Death Valley, one of the hottest places in the world, is the centerpiece of the Death Valley National Park in Eastern California. Death Valley was formed as a part of a graben. To the east of the San Andreas Fault System (SAFS) lies a tectonically active region called the Eastern California Shear Zone (ECSZ). The SAFS is the biggest indicator of activity between the Pacific and North American plates, but the ECSZ contributes 10-14 mm/year of movement along three fault zones: the Death Valley Fault Zone, the Panamint Valley – Hunter Mountain – Saline Valley Fault Zone, and the Owens Valley Fault Zone. We are most concerned with the Death Valley Fault Zone, a zone composed of right-lateral strike-slip faults and normal faults.
These plates are moving in some directions that I don’t know yet, but I’ll be sure to look that up after I write up the next couple paragraphs. Baja California, as it turns out, is not a cute, colloquial term for the lower section of California. It is literally a land mass underneath the state of California and a state of Mexico. You can imagine my confusion when trying to find a Gulf of California when looking at a map of the American state, but the Gulf of California sits in between Baja California and the rest of the Mexico mainland. Although Baja California is located miles off the rest of Mexico today, 5 million years ago, Baja California began to break away from Mexico and the rest of the North American tectonic plate. So how is it that it is a separate landmass today? You guessed it: plate tectonics!
Underneath the land masses we see on a map, there lies a mid-ocean ridge system called the East Pacific Rise. The East Pacific Rise is a system of underwater mountains that ranges from Antarctica to the Pacific Ocean and the northernmost portion of this range is known as the Gulf of California Rift Zone. Mid-ocean ridges develop as an effect of plate boundaries: the North American and Pacific tectonic plates want nothing to do with each other and are slowly, but surely, being moved away from the other as a part of divergent boundary. As these zones become active on the ocean ridge systems, divergent boundaries begin to produce rifts, zones where the lithosphere is literally being pulled apart!
A phenomenon called seafloor spreading is the main culprit of the movement: magma rises from the ocean ridge systems and cools on either side of the ridge. This is also a major feature of a rift system: lithosphere is pulled apart and new crust is created. Over time, this creates new oceanic crust and lithosphere. The result? Baja California has transferred from the North American plate to the Pacific plate and the land is opening like a pair of breakaway track pants.
If we examine some evidence, we’ll find plenty of events pointing to the eventual separation of some of California from the rest of the North American plate. Firstly, Baja California and some parts of coastal California are included in the small percentage of continental crust on the Pacific plate. If Baja California is being slowly pushed away from Mexico, we can expect that some parts of California will do the same and be pushed away from the North American plate. The Gulf of California will extend upward and Death Valley may end up near coastal in the new plate configuration.
