the Pacific and North American plates grind past each other, sometimes with disastrous
consequences.
Figure 6.29: At the San Andreas Fault in California, the Pacific Plate is sliding northeast
relative to the North American plate, which is moving southwest. At the northern end of
the picture, the transform boundary turns into a subduction zone. ( 12 )
California is very geologically active. A transform plate boundary creates the San Andreas
Fault. A convergent plate boundary between an oceanic plate and a continental plate creates
the Cascades volcanoes. Just offshore, the Juan de Fuca ridge is subducting beneath the
North American plate at a divergent plate boundary.