 The first phase of regional <unk> started 210 million years ago in the late Triassic and continued throughout the Jurassic to about 150 million years before present ( BP ) . Around the same time , the Nevadan orogeny built the Nevadan mountain range ( also called the Ancestral Sierra Nevada ) to a height of 15 @,@ 000 feet ( 4 @,@ 600 m ) . This was directly part of the creation of the Sierra Nevada Batholith , and the resulting rocks were mostly granitic in composition and emplaced about 6 miles ( 9 @.@ 7 km ) below the surface . The second major pluton emplacement phase lasted from about 120 million to 80 million years ago during the Cretaceous . This was part of the Sevier orogeny . 
