CHAPTER IX 



MARINE DEPOSITS 



Many thousands of samples of deposits have 

 been obtained from the floor of the ocean, 

 from all depths and in all latitudes. These 

 have been carefully examined and compared, 

 with the result that we can now form a very- 

 good general idea of the composition and 

 distribution, both horizontally and with 

 regard to depth, of the various types. It is 

 true that the samples from the sounding 

 tube are usually small in quantity, but these 

 have very frequently been supplemented by 

 very large quantities from the dredge and 

 trawl. Our knowledge of these deposits is 

 limited to the upper layers, for the sounding- 

 tubes, trawls and dredges do not sink deeper 

 than three feet, and generally only a few 

 inches, into them. 



The rocks of the land-surfaces are continu- 

 ally undergoing disintegration through atmos- 

 pheric and other agencies. The products of 

 these weathering processes are ultimately 

 carried into the ocean by rivers and winds. 

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