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



223 



sandstones, wtiicli in one place attain the tliicl^ness of 2000, and in 

 another the enormous thickness of 5000 feet (Harkness, loc. supra cit.). 

 Later and more detailed examination of this district by the officers 

 of H. M. Geological Survey has shown that the main masses of the 

 " Penrith Sandstone," whose great dimensions have just been men- 

 tioned, are upon the whole homotaxial with the principal brecciated 

 masses known as tlie " Brockram " ; so that the relation of these two 

 chief members of the series, as they pass horizontal!}'' into one 

 another, may be roughly represented by the following diagram, for 

 which I am indebted to the kindness and courtesy of J. H. Good- 

 child, Esq., of the Geological Survey : — 



Penrith. 



Appleby. 



Xirkby Stephen. 



Older Palaeozoic Eocks (highly inclined). 



These few facts presented by our north-western area must make us 

 hesitate before we pronounce the strata which occur there to be 

 " coloured Upper Coal-measures," or even " stained Carboniferous " ; 

 indeed, if any weight at all is to be allowed to a comparison of them 

 with the facts presented in the Rothliegende of Germany, we can 

 hardly do so, without classifying that great formation of the Conti- 

 nent also with the Carboniferous. Until we are prepared to do this, 

 we must, it seems to me, from the evidence before us, admit that 

 there is to be found in the Eden Valley and the adjoining country 

 a true equivalent of the lower Dyassic formation of the Continent. 

 These remarks apply of course only to the strata which have been 

 mentioned ; the tFpper Sandstone series known as the " St, Bee's 

 vSandstone " is excluded, for reasons already given. With this 

 limitation the Permians of the Carlisle Basin will bear comparison 

 upon the whole with the Rothliegende of Germany in several places, 

 and especially in those parts where it is not succeeded by the Zech- 

 stein formation. I go further, and make bold to say that they bear 

 comparison with the great Permian series of Russia (at least with 

 the lower portion of that series), where, in a completely undisturbed 

 area extending from Moscow to the Ural Mountains and north to the 

 shores of the Arctic Ocean, the interbedded calcareous and dolomitic 

 deposits, with their contained fossils, show what were the prevalent 

 marine conditions in an area free from the direct influence of dis- 

 turbing agencies, during a time when large portions of the German 

 and British areas were thrown into tumultuous confusion. 

 {To be concluded in our next Number.) 



