The Oceans

Oceans play a major role in the earth’s natural processes because of their production and control of climate, supplying moisture to the atmosphere and providing a vast climatic regulator. They form the ultimate site of deposition of almost all sediment and are the home of many living species of animals and plants. The oceans cover over 70 percent of the earth’s surface. The continents are surrounded by shallow, gently sloping continental shelves. The average ocean depth is almost three miles, but trenches, up to 36,000 feet deep, are found in places. Although much of the deep ocean floor is a flat plain, some parts are more mountainous than the mountain regions of dry land. A worldwide system of midoceanic ridges includes submarine mountain chains, marked by intense vulcanism and earthquake activity, and offset by transform faults. They are the sites of the formation of new crustal rocks. There are also many volcanic islands, including many submerged below sea level.

Text A.This Ocean is the second largest ocean on Earth, but it is only half the size of the biggest one. Its coastal waters include the North, Baltic, and Mediterranean seas in the east, and the Gulf of St. Lawrence, Gulf of Mexico, and Caribbean and Sargasso seas in the west.

Text B. The main part of the North Pole is the frozen Ocean. The land areas include the northernmost parts of Europe, Asia, and North America. The polar ice cap also extends over Greenland. To the south of the ocean lie the regions, which are almost as cold in winter but have warmer summers. The coldest region is northeast Siberia.

Text C. The third largest of the world’s oceans, it washes the continents of Africa, Asia, Australia, and Antarctica. Most of the ocean and its many, mainly small, rocky or coral islands have a tropical climate, free from extremes of temperature. The main winds affecting climate are the dry and wet seasonal monsoons, and westerly winds which can bring violent storms. The ocean has been an important trade route since ancient times. The island groups were first settled by people from India, Arabia, and Africa.

Text D.This ocean is the largest and deepest in the world, covering a third of the Earth’s surface. The deepest point of the ocean is the Mariana Trench, over 36,100 feet (11,000 meters) down. It has thousands of islands. Some are the tops of volcanic mountains. Others are coral reefs, many resting on the peaks of submarine mountains.