The Pacific Ocean Area: 63.78 million sq miles (165.2 million km²);
Mean depth: 14,042' (4,280 m)

To the west of the great Plain lie the Rocky Mountains, “the backbone of the continent. These majestic mountains stretch an the way from Mexico to the Arctic and form what is known as Continental David, or Great David, the most important watershed on the continent The Rockies are more than twice as hi^i as the Appalachians and hi^i enough to receive more precipitation than the surrounding plains and plateaus. Consequently, they are mostly forested. The striking and varied scenery of the Rockies has given rise to the establishment of many national parks here. The most famous one is the Yellowstone National Park which covcrs an area of about 9，000 square kilometers. It is in the northwest comer of Wyoming, but also takes up part of Montana and Idaho. Yellowstone has about 3，000 geysers and hoc springs. It also has mud volcanoes, fossil forests, and volcanic glass.

The Pacific Ocean Body of salt water extending from the Antarctic region in the south to the Arctic in the north and lying between the continents of Asia and Australia on the west