What explains the San Francisco Bay?
When you look at the California coastline, it is mostly a run-of-the-mill, kinda "smooth" coastline. Except in San Francisco, where there is an important intrusion of water going inland. It even cuts the coastline in two, to the point the Golden Gates bridge had to be constructed. Nowhere else on the Californian coast we can see this kind of feature, except maybe in Eureka, with Arcata and Humboldt Bay. What explains this? Is the answer, again, glaciers?