East Coast vs. West Coast
This past weekend I went to the Jersey shore (not the regrettable tattoo and binge drinking part). Looking at maps of the coastline there and all the way down the eastern seaboard, down to Florida, made me think about the differences between the East Coast and the West Coast. Not just the good summer tomatoes vs. readily available avocados part, or hurricanes and nor’easters vs. earthquakes, or Minor Threat vs. Black Flag. But the shoreline itself. Why do the East Coast and the Southeast have barrier islands?
The Georgia coast:
And the West Coast doesn’t?
I don’t know.
Not that it’s surprising that they look different. They’re really far away from each other.
As big as California’s shoreline is, there are a lot of rocks just off the coast, but not that many islands. (Geologists, please forgive me for being really really basic here. If I get anything wrong, or you want to explain in more detail, please have at it!) California’s eight Channel Islands in Southern California were formed by tectonic forces, volcanic activity, and sedimentary deposits. The four northern Channel Islands are like the top of a mountain ridge sticking out of the ocean. They were never attached to the mainland.
Ano Nuevo Island between Santa Cruz and Half Moon Bay was the tip of a peninsula until relatively recently; Spanish explorers did not record it as an island when they were here. The Farallones, off of San Francisco, are made of the same magma as the Sierra Nevada. And the islands in the San Francisco Bay are hilltops that remained above water level after the mouth of the Sacramento and San Joaquin Rivers was flooded.
Back to Georgia (courtesy of NOAA).
The barrier islands on the Atlantic, at least the ones on the Georgia coast, which are the ones I’ve been reading about (and the ones I grew up visiting) are remnants from a much lower sea level. As the sea rose, it inundated low-lying land behind the islands, creating salt marshes and the intercoastal waterway.
Also, one last thing, because I mentioned New Jersey and growing up: ECFU (in case you are in an office without headphones or you are 12, this video has language that we would not use in public radio).
The Natural History of the Islands of California was helpful for half of this post. The Georgia stuff I scrounged up online.