what plate is the sierra nevada mountains on
Sierra Nevada (U.S.) In the Cretaceous, a subduction zone formed at the edge of the continent.[20] This means that an oceanic plate started to dive beneath the North American plate. Magma formed through the subduction of the ancient Farallon Plate rose in plumes (plutons) deep underground, their combined mass forming what is called the Sierra Nevada batholith. These plutons formed at various times, from 115 Ma to 87 Ma.[21] The earlier plutons formed in the western half of the Sierra, while the later plutons formed in the eastern half of the Sierra.[18] By 66 Ma, the proto-Sierra Nevada had been worn down to a range of rolling low mountains, a few thousand feet high.
North American Plate On its western edge, the Farallon Plate has been subducting under the North American Plate since the Jurassic Period. The Farallon Plate has almost completely subducted beneath the western portion of the North American Plate leaving that part of the North American Plate in contact with the Pacific Plate as the San Andreas Fault. The Juan de Fuca, Explorer, Gorda, Rivera, Cocos and Nazca plates are remnants of the Farallon Plate.