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



taken into account. If, moreover, we take, with Prof. Ball,' " a 

 glimpse through the corridors of time," and are convinced even 

 a little by his arguments, we must make some allowance for the 

 disparity between the work of the tidal wave now and in the remote 

 past, even within the limits of the geological record, and therefore 

 be cautious in drawing inferences as to duration of time in a great 

 series made up largely of shore-, bay-, and lagoon-formations. It 

 is in their fauna and flora, and the enormous conti'ast which they 

 present at the close of the Carboniferous to what is found at the 

 close of the Triassic age, that we get something like trustworthy 

 data from which to reason. But neither on pal^ontological nor on 

 stratigraphical grounds can we take the fragmentary and fringing 

 strata of the series as they occur in Britain for the basis of such 

 a calculation. In the words of Prof. Credner, of Leipzig : ^ " Since 

 the more complete investigation of the Alpine Trias, we have learnt 

 to recognize formations of a remarkably similar facies (partly with 

 identical species) in Sierra Nevada (California), in Spitzbergen, in 

 N. Siberia, in New Zealand, and in the Himalaya. It appears 

 therefore that the Alpine facies of the Trias is not, as was supposed, 

 a special and local production, but rather the essential, peculiar, and 

 normal representative of the Triassic marine deposits. The German 

 Trias, on the other hand, is not the typical and truly proportionate 

 facies, but is merely local, consisting of shore-, bay-, and lagoon- 

 structures. Tlie Alpine Trias and the German or English Trias are 

 related therefore much the same as the Carboniferous Limestone to 

 the Culm, or the Devonian proper to the Old Bed Sandstone." In 

 the Alps the Permian strata are scarcely, if at all, represented ; it is 

 in the middle of Germany, in Thiiringia, in Saxony, and in the 

 country which lies to the south of the Harz Mountains, that we 

 must look for their typical development. 



The real question at present under discussion among English 

 geologists is : What shall be done with the Permian series ? 

 There seem to be insuperable objections to classing them with the 

 Trias, in spite of some lithological relation subsisting between the 

 two series, and of the fact that they are in places stratigraphically 

 conformable to one another. In Germany, where the palseonto- 

 logical distinction is the most pronounced, the graduation from the 

 Dyas upwards into the Ti'ias is most complete ; a fact which Mur- 

 chison fully recognized years ago.^ The following is Credner's 

 classification of the whole series : — 



/ 3. Keuper : a formation of marls, sandstone, and gypsum, with land- 

 rp-py.Q, 1 plant remains. 



j 2. MuscHELKALK : a calcareous formation -with remains of marine fauna. 



\ 1. BuNTER Sandstein : a shore formation with land-plant remains. 



i2. Zechstein-group : a formation of limestone, dolomite, and gypsum, 

 with remains of marine fauna (" Kupferschiefn- " as a base). 

 1 . RoTHLiEGENDE : a formation of conglomerates, and sandstones, with 

 remains of a land-flora. 



1 Vide Nature, Nos. 630, 631. A lecture by Prof. Eobert S. Ball, LL.D., F.R.S. 



2 Elemente der Geologie, Leipzig, 1876 (p. 352). 



3 Vide Siliiria, also a paper by Murchison and Morris, Q. J. G. S., vol. xi. 



