2G JUIUFTIXG SAND. 



Tlioug'li it is not supposed that all duue sand is as uni- 

 form in composition as are the specimens described here, 

 it seems probable that the wind forms drifts mainly of 

 grains which measure from one half to one eight of a milli- 

 meter in diameter. How promptly it selects just these 

 sizes for drift-building, may be seen in the composition of 

 some specimens of sand collected from widely distant 

 places, where it has just begun to work on materials of 

 quite diversified composition (Tab. XY). In the following 

 table one sample (no. 59) was collected in Kansas in a 

 bottle placed about a foot above the ground in a drifting 

 cultivated field, where the soil held gravel as well as clay; 

 one (no. 60) was taken from the surface of a snow-drift in 

 Maryland, where the deposit had blown from an exposure 

 of Potomac sand of somewhat heterogenous composition; 

 one (no. 61) is from a gutter in the city of Baltimore 

 and was sifted out by the wind from the dust on a paved 

 street; one (no. 62) is from the beach at St. Augustine in 

 Florida where such sand is reported to be tossed about 

 by the sporting wind with pai'ticular ease, owing to the 

 fact that the water has already affected a most favorable 

 sorting; and one (no. 63) was collected in a small recept- 

 acle placed on a drifting railroad bed in the western part 

 of Illinois. The chief ingredient in these sands is alike in 

 all and is of the same grade as that found in dune sand. 



