Final answer:
The San Andreas Fault in California is a transform fault boundary between the Pacific Plate and the North American Plate, marked by a valley and known for causing major earthquakes.
Step-by-step explanation:
The San Andreas Fault is a transform fault boundary between the Pacific Plate and the North American Plate. This fault line runs from the Gulf of California to the Pacific Ocean northwest of San Francisco. The Pacific Plate, to the west of the fault, moves northward while the North American Plate moves southward. The major cities of Los Angeles and San Diego, which are on the Pacific Plate, are therefore moving in a northerly direction relative to San Francisco, which is on the North American Plate. The San Andreas Fault is marked by a valley and is known for producing major earthquakes due to the sliding motion of the plates.