22 



DRIFTING SAND. 



ie\x places on the summits oi the ridges i Tab. XIII ). Two 

 samples from this locality show a remarkably perfect 

 sorting, though one of them iiio. 58 i. which was taken 

 from a drifting cultivated field, carries the usual quantity 

 of fine grades present in drifting soils. 



It will be noticed that in all the.se samples of dune 

 sand, excepting the one collpr-ted l)y skimming the ridge 



Table XIII. Mechanical Corr position of Blown Sand from Henderson County. Ills. 





37 



38 







Length of 



diameter In 



mm. 



From a done no 



the biufl east of 



Carman. 



Prom a field 

 near Decorra. 



Average. 



16-8 











8-4 









4-2 









2-1 









1— J 



1.2 



.2 ■ 



.7 





^ 4 



5.4 



1.7 



3.5 





4 S 



84.6 ^H 



^1.4 ^H 



s3.0 



V 



i-iV 



8.6 1 



'•?.0 



.^.3 





1 1 



16 3 2 



.2 ^ 



5.0 



2.6 





^-sW 







2.0 



1.0 





64 12S 









lis 256 









of a ripple,, the maximum ingredient is fine sand. In one 

 instance ninety-two per cent consists of this gTade. whiln 

 in three cases it forms over eighty per cent of the bulk. 

 Wliere lowest it forms forty-five per cent, and it averages 

 sixty-five per cent in all the sand examined (Tab. XIV). 

 In three of the samples ninety per cent is distributed 

 among four grades: in twenty-two. among three grades; 

 and in thii-teen. between onlv two. Here also the admix- 



