Sierra Nevada-Great Valley Block
Encyclopedia
The Sierra Nevada-Great Valley Block (SVGV) is a section of the earth's crust in California
encompassing most of the region east of the Great Valley fault system which runs along the eastern foot of the Coast Ranges, and west of the Sierra Nevada Fault
which runs along the foot of the Sierra Nevada
's eastern scarp. To the south, the block is bounded by the Garlock Fault
. The northern bound is not well defined at present, but generally runs along a line extending across the northern Sacramento Valley
.
The SNGV has been found to behave like a rigid body relative to the North American Plate
to which it is somewhat loosely attached. The block moves in a northwest direction while the rest of the North American Plate is moving in a southwest direction. In far northern California, this produces a zone of convergence which has resulted in the compressive uplift of the Coast Ranges.
At its core, the SNGV block consists primarily of the Sierra Nevada batholith
which has been tilted westward like a large trapdoor with its "hinge" lying deep beneath the sediments which fill California's Central Valley. This tilt is attributed to the buoyancy of the eastern part of the block due to the greater subterranean heat associated with the tectonics of the adjacent Great Basin
, compounded by the weight of sediments accumulating over the western portion of the block.
A major feature of the block clearly visible from space and on topographical maps is the Kern Canyon Fault
which is regarded as a fracture resulting from differences in the stresses affecting the southern section of the block.
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
encompassing most of the region east of the Great Valley fault system which runs along the eastern foot of the Coast Ranges, and west of the Sierra Nevada Fault
Sierra Nevada Fault
The Sierra Nevada Fault is a normal seismic fault along the eastern edge of the Sierra Nevada mountain block in California. It also demarcates the western margin of the Basin and Range geologic province. Activity on this fault is responsible for the continuing uplift of the Sierra Nevada. ...
which runs along the foot of the Sierra Nevada
Sierra Nevada (US)
The Sierra Nevada is a mountain range in the U.S. states of California and Nevada, between the California Central Valley and the Basin and Range Province. The Sierra runs north-to-south, and is approximately across east-to-west...
's eastern scarp. To the south, the block is bounded by the Garlock Fault
Garlock Fault
The Garlock Fault is a left-lateral strike-slip fault running approximately northeast-southwest in the Mojave Desert of southern California. It runs for much of its length along the southern base of the Tehachapi Mountains...
. The northern bound is not well defined at present, but generally runs along a line extending across the northern Sacramento Valley
Sacramento Valley
The Sacramento Valley is the portion of the California Central Valley that lies to the north of the San Joaquin-Sacramento Delta in the U.S. state of California. It encompasses all or parts of ten counties.-Geography:...
.
The SNGV has been found to behave like a rigid body relative to the North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
to which it is somewhat loosely attached. The block moves in a northwest direction while the rest of the North American Plate is moving in a southwest direction. In far northern California, this produces a zone of convergence which has resulted in the compressive uplift of the Coast Ranges.
At its core, the SNGV block consists primarily of the Sierra Nevada batholith
Sierra Nevada Batholith
The Sierra Nevada Batholith is a large batholith which forms the core of the Sierra Nevada mountain range in California, USA, exposed at the surface as granite....
which has been tilted westward like a large trapdoor with its "hinge" lying deep beneath the sediments which fill California's Central Valley. This tilt is attributed to the buoyancy of the eastern part of the block due to the greater subterranean heat associated with the tectonics of the adjacent Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...
, compounded by the weight of sediments accumulating over the western portion of the block.
A major feature of the block clearly visible from space and on topographical maps is the Kern Canyon Fault
Kern Canyon Fault
The Kern Canyon Fault is a geological fault which runs the length of Kern Canyon in the southern Sierra Nevada mountains in California.The fault was once considered inactive, but recent studies show the contrary...
which is regarded as a fracture resulting from differences in the stresses affecting the southern section of the block.