156 Rev. A. Sedgwick and Mr. Murchison on Deposits contained heticeen 

 posed to be derived from OithoceratiteSj but which we cannot regard as 



organic. 



Before terminating this short description of the sandstone and conglomerate 

 of the north-west coast, it is necessary to notice a deposit which commences 

 a httle to the west of an ancient chapel on the south shore of Loch Groinard, 

 and extends, with some interruptions, nearly two miles towards the south-east. 

 Its lower portion is coniposed of beds of red conglomerate, of red and varie- 

 gated micaceous sandstone, of incoherent red sand, and of red and variegated 

 marls. In its upper portion are beds of micaceous slate-clay, and of marl, 

 red, green, and variegated ; and these alternate with irregular beds of grey, 

 greenish grey, and white siliceous sandstone. This upper series very nearly 

 resembles some beds which in the Isle of Skye and in Applecross underlie 

 the lias ; and the whole system (which is inclined at a small angle, and is 

 entirely unconformable to the prevailing red sandstone of this part of the 

 north-west coast) might represent the new red sandstone of England in its 

 most characteristic form. 



Conclusion. 



It only remains for us by way of conclusion, to compare the deposits de- 

 scribed in this paper with the corresponding formations of the English secon- 

 dary series. We see no reason for believing that the old conglomerates and 

 sandstones of Caithness and the Murray Firth, belong to an epoch anterior to 

 the old red sandstone of England ; and the same conclusion must, we think, 

 be applied to the red sandstone on the north-west coast of Scotland, between 

 Applecross and Cape Wrath. They must, therefore, be contemporaneous with 

 some of the English series between the old red sandstone and the lias. 



We have little hesitation in identifying them with the old red sandstone, for 

 the following reasons. 



1st. They are identical in structure with the older red conglomerates of 

 Cumberland and the Isle of Arran. 



2nd. They alternate with, and are inferior to, many beds resembling grau- 

 wacke, but not resembling any rock subordinate to the new red sandstone in 

 England. 



3rd. They contain many extensive, concretionary masses of limestone in no 

 respect differing from the cornstone of Herefordshire, which is subordinate to 

 the old red sandstone. 



4th. They are identical with the conglomerates on the south flank of the 

 Grampians, which appear to be older than the coal-measures of Scotland. 



5th. They are, in Easter Ross, associated with a deposit of sandstone, which 



