Originally Posted by TMonk

I was actually a geology major before switching to chemistry. Don't ask me for more details b/c I don't remember much. I think I recall the oldest crust being in the Canadian shield leading into Hudson bay. The east coast of the US is also on the North American tectonic plate, and there isn't much volcanic activity there, so yeah it's also quite old. Maybe that's why it's so boring out there compared to the Best Coast? IDK.

Fun Fact - coastal southern and central CA is actually on the Pacific Plate. The dividing fault is called the San Andreas and is very, very active. It's where we get our earthquake reputation from. But TBH, the earthquakes are way less problematic than fire - an omnipresent threat out here.