PART I 

 THE LITHOSPHERE 



CHAPTER I 

 RELIEF FEATURES 



The surface of the earth includes the land and the sea. The 

 area of the sea is nearly three times that of the land, but the land 

 is of greater interest to man, because it is his home. 



The surface of the land is uneven. The lowest lands are below 

 the level of the sea, and the highest point of land (Mt. Everest in 

 the Himalaya Mountains) is between five and six miles above it. 

 The unevenness, or relief, of the land surface is therefore not far from 

 six miles. The .sea bottom is also uneven, and its relief is a little 

 greater than that of the land. Since the highest points of the land 

 are nearly six miles above the sea, and the lowest parts of the sea 

 bottom about six miles below, the relief of the surface of the lithosphere 

 is almost twelve miles. If the surface of the lithosphere were even, 

 the water of the ocean would cover the whole earth to the depth 

 of about 9,000 feet. 



RELIEF FEATURES OF THE FIRST ORDER 



If the high lands of the earth were planed down and their 

 material spread over the low lands so that all parts of the land had 

 the same height, the land would be a little less than half a mile above 

 the sea. If the sea bottom were made level, the depth of the water 

 would be about two and one-half miles. The continents are there- 

 fore nearly three miles higher, on the average, than the bottoms of 

 the ocean basins. The continents and the ocean basins are relief 

 features of the first order. 



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