100 



broken off iu just the condition to be dissolved. On the granite hills they 

 would find masses of debris along the roads and watercourses which looked 

 like ground rice ; this was the quartz which had been left by the rain after 

 the mica and felspar had been washed out. There occurred to him a 

 notable instance of sand which was not quartz, and that was the sand from 

 the River Parrot, of which what were called Bath bricks were made. This 

 sand contained a great deal of matter of very much the same character as 

 flint, to which the peculiar sharpness and cutting property of the material 

 was due ; it was not exactly flint ; probably it was chert. 



The President said Mr. Waller had referred to the use made by small 

 animals of the grains of quartz ; he should like to ask if it was found that 

 the arenaceous Foraminifera selected quartz in the same way ? 



Mr. E. T. Newton said they were much indebted to Mr. Waller for bring- 

 ing this subject forward. There were one or two things in connection with 

 it w T hich he thought were not sufficiently noticed in books, Many people 

 were not aware that flint was so soluble as it was. Quartz was very much 

 harder and more durable, so that under the action of water and weather the 

 flint disappeared but the quartz did not, and so, as the quartz was likely 

 to stay and the flint to dissolve away, in course of time only the quartz was 

 left. It should be remembered too, that in earlier times England was not 

 a separate island ; the North Sea was at that time probably an estuary ; 

 and the climate being glacial, vast quantities of debris were doubtless 

 brought down and deposited. As to the small creatures mentioned as 

 having their cases composed only of quartz grains, of course that would 

 necessarily follow from the fact of their not being able to get anything 

 else. 



Mr. Michael said it struck him in the first place that the extreme ease 

 with which flint could be broken up might have something to do with the 

 matter. Some years ago when silica was wanted for glazing china, it was 

 obtained by heating flint and dropping it into water ; it could be then 

 pounded up quite easily, and formed a colloid with water. Another point 

 was, if the sand beaches were to be attributed to the attrition of the 

 granite, it was a singular fact that sand was so deficient in granite districts. 

 Such was the case, the beach on the granite coasts consisting almost 

 entirely of fine powdered shells, the deposit being in some parts 30ft. 

 deep. It was so in Cornwall, and he believed it w 7 as so too in the granite 

 districts of the Highlands and the Isle of Arran, where, though the 

 powdered granite was used for road making, there was very little sand. 



Mr. M. Hawkins Johnson said that though not exactly apropos of the 

 paper, he might mention that the probability was that where the action of 

 the sea was sufficiently violent to produce granite cliffs it would no doubt 

 be sufficiently so to wash away the detritus. An instance occurred to him 

 in the case of two rivers in the north of Scotland, the Spey and the Find- 

 horn ; both of these brought down granite detritus, and there was in that 

 district an immense quantity of sand ; but the sea there was not encroach- 

 ing as in some other portions of the coast. Mr. Johnson then showed by 

 means of a diagram drawn upon the board that the original construction of 



