1858.] MUECHISON SAKDSTOj!fES OF ELGrllST. 419 



December 15, 1858. 



The Eev. J. H. Austen, Ensbiuy, Dorset, The Re7. Alexander 

 Maclennan, M.A., Eectory, Newington Butts, Surrey, John Sharp, 

 Esq., of the Inner Temple, Barrister-at-Law, Tunbridge Wells, 

 Henry Christy, Esq., Victoria Street, Westminster, and Joseph 

 Paull, Esq., Moor-master, Aldstone, Cumberland, were elected 

 Fellows. 



The following communications were read :— 



1. On the Sandstones of Moeayshtre (Elgin, Sfc.) containing Rep- 

 tilian Remains ; and on their JRelations to the Old Red Sandstone 

 of that Country. 



By Sir Rodeeick I. Muechison, G.C.St.S., E.R.S., Y.P.G.S., &c. 



Introduction. — In the preceding memoir the whole succession of 

 the inferior crystalline and stratified rocks having been indicated, the 

 triple arrangement of the Old Red Sandstone in an ascending order 

 was shown to consist of a lower red sandstone and conglomerate, of 

 a central deposit — the grey Caithness Flags, and of certain overlying 

 sandstones, occasionally red, but of prevailing yellowish colour. 



In this manner the whole of the Old Red series (or the equivalent 

 of the Devonian rocks of other countries) is exhibited in the Orkney 

 Islands, Caithness, and Easter Ross. 



The lower division of the series in those tracts has not (see above, 

 p. 400) afforded any of those fossils (the Pterygotus, Cephalaspis, 

 Pteraspis, or Parka decipiens) which characterize the lowest Old Red 

 of Forfarshire, Perthshire, Shropshire, and Herefordshire : the middle 

 division (or Caithness Flags) is abundantly characterized by ichthyo- 

 lites and the small crustacean Estheria : the third, as known to the 

 north of the Moray Firth, has afforded, as yet, certain terrestrial 

 plants only, which, approaching to the Carboniferous types, are forms 

 hitherto unknown in any true Carboniferous deposit. 



In following this natural physical group westwards along the 

 north coast from Caithness into Sutherland, or northwards from the 

 Orkneys into the Shetland Isles, its bituminous flagstone or central 

 portion is seen to thin out. Such is also particularly the case in the 

 southern extension of the group ; which we proceed to consider. 



Thus, after passing along the east coast of Sutherland, where the 

 lower member only is visible, it is already important to remark, in 

 reference to what is afterwards to be noticed on the south side of 

 the Moray Firth, that at Dornoch, where the stone is quarried on 

 the sea-shore, it is of a decided yellow colour ; whilst there, and 

 also near Tain, such yellow sandstones, which are largely used for 

 building-purposes, graduate downwards into and are fairly interlaced 

 with the Old Red Sandstone*. 



* The detailed relations of the Red and Yellow Sandstone in the environs of 

 Dornoch and Skibo Castle are much obscured by accumulations of gravel, forming 

 remarkable ridges Uke the " asar " of Sweden. 



