16 



DRIFTING SAXD. 



tertinry bed.<. Their extensive development show;^ that 

 the wifld has been at work here for some considerable 

 time. The sand is correspondingly uniform, and rock 

 fragments of either extreme size are absent (Tab. Vr). ( )ne 

 of the analyses exhibits the mechanical composition of a 



single thin lamina in the dune (no. 34). evidentlv laid 



- • • . "-■ 



down under a uniform wind velor-itv. It is interestino- as 



Table VI. Mjchanical Composition of Dune Sand from Rice County. Kans. 





33 



33 



34 





Len^h of 

 Diameter in 



mm. 



From the EroDt 

 j slope of a dnne. 



Ftom the rear 

 elope of a done. 



From the fpoot 

 elope of a dune 

 (a sipgle Heatn) 



ATerage. 



16-8 











8-^ 



1 









4-2 



2 







tr. ' 



2-1 



.0 









1-i 



6.2 1 



6.6 1 



1.5 



III 



i-1- 



34.8 B 



28.2 h 



10.0 1 



24.3 I 



i-i 



57.8 ■ 



61.2 li 



83.0 ^H 



67.3 Hi 



i-^ 



.&\ 



2.7 r 



4.5 r^ 



2.6 n 



iHr-^ 





.1 1 





tl-. ' 



A-st 











1 1 



64 138 











xb-^ 











indicating, when compared with the other analyses, the 

 range of variation in the coai'seness of the sand due to 

 differences in the velor-itv of th^ wind. Evidentlv this is 

 not very great. 



At Folly's Cove in Massachusetts some beach sand is 

 driven inland by the winds. The absence of fine particles 

 in tMs sand is no doubt partly due to washing on the 

 beach (Tab. VIIi, 



