Oil the Old Red of Scotland, 221 



Hall." ' It is interesting to note that " a large lamellibranch, closely 

 resembling the Irish Anodonta," 2 is met with in the Devonian of 

 New York. 



Concl 



usion. 



We freely admit that the geological opinion of the present clay 

 is largely in favour of the fresh- water origin of the Old Red 

 Sandstone. The unique character of the strata, the presence of well- 

 defined lake boundaries, and the absence of marine fossil remains 

 have been freely assumed, whilst supporting evidence is conspicuous 

 by its absence. In the Cambrian formation of Wales we find large 

 zones of red sandstones and conglomerates, rivalling, if not exceeding, 

 in extent similar deposits which characterize the Old Red Sandstone 

 of Scotland. The so-called boundaries of lake basins of the Old Red 

 Sandstone would be somewhat difficult to find, for (if we may use 

 the term) they appear to be " of a one-sided order." In the Welsh 

 area, the South of Ireland, and the North of Scotland, the Old Red 

 Sandstone runs out to sea ; while in Midland Scotland, if the Old 

 Red Sandstone thrown down by the great fault which stretches 

 across the country from Ayrshire to Midlothian were raised to its 

 original position it would show a south-eastward trend, towering 

 some 12,000 feet over the highest peak of the Southern Uplands. 



The marine denudation of the Silurian rocks of the Highlands 

 of Scotland is not in dispute, but Ramsay and Geikie have assumed 

 a subsequent lake or fresh- water denudation. The conformable 

 deposition, however, of the Old Red Sandstone upon the preceding 

 Upper Silurian deposits in the counties of Edinburgh and Lanark, 

 the Welsh area, and in the St. Lawrence basin, precludes any such 

 idea; for from the base of the Upper Silurian to the top of the 

 Lower Old Red Sandstone the sequence of these deposits is unbroken. 

 It therefore follows that the denudation of the rocks of the Highland 

 area being marine, the equivalent deposits occurring in the Upper 

 Silurian and Lower Old Red Sandstone are equally marine. We 

 find in the Moray Firth area a large stratum of yellow saliferous 

 sandstone, interbedded with shales containing remains of Old 

 Red Sandstone fishes. 3 This stratum of saliferous sandstone 

 is well exposed in the precipice of the Burn of Eathie, near 

 Cromarty, and we think but one conclusion alone can be drawn 

 therefrom — that the formation and its contained fish-remains were 

 marine. The widespread occurrence of so-called fresh-water 

 fishes in the Devonian of Russia, Central Europe, Britain, and 

 North America, renders the " Lake theory " view of the fresh-water 

 origin of these fishes utterly untenable. Finally, we feel justified 

 upon both physical and palaeontological grounds in concluding that 

 the Old Red Sandstone and Devonian, in their respective littoral, 

 shallow-water, and deep-sea deposits, represent the one Devonian 

 system, ichich is marine. 



1 Report Geol. Surv. Canada, 1871, p. 4. 



2 " Textbook of Geology," A. Geikie, 1882, p. 706. 



3 "The Old Red Sandstone," 4tk ed., 1850, p. 285. 



