Answer 1:
When fault blocks move, there is usually one block
that goes up and another that goes down, and the
one that goes up becomes a mountain or mountain
range, while the one that goes down becomes a
valley. Erosion then sculpts the shape of the
fault blocks into the peaks and ridges you more
commonly think of when you think of mountains.
The fault blocks move in the first place due to
movements in the Earth's crust driven by plate
tectonics. For example, the North America plate is
moving west north-west from the Mid-Atlantic
Ridge, and the Pacific Plate is moving north
north-west from the East Pacific Rise. A few
million years ago, the part of the East Pacific
Rise of California got run over by the North
America plate, which means that the North America
Plate now meets the Pacific Plate directly,
instead of having another plate (namely the
Farallon Plate) in-between. Because the Pacific
Plate is moving northwest slightly faster than the
North America plate, the junction between the two
is sliding northward and stretching out western
North America. This sliding is what causes the San
Andreas Fault, and the stretching is what causes
the basin-and-range faulting that covers most of
Nevada. Due to a historical accident, the western
edge of the North America plate is not straight,
however, but zigs just north of the Santa Barbara
Channel. Thus, while the Pacific Plate is moving
north, it slams right into the North America
Plate, creating fault blocks that push up the
Santa Ynez Mountains and the rest of the
Transverse Ranges. The Sierra Nevada and Wasatch
mountains, meanwhile, are moving up because they
are being tilted as the valleys in Nevada fall
downward into the hole created by the stretching.
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