Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/185

1873.] JUDD-THE SECONDARY ROCKS OF SCOTLAND. 141 every instance due to the indestructibility of the overlying cherty rock, the absence of this latter in Ross-shire becomes the more inexplicable. No importance can be attached to the fact which has been pointed out that fragments of the rock are found on the beach near Tarbet Ness, as, owing to their intense hardness, similar rolled fragments are common all round the shores of the Moray Firth.

Although we may reject the evidence of the footprints of Tarbet Ness as supporting the identification of the sandstones of that place with the reptiliferous beds of Elginshire, yet the great interest and importance of the discovery remains. Indeed that interest is greatly heightened if, by the separation of them from the Reptiliferous Sandstone of Elginshire, we are able to remove all reasons for doubting their Old-Red age; for we may, in that case, regard it as proved that beings higher in the animal series than fishes existed at as early a period as that of the Upper Old Red Sandstone.

The difficulties in which, as we have seen, the question of the relations of this remarkable formation is involved on the southern side of the Moray Firth disappear, I believe, when we examine it on the northern side of the same Firth. In the county of Sutherland, at a distance of 30 miles from Stotfield, both the members of the formation occur; and the sections, fortunately, are of such a clear character that, while on the one hand they satisfy the observer as to the identity of the rocks on the north with those on the south of the Firth, they, on the other hand, leave no room for doubt as to the true position of these rocks in the geological series.

I am indebted to the Rev. J. M. Joass for first calling my attention to some patches of a peculiar rock imperfectly exposed in the Burn of Golspie. Subsequent study of the district enabled me to trace this rock, partly by small exposures and partly by the exact records of the position of old lime-pits &c. in Farey's Report on the district (to which I have already alluded), through its outcrop of nearly two miles in length to the reefs on the shore between Golspie and Dunrobin, where its relation to the series of Secondary strata is perfectly evident. A careful examination and comparison of the rocks on both sides of the Moray Firth convinced me that this rock was no other than the Cherty Rock of Stotfield, and that it was underlain by a series of sandstones with similar characters to those of the reptiliferous beds of Elgin. My friend Dr. Gordon has since informed me that some years ago, on being shown the isolated patches of rock in the Golspie Burn (concerning the relations of which nothing was at that time known), he at once pronounced them to be identical in character with his "Cherty Rock of Stotfield."

I have already pointed out the highly distinctive characters of this remarkable rock, which characters are exhibited in the most striking manner by the Sutherland deposit. We have the same peculiar cream-coloured limestone, occasionally crystallized, with like irregular cherty nodules, the whole mingled with the same greenish argillaceous mineral. Indeed, when we compare a series of specimens obtained on the northern side of the Firth with one from the southern side, the rocks are found to be absolutely undistinguish-