J. G. WALLER ON SAND. 65 



To understand the above analysis it would be well to see what the result 

 is in modern accumulations. Generally, it will be found, that the larger 

 grains of rounded quartz are the products of the sea-shore. The smaller 

 ragged characters are not so easy to account for; they resemble what is 

 produced by crushing with a hammer. This is exactly how it appears in 

 the ° Pebble Bed," that hard closely compressed mass of shingle which lies 

 beneath the London Clay. It may be, however, that these deposits of 

 finer sand are a sifting of smaller particles by a gentler action of water, 

 which, leaving heavier parts behind, carries off the lighter. There are, 

 certainly here some interesting questions for the geologist to determine, 

 and I have left much to be studied in the question of " Sand." 



