Premidterm Exploring the Oceans

The Earth is a water planet; (a)   percent of its surface is covered by vast tracts of oceans. Answer:

The Earth's structure consists of a dense iron-nickel core, a mantle rich in ______, ______, and silicon, and a thin outer crust of aluminum, silicon, and other elements. Answer:

(a)  

The Earth's interior is divided into three distinct layers: the crust, the mantle, and the (a)   . Answer:

The outermost shell of the Earth, the (a)   , is very thin in comparison with the deeper layers and consists of the rocks on which we build homes and from which we mine ores. Answer:

The composition of the biosphere consists largely of ______, ______, and oxygen compounds. Answer:

(a)  

The morphology of the ocean floor can be divided into three physiographic provinces: the (a)   , the deep-sea basins, and the midocean ridges. Answer:

The deep-sea bottom is not monotonously flat and featureless everywhere; parts of it are as uneven and rugged as the familiar mountain topography of the (a)   . Answer:

The distribution of water on Earth is dominated by its vast (a)   , which cover almost 71 percent of its surface. Answer:

The ocean contains about (a)   cubic kilometers of liquid water, an enormous quantity. Answer:

Water is an absolutely necessary ingredient for the development and sustenance of (a)   . Answer: