Figure 6-9Earth’s Major Tectonic Plates (a) Earth’s surface is divided into a dozen or so rigid plates that move relative to one another. The boundaries of the plates are the scenes of violent seismic and geologic activity, such as earthquakes, volcanoes, rising mountain ranges, and sinking seafloors. The arrows indicate whether plates are moving apart (← →), together (→ ←), or sliding past one another (↑↓). (b) Rubbing of Two Plates. The San Andreas fault, running up the western coast of North America, formed because the Pacific plate is moving northwest along the North American plate. (c) Separation of Two Plates. The plates that carry Egypt and Saudi Arabia are moving apart, leaving the rift valley that contains the Red Sea. (d) Collision of Two Plates. The plates that carry India and China are colliding. As a result, the Himalayas are being thrust upward. In this photograph, taken by astronauts in 1968, Mount Everest is one of the snow-covered peaks near the center.