140 PROCEEDINGS OF THE GEOXOGICAL SOCIETY. [Jan. 8, 



duced point, is that in the Elgin district the formation, which is 

 made up of the two well-marked members the Cherty Rock of 

 Stotfield and the Reptiliferous Sandstone, is altogether isolated, and 

 its stratigraphical relations therefore undeterminable. I believe 

 that I am supported in this conclusion by tbose who have made this 

 district the subject of their most constant and careful study. 



Under these circumstances a question of great importance arises — 

 namely, whether this remarkable formation exists in any other 

 district, where its relations may be the subject of more successful 

 investigation by the geologist. 



The beautiful Ross-shire section of the Old Red Sandstone, which 

 exhibits in a series of cliff-exposures a conformable succession of 

 beds, from the lower conglomerates of the Northern Sutor of Cromarty 

 to the light-coloured sandstone of Tarbet Ness, has been described 

 by Professor Sedgwick and Sir R. I. Murchison *, the Rev. J. M. 

 Joassf , and Professor Harkness J. The supposition originally put 

 forward by Sir R. I. Murchison, that the highest beds of this section 

 represent the Reptiliferous Sandstone of Elgin, appeared to derive 

 great support from the interesting discovery of footprints in these 

 strata at Portmahomack and Cambus Shandwick, which discovery was 

 made in 1863 by the Rev. J. M. Joass and the Rev. George 

 Campbell §. 



But, in spite of this most valuable discovery, I cannot but regard 

 this identification of the strata of Tarbet Ness with the Reptiliferous 

 Sandstone as a very doubtful one. In mineral character the former 

 much more closely resemble the light-coloured sandstones of Upper- 

 Old-Red age both in Elginshire and Sutherland. Too much weight 

 must not be attached to the presence of footprints, which might, 

 indeed, have been occasioned by Amphibians such as we now know 

 to have existed at as remote a period as that of the Lower Carboni- 

 ferous. Professor Elliot some years ago discovered what were sup- 

 posed to be footprints in the undoubted Upper Old Red Sandstone 

 beds of Nairnshire. This circumstance was brought under my 

 notice by Dr. Gordon, to whom I am indebted for so much assist- 

 ance in the study of this question. The slab on which these mark- 

 ings are seen was presented by Mr. Stables, of Cawdor, to the Elgin 

 Museum ; but, from examination of a cast of them, both Professor 

 Huxley and Professor Rupert Jones pronounce these markings to be 

 of exceedingly doubtful origin. 



The strongest circumstance, however, against the identification of 

 the Tarbet-Ness sandstones with those of Elgin is the absence 

 at the former place of that most remarkable, indestructible, and 

 easily recognizable stratum, the Cherty Rock of Stotfield. "When 

 we consider the manner in which the two members of the for- 

 mation are always associated in Elginshire, and the fact that the 

 preservation of the sandstones from denudation appears to be in 



* Trans. Geol. Soc. 2nd Ser. vol. iii. part i. 



f Quart. Journ. Geol. Soc. vol. xix. (1S63) p. 506. 



\ Ibid. vol. xx. (1864) p. 437. 



§ Ibid. vol. xix. (1863) p. 506. 



