PLATE XXXIII. 

 Pig. a. 



(Sp. No. 32713. AVithout analyzer, x 35.) 



■Water-tleposited sand. This volcanic sand consists chiefly of feldspar and hornblende. The 

 rounded nature of the feldspar grains is readily seen. Under the microscope some of these show 

 secondary enlargements. The hornhlende is in irregular areas, and is presumed to be secondary after 

 fragments of augite. (Described, p. 144.) 



Pig. B. 



(Sp. No. 32711. AVithout analyzer, x 17.) 



Water-deposited volcanic sediment. This illustration shows very clearly the gradation from 

 the medium-grained volcanic sand in the lower portion of the section, through the finer-grained mate- 

 rial, to the very fine grained dust. The very fine grained material was deposited following the con- 

 tours of a large pebble, which is shown in the upper portion of the figure. The fragments of this 

 sand consist chiefly of basalt. There are some which were probably feldspar. (Described, p. 144.) 



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