BEACH SANDS 



331 



2, the surface of each one, througli abrasion, being reduced to 

 the condition of ground glass. Examination with a high power 

 brings out minute fractures and conchoidal chippings, at once 

 suggestive of the preliminary stages of manufacture of the 

 quartz spheres for which the Japanese are so noted. It is as 

 though each granule had been held m the hand of some pigmy 

 aboriginal, and its surface reduced by hammering with another 

 pebble, after the manner known among arehseologists as 

 * Specking/' 



The shape assumed by a rock or mineral fragment subjected 

 to wave action varies somewhat with the nature of the material, 

 schistose rocks and easily cleavable minerals naturally giving 

 rise to pebbles or granules of quite unequal dimensions in three 

 directions. The schist on the coast of Cape Elizabeth, Mame, 

 for instance, gives rise to 

 pebbles in the form of a 

 greatly flattened oval, 

 while the more homo- 

 geneous quartz, with 

 which it is associated, 

 yields nearly spherical 

 forms. But of whatever 

 character the material, 

 the normal shape of a 

 beach-formed boulder or 

 pebble is oval, and this 

 for the reason that the 

 wave action is a dragging 

 rather than a carrying 

 one ; the stone is not lifted 

 bodily and hurled toward 

 the shore to roll back with 



the receding wave, but is rather shoved and dragged along. 

 Gravity tends to hold the fragments in one position so that 

 the wear is greatest on the side which is down, and this in 

 itself would cause them to assume an oval or flattened form 

 even were they spherical and of homogeneous material at the 

 start. "^ 



(3) ^olian Deposits. — We will now consider those deposits 



^Merrill, Preliminary Handbook, Dept. of Geology, XJ. S. National Mu- 

 seum, 1889, p. 23. 



Pig. 36. — Quartz granules in sand from 

 beach, Santa Eosa Island. 



