Transcript 6.4 Notes - Cloudfront.net

6.4 Notes
California Geology
The San Andreas Fault is a strike-slip
fault located at a transform boundary
Most of California
is on the North
American Plate.
However, a part
of the west coast
of California is on
the Pacific Plate.
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How were the Sierra Nevada Mountains
created in California if we live on a transform
boundary?
California used to have a big subduction zone
under it. The Farallon plate (an old oceanic
crust) subducted under the North American
Plate creating the Sierra Nevada Mountains.
After the Farallon Plate mostly subducted, the
Pacific Plate and the North American Plate
then touched creating a transform boundary.
The current Juan de Fuca plate is what is left
of the Farallon plate.
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Are the Sierra Nevada Mountains still
growing? Why or why not?
No, that particular mountain range is no longer
growing because now the Pacific plate and
the North America plate meet at a transform
boundary (not a convergent boundary). We
now have a lot of earthquakes in California
that we didn’t before because we are located
at a transform boundary.