9781422277539

This sonar-created map of the ocean floor shows deep trenches, plateaus, and volcanic mountains in the western Pacific Ocean, an area of intense volcanic activity.

with almost a mile to spare. The sheer volume of water in the world’s oceans is enormous—it has been estimated at over 240 million cubic miles (a billion km 3 ). The Active Ocean Floor The ocean floor is made from a special kind of rock, called basalt . It is very heavy and black, and quite different from the

What Are Oceans?

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