274 Rev. A. Irving — On the Permian and Trias. 



In the "Warwickshire area the case seems to be more doubtful. 

 Here the strata called Permian are generally conformable to the Coal- 

 measures, and present great uniformity of character throughout. 

 Their resemblance to the sandstone and marl series which underlies 

 the Permian breccias of South Staffordshire is pointed out by Mr. 

 Howell (loc. supra cit.) as having been first observed by Sir Andrew 

 Eamsay, and as having led him to suggest the removal of them from 

 their previous classification with the Triassic strata, with which they 

 are unconformable. The palgeontological evidence which they aifor'd 

 is very meagre, and of itself scarcely sufiicient to justify their separa- 

 tion from the Carboniferous series. The included fragments of the 

 specimens of the conglomerates of the series which I have seen are 

 nearly all well-rounded water- worn pebbles, or broken pebbles, and 

 a very high per-centage of them, the great majority in fact, consist 

 of Carboniferous Limestone ; their formation must therefore have 

 taken place at some time subsequent to the induration and exposure 

 to degrading influences of the strata of that formation. The areas of 

 their deposition were evidently more exposed to the surf-action of a 

 tidal sea than were those in which the Permian breccias further to 

 the west were formed. On the assumption that the so-called War- 

 wickshire Permians are stained Upper Coal-measures, it remains yet, 

 I think, to be shown why they are so much more marly than the 

 strata of that formation, and why the change in the colour of the 

 soil and in the general character of the country should be so marked 

 as it is in passing from one set of strata to the other. The question 

 of " staining " by percolating waters is not so simple as it is thought, 

 by some writers who speak of "stained Carboniferous" strata. The 

 action of free atmospheric oxygen held in physical solution by rain- 

 water in converting lower oxides of iron into the red peroxide can 

 be understood readily ; but how water can carry down this insoluble 

 peroxide (as seems to be assumed in some quarters), so as to furnish 

 a red cementing material for strata below, is not so clearly made out. 

 We ought therefore to be cautious in accounting in this way for the 

 great difference observable in the prevailing colour of two contiguous 

 series of strata, when both have been exposed for an immense time 

 to the action of atmospheric oxygen. Of course the reducing action 

 of carbonaceous matter present in the one series may prevent the 

 extreme stage of oxidation which takes place in the other, in which 

 carbonaceous matter is wanting ; but to admit this would be to go 

 far to surrender the point at issue. The same may be said, if it be 

 urged that one series is more pervious to water than the other. On 

 chemical grounds, I am strongly inclined to believe that the colora- 

 tion of the two great Red Series was (for the most part) contempora- 

 neous loitJi their deposition, and furnishes strong evidence of the 

 "continental" conditions under which that took place. For these 

 reasons I think the case of the Warwickshire Permians still an open 

 question. 



On the Relation of the Bimter to the Keuper. 

 It is well worthy of note that, as the investigation of the Trias 

 of England proceeds, the break between the Bunter and the Keuper 



