184 NEW YORK STATE MUSEUM 



Anotlior source of the variations in clay texture and a cause of 

 sandy partings lies in the fine sand and dust blown out over bodies 

 of water by the winds. Such subaqueous deposits it is believed 

 are more widespread than has generally been supposed. The 

 agency of the winds is readily recognized when the product trans- 

 ported is volcanic ash, but in the case of ordinary sands and rock 

 dust it is less easy to determine the wind-borne origin of the 

 material when laid down under water.^ 



The abundant evidence of the deflation of the sandy and grav- 

 elly' plains left bare by the retreat of the ice in the eastern United 

 States and the extent to which such sands are now being blown 

 away from one tract and accumulated on another makes it 

 highly probable that eolian deposits would be made in bodies of 

 water and particularly in this latitude in the warm months of 

 the year for during the winter snow^ and ice protect the sand from 

 wind action. These sands in New England usually blow during 

 the times of dry w^esterly winds, for the reason that easterly moist 

 winds by the films of hygroscopic water which they permit to 

 collect about the dust particles cause them to adhere and resist 

 the action of the wind. These alternations of moist and dry con- 

 ditions, of easterly and westerly winds, occur at the present time 

 with singularly frequency owing to the movements of cyclones 

 across the eastern United States. As noted by Clayton, rainy 

 days with easterly winds recur about once a week and so do the 

 following westerlies. Applying this possible cause of the inter- 

 lamination of fine sand3^ layers with the glacial clays as they 

 occur in the Upper Hudson valley, the clay layers would corres- 

 pond to times of wet conditions when discharge from the ice 

 would be most active; and the films of sand would correspond to 

 longer or shorter episodes of strong w^esterly winds according to 

 the thickness of the bands. In this view, the summer time of 

 mai'ked development of the interlamination should be distin- 

 guishable from the winter time of almost continuous clay deposi- 



*For instances of wind-borne dust and fine sand showered do-v^ii over 

 water bodies, see Verbeck, Chevalier. Krakatoa and the appended charts ; 

 Reclus, E. New Physical Geography, vol. 2, The Ocean. N. Y. 1886. 

 p.]98^200; Darwin, Charlos. Naturalist's Voyajxe Around the World. 

 N. Y. 1S87. p. 5; Marsh, (J. ]'. 'J'he Karlh as Modilied by Human Action. 

 N. Y. 1874. P.545-G08 ; Bather, F. A. Wind-worn Pebbles in the British 

 Islands. Geo!. Ass'n Proc. June, 1900. lG:39G-420, with bibliography; 

 Meunier, S. La g6ologio expcrimentale. Paris. 1899. eh. 0. p.208-lG. 



