518 



THE WONDERS OF GEOLOGY. Lect. V. 



which are spread the inferior oolite strata, full of charac- 

 teristic fossils ; and above are beds of laminated calcareous 

 stone, locally termed the Collyweston slates, from being 

 quarried in that neighbourhood. These deposits, therefore, 

 occupy the same geological position as the Stonesfield slate 

 of Oxfordshire and of the Cotteswold hills, and contain 

 similar marine shells. The upper series consists of marly 

 limestone and shale, with concretionary sands ; the fossils 

 are shells of the genera Nerincea, Lucina, Modiola, &c. 

 with numerous fragments of the leaves of ferns (especially 

 of Pecopteris polypodioides), and of cycadeous plants. 

 These beds are regarded by Captain Ibbetson and Mr. 

 Morris, as the equivalents of the carbonaceous shales of 

 Scarborough and Gristhorp bay ; in fact, as the seaward 

 extension of those fluvio-marine strata; those of Stones- 

 field appear to have been synchronous, but deposited 

 farther from land, in the depths of the oolitic ocean. 



23. Carboniferous Oolite of Brora. — Carboniferous 

 fluvio-marine deposits of a similar character, and of the 

 same age as those above described, occur in the north of 

 Scotland.* At Brora, on the south-east coast of Suther- 

 landshire, intercalated between oolitic calcareous strata 

 and Lias shale, there is a series of deposits, consisting of 

 layers of coal interstratified with sandstones and shales, 

 containing remains of terrestrial plants, and a few fresh- 

 water shells and cyprides. And in the neighbourhood of 

 Elgin, and on the north-east coast of the Tsle of Skye, shales 

 and sandstones, with impressions and remains of similar 

 plants, are met with, superimposed on the Lias.f 



The calcareous strata of Brora contain numerous fossils 



* Fcr a general view of the geological phenomena of Scotland, I 

 would strongly recommend the reader to obtain the charming and 

 instructive little volume by Mr. James N icol, Curator of the Geological 

 Society of London, entitled, A Guide to the Geology of Scotland, 1S41. 



t Sir R. Murchison, in Geol. Trans, vol. ii. p. 293. 



