6o PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



than normal. I have long ago shown that this material was drifted 

 from the north-east, and was mainly derived from granitic rocks 

 probably lying in that direction, but now no longer visible. They 

 must, however, I think, have been at a considerable distance ; and 

 yet we see that the grains were very little, if at all, worn in being 

 drifted so far along the bottom, even if we altogether disregard 

 the effects of local agitation. 



Taking, then, all the above facts into consideration, it appears to 

 me sufficiently proved that a great amount of drifting and mecha- 

 nical action must be required to wear down angular fragments of 

 quartz into rounded grains j^-jj inch in diameter, which I have 

 taken as the standard for comparison. I now proceed to consider 

 what appears to me a good illustration of how this wearing-down 

 may be explained when it does occur. 



Gt^een Sand of the South of England. — I have examined specimens 

 taken in various places from Devonshire to Kent ; and the facts 

 seem as though they would be of much interest if confirmed by 

 more complete examination. In the Haldon-Hill district the 

 grains are mainly angular, only -^-^ being well worn. Passing to 

 the Isle of Wight this rate increases to -J- ; and in Sussex and Kent 

 it further increases to ^ and ^. I must say that I feel much 

 tempted to explain these facts by supposing that on the flanks of 

 Dartmoor we are near to the granitic rocks from which the sand 

 was derived, and that in being drifted from it further and further 

 eastward, the grains were more and more worn. This does, indeed, 

 seem so very probable, that perhaps we may provisionally adopt 

 some such explanation of the facts. 



Hastings Sand^ Sfc. — This conclusion is strengthened by the 

 character of the other sands of the S.E. of England. The Hastings 

 Sand at Hastings, and the Thanet Sand from Crossness are about 

 •i- worn, and that of the modern Thames, near Eichmond, about ^ 

 worn, which is in striking contrast with the perfect angularity of 

 the sand of the Tay, and clearly indicates the great antiquity of the 

 grains and the great distance to which, at one time or other, they 

 have been drifted from their original source in crystalline rocks. 



New Red Sandstone. — I have examined a number of specimens 

 from various places, extending from Scotland right dow^n to Devon- 

 shire ; and what struck me most was the comparatively uniform 

 extent of the w^earing. My estimates of the relative number of 

 well-worn grains varied from 4- to ^. The only important differ- 

 ence is in a specimen from Leamington, vrhich is so far corroded 

 that the angular grains appear more numerous. 



We can thus draw no very certain conclusion as to the source of 

 the material, unless indeed it be that we as it were cross the 

 line of drifting transversely in passing from north to south. The 

 modern sand of the dunes at Southport is no more worn than that 

 of the beach ; and both are very much like the New Eed Sandstone, 

 from which probably they have been mainly derived. 



Lower Neiu Bed, Sfc. — I have already referred to the extreme 

 angularity of the grains in the Lower Coal-measures of South 



