60 J. G. WALLER ON SAND. 



denudation and destruction to which it has been subjected. Belong- 

 ing, geologically speaking, to this series are two layers entitled 

 <( the Upper and Lower Greensand," separated from each other 

 by the Gault Clay. The Upper Greensand is best known to us 

 by the limestone, called familiarly clunch, firestone, hearthstone, 

 used extensively in the Middle Ages as a building stone, the Palace 

 and Abbey of Westminster having been mainly constructed of it 

 from the quarries of Merstham, though passing under the general 

 term of " Ryegate Stone." It was also used for effigies, and for 

 indoor purposes ; kept free from damp, it was durable, and pre- 

 served a sharp edge in its working. Dissolving the lime from it, 

 the deposit shows us nearly half to be finely comminuted quartz, 

 some few particles of flint equally fine, and a large quantity of 

 silicified casts of many species of foraminifera, and particularly of 

 one very minute in size, which I assume to belong to the Globio- 

 gerinas. Other forms I am not acquainted with, look like portions 

 of very minute encrinites, but I must profess my ignorance ; and 

 as the subject has been worked out by Ehrenberg, I suppose it is 

 well understood. I may remark, however, that these silicifications 

 have in composition a remarkable resemblance to that of chalk flint, 

 which would rather support the view of Mr. Hawkins Johnson, 

 that the latter was of organic origin. As a factor of the sand of 

 our coasts, this deposit could play but a small part, and may there- 

 fore be dismissed for the consideration of the lower bed. 



This bed is known as the " Shanklin " Sand, from its being so 

 well represented in that locality, and has at its base a well-known 

 building stone called " Kentish Rag." Taking some seams of 

 sand found with it for examination, I find one-half to be composed 

 of quartz, the other of dark opaque grains, which I cannot identify. 

 I have examined also other specimens from different beds, but the 

 result is the same. 



I will now, in conclusion, take a retrospective glance at the facts 

 presented before you. The one great fact is the predominance of 

 quartz. It is only in the two lower beds, " the Green Sand," that 

 this material is not in excess of every other, and even in them it 

 constitutes one-half, and in neither case does the chalk flint appear 

 but in very small quantities. That it should be almost absent 

 in the gravel composed of flint shingle, and from sand veins 

 found in the very midst of its rolled pebbles, is very surprising. The 

 quartz sand, of the gravel, has larger grains by three or fourdiame- 



