I.EE SAND. 



27 



LEE SAND. 



We have now to see what becomes of the rook frag- 

 ments that are finer than the maximum grade of the dune 

 sand, a small part of which onlj^ are retained in the drifts. 

 Right in the front of the dune drift, and confluent with it, 

 there is generally a smaller i-ippleless drift or liench of 



Table XVI. Mechanical Composition of Sand tal<en in the Lee of Sand Dunes In Rice co., Kansas. 



Letigth 



of diameter 



io mm. 



Averaj^c of 

 the duoe sand. 



Lee drift Hund. 



From six feet in 



front of tbe lee 



drift. 



6G 



From 15 feet in 



front of tlie lee 



drift. 



67 



From 24 feet in 



front of ttie iee 



drift 



16-8 



8—4 

 4—2 

 2-1 

 1— i 



1 t 



1 1 



4 S 



1 1 



5 IT 



1 1 



TT 32" 



1 L 



^? ¥4 



1 1 



1 1 



T2"g ■JTir 



4.7 

 24.3 

 67.3 



2.6 



tr. I 



^ 



2.1 

 16.5 

 72.0 



7.5 



V 



4.6 

 60.0 

 31.0 



.7 



I 

 I 



1.5 

 72.3 

 23.8 



2.1 



Y 



sand, which has settled in the eddy in the lee of the larger 

 drift. *) The sand in the lee drift, as it may be called, is 

 found to be a little finer than the dune sand proper. Its 

 grains have been lifted a little higher, and that is the 

 reason why they have been carried a little farther. But 

 the difference is very slight and consists merely in a 



"■) See Die Denudation in dcr Wiiste etc., .Johames Walthor, p. 172, fi"-. 80. 



