The Sierra Nevada Mountains & Yosemite National Park: Road Log Geology Paperback – July 11, 2023

The Sierra Nevada Batholith was emplaced in the western margin of the North American plate presumably as a consequence of convergence of the North American plate with plates of the Pacific Ocean. Events that occurred along an eastward dipping subduction zone such as shifts in its position, changes in the angle of dip, the arrival of exotic terranes, and changes in the rate of subduction probably caused the episodic shifts in the locus of plutonism. No evidence has been recognized that indicates any intrusion was emplaced during a major compressional regional tectonic event, but some intrusions were effected by regional deformation after they were emplaced. Much of the deformation in the country rocks within and adjacent to the batholith was caused by forcible intrusion of plutonic rocks rather than by compressive regional deformation during the Nevada orogeny.Metamorphic rocks of the western Sierra Nevada near the Merced River are of Jurassic and Paleozoic age. They are on the west limb of a faulted synclinorium, the central part of which is occupied by the Sierra Nevada batholith. Parts of the eastern limb are preserved in the eastern part of the Sierra Nevada and in the White and Inyo Mountains still farther east. The metamorphic rocks strike northwest reflected in in map pattern of lithologic units. Nearly everywhere, they dip steeply eastward or are nearly vertical. The metamorphic rocks are divided into three structural blocks by the Melones and Bear Mountain fault zones. The structure within each block is generally homoclinal with younger beds to the east, but the gross distribution in the metamorphic belt as a whole has been reversed by fault movement. The youngest metamorphic rocks are in the western fault block and the oldest in the eastern fault block. Dominant strike slip movement along the Bear Mountains and Melones fault zones is suggested by steeply plunging minor folds and lineations within the zones. The stratigraphic separation along the Melones fault zone near the Merced River is at least 10 miles and the stratigraphic separation along the Bear Mountains fault zone farther north is 3 miles. Because the dihedral angle between the bedding and faults is small, the net slip along the fault zones must be much greater the the stratigraphic separations.Chapter 1 presents and introduction to the Sierra Nevada Batholith. Chapter 2 summarizes the pre-Tertiary geology of the western Sierra Nevada metamorphic belt. Chapter 3 begins the road log from El Portal California to Yosemite Valley. Chapter 4 provides an introduction to the geomorphology of Yosemite Valley and road log through Yosemite Valley. Chapter 5 discusses the granite geology of Yosemite Valley. Chapter 6 contains the road log for Big Oak Flat Road. Chapter 7 contains the road log for Tioga Pass Road. Chapter 8 contains the road log for Wawona Road north of Glacier Point Road. Chapter 9 is the road log for Glacier Point Road. Chapter 10 completes the road log for Wawona Road south of Glacier Point Road. Read more