under water. Only the summits of Point Loma and Mount Soledad would have been visible. However, as a result of sea level and tectonic forces, water was able to cut channels through the earth, which led to the topology that you see in the area today.
For more current events, here are some interesting points:
- The North Island and Coronado Island were once separate pieces of land. This is due to the fact that the fault line works exactly between them. The fleet has filled this area, but it is still geologically active.
- Mission Bay, as you expect, is quite young at about 10,000 years old and was shaped by the action of ocean waves besieging sand.
- "Silver Coast" is a natural phenomenon caused by ocean waves coming from the south, and the deposition of sand.
Of course, the San Diego story may fill volumes, but I hope you will have a little better idea of this area, which many of us call home.
