Related: Earth's crust is peeling away under California The researchers found that ... broke off from an ancient tectonic ...

Even the oldest and most stable of lithospheric structures can’t withstand geologic machinations deep within the Earth.

To the west of the fault is the Pacific plate, which is moving northwest. To the east is the North American Plate, which is moving southeast. Los Angeles, located on the Pacific plate, is now 340 ...

The North American ... the North American craton causing the drips, and indeed that something turned out to be a "chunk of oceanic crust that broke off from an ancient tectonic plate called ...

The Farallon plate and the North American plate once formed a subduction zone along the continent's west coast, with the former sliding beneath the latter and recycling its material into the mantle.