274 PROCEEDIN^GS OF THE GEOLOGICAL SOCIETY. [Feb. 7, 



At Invernettie, near Peterhead (see Quart. Journ. Geol. Soc. vol. 

 xiv. p. 518, 1858), the base of the section shows fine stratified clay 

 and sand free from stones, above which there is a thick mass of 

 rough pebbly clay like that of Caithness, containing well-scratched 

 boulders of granite, sandstone, &c., with some broken sea-shells, 

 which also show traces of glacial scratching. Here, then, we have 

 a mass of unstratified drift closely resembling that of Caithness, 

 and from its position above the fine laminated clay apparently later 

 than at least a part of the glacial-marine beds. 



But the glacial deposits at King-Edward, in Aberdeenshire, throw 

 still more light upon the relations of the Caithness beds. Some 

 sections recently laid open there have enabled me to understand 

 their arrangement far better than formerly. At this locality there 

 are deep masses of unstratified pebbly mud of a dark-gTcy colour, 

 very hard and firm, containing stones (some of which are ice-worn 

 and striated) and fragments of shells, which are likewise occasionally 

 scratched. It is, in short, so like the Caithness Drift in every re- 

 spect — in colour, texture, and organic contents — that I can perceive 

 no difference between them. It has been called " the Boulder-day''^ 

 by Mr. Eobert Chambers, who visited the locality in 1855 *. Besides 

 this coarse stony mud there are some beds of fine stratified sand, 

 which often contain remains of shells in considerable abundance, 

 most of them broken, but many of them entire. The bivalves 

 always occur in detached pieces and want the epidermis, as if they 

 had been washed about by water. This, I believe, is the bed that 

 yielded Hugh Miller's specimens, and from which I have obtained 

 most of the species enumerated from King-Edward in my paper on 

 the last geological changes in Scotland. But there is another bed 

 of fine dark-grey silt, free from stones, containing Arctic shells en- 

 tire, and apparently in situ, with the epidermis on. The Tellina 

 calcaria occurs here of large size, with both valves connected by the 

 ligament and shut, also Leda, Natica, and others ; they are very 

 sparingly dispersed in the silt, which contains streaks of black car- 

 bonaceous matter, proceeding probably from the decay of seaweed. 

 It also contains Foraminifera. This bed of silt I noticed in 1857 ; 



Eig. 6. — Section at King-Edward, Aberdeenshire. 



1. Valley-gravel. 



2. Pebbly clay. 



3. Fine sand with shells. 



4. Fine silt with shells in situ. 



5. Rock. 



* See ' Proceedings of Royal Society of Edinburgh,' Dec. 17, 1865. 



