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PHYSIOGRAPHY 



Some of its movements, such as waves, may be 

 seen and studied from the shore, but others, such 

 as the currents (streams in the ocean), are less 

 readily seen. 



The most that is known of the depth of the 

 ocean, its temperature, its life, and the material 

 and topography of its bottom, has become known 

 through exploring expeditions which have been 

 sent out from time to time to study these things. 

 The expeditions which have done most have been 

 fitted out by governments in some cases, and by 

 societies or individuals in others. 



Distribution of the ocean waters. The distri- 

 bution of the ocean water has been outlined in a 

 general way in connection with the land (p. 4). 

 The ocean encircles the earth in latitude 60 S., 

 and the waters south of latitude 40 S. are some- 

 times called the Southern Ocean. From it the 

 Atlantic, the Pacific, and the Indian oceans extend 

 northward. In the northern hemisphere the land 

 makes an almost complete circuit in latitude 60 to 

 70, whence it extends southward in two great 

 arms. North of latitude 70 or so, lies the Arctic 

 Ocean. 



Depth. The average depth of the oceans is 

 about two and one-half miles, or between 12,000 

 and 13,000 feet. The Pacific is the deepest ocean, 

 and its greatest known depth of ocean water is 

 nearly six miles, a trifle more than the height of the 

 highest mountain above the sea. There are many 

 places where the depth of the ocean exceeds four 

 miles, and the area of very deep water is much 

 greater than the area of very high land. The 

 areas which are far below the average depth of 

 the ocean are often known as deeps. 



The greatest depth of water known, 31,614 feet, 

 is in the Northern Pacific, near the Ladrone Islands. 



