BATHYAL DEPOSITS 



669 



Table of Analyses of Muds of Terrigenous and Volcanic 



Origin. 



erally has a red or brown color, due to iron oxide or hydrate, and 

 when dried its color is gray or brown from the oxidation of its con- 

 tained iron sulphides. Pure clay often constitutes only a small pro- 

 portion of this mud (though ranging from 16 to 97 per cent.), and 

 the lime content may be as high as 35 per cent. Quartz is a char- 

 acteristic constituent. This is the type of mud which has in the past 

 given rise to most of the marine shales and slates. 



The Red Mud. This is much more restricted in its distribution 

 than either the blue or green. It is found opposite the mouths of 

 tropical rivers, such as the Amazon and the Yang-tze-Kiang, and is 

 derived from the red laterite or residual soil of the tropical coun- 

 tries. Its percentage of pure clay varies from 28 to 68, and its 

 lime content varies from 6 to 60 per cent. ; glauconite is absent, but 

 quartz is characteristic. The red mud closely resembles the red mud 

 of the deep sea, which has, however, a different origin, being proba- 

 bly in large part the product of decay of volcanic material which 

 has settled to this depth. ]\Iuds of this kind may easily preserve an 



