Chapter 29, Problem 19RQ

To determine

The formation San Andres fault.

Answer to Problem 19RQ

The formation San Andres fault occurred due to joining of the plate of pacific and North America plates.

Explanation of Solution

The third and final phase of Pangaea’s breakup took place in the Cenozoic Era. This led North America and Greenland to split away from continents. In the late Mesozoic era, collision began the formation of the Sierra Nevada and Andes Mountains that continued till Cenozoic. A mid-ocean ridge was formed in the Pacific Ocean, known as the pacific ridge system. The pacific ridge system's collision with the westward-moving North American plate, which took place approximately 30 million years ago, gave birth to the San Andres fault form. If San Andreas is looked from outer space, it will look similar to a long, narrow valley through which this can be easily concluded that where the plates meet with the pacific plates.

Conclusion:

Therefore, the formation San Andres fault occurred due to joining of the plate of pacific and North America plates.