Forsyth lab/Brown University

An ancient, "lost" tectonic plate that disappeared under North America millions of years ago may have been found again. The Isabella anomaly (IA, above), is at the same depth (ca. 100 km) as other fragments of the Farallon plate under Oregon and Washington, is on a line with fragments off the California coast, and has a similar seismic tomography signature.

A tectonic plate that disappeared millions of years ago has turned up in Central California and Mexico.

New research from Brown University found that part of the Baja region of Mexico and part of central California near the Sierra Nevada mountains sit upon slabs of this long-lost plate. It's a big breakthrough in how we think about California's 100-million-year-old geology.

Under California: An ancient tectonic plate

Sean Gulick, a geophysicist from the University of Texas at Austin, gives Take Two a little lesson in plate tectonics.