W. T. Blanford — Classification of Sedimentary Strata. 319 



elusion that the European classification can only be applied to 

 sedimentary formations in India and other distant countries as an 

 artificial scale or measure of comparison, the divisions in which are 

 founded on local phenomena existing in certain parts of Europe, and 

 mostly of Western Europe. 



The first essential condition to be observed in order that such a 

 scale may be of universal application is that the principal divisions 

 should be as nearly as possible of equal value. This value cannot 

 be determined by the local development or thickness of each sub- 

 division, nor by the evidence of discontinuity or break, usually 

 represented by unconformity, between them. It is notorious that 

 a thick system in one country may be represented by beds a few 

 feet thick in another, and that unconformity may occur between two 

 local stages not recognizable as distinct elsewhere. The only valid 

 evidence is the distinctness of the marine fauna, considered as a 

 whole, in each division, and in order to judge of this fauna rightly, 

 a large number of the characteristic types belonging to different 

 subkingdoms and classes must be taken into consideration. The 

 value* of plants, aud of land and freshwater animals is doubtful; 

 i\xej must certainly be considered apart from the marine fauna. 



At the same time any great change in the scale usually adopted in 

 Europe would defeat the main object, that of having a standard 

 classification for reference.^ 



With these preliminary remarks we may pass to a very brief con- 

 sideration of the systems. It would, perhaps, be best to admit, as 

 once proposed by Eenevier, only two major Palfeozoic divisions — 

 (1) Cambro-Silurian, and (2) Devonian-Garboniferous-Permian. But 

 it may be questioned whether there is any chance of such a pro- 

 position being accepted. The union of Cambrian and Silurian, how- 

 ever, has been agreed to by the Committee of Nomenclature at Zurich, 

 and will in all probability be accepted generally on the Continent. 



The Devonian system must probably be left. Permian is almost 

 purely European, not having been clearly recognized in any other 

 country. The fauna is not sufficiently distinct from the Carboniferous 

 to justify the retention of the Permian as a separate system, and the 

 division would in all probability never have been raised to that rank 

 but for the practical importance of its beds, on account of their 

 immediately overlying the valuable Coal-measures. The evidence of 

 the Indian Salt Eange section, in which the upper series of the 

 Carboniferous or Productus Limestone system (Waagen, Pal. Ind. 

 ser. xiii.) contains more Triassic forms than the Magnesian Lime- 

 stone of Europe, is entirely opposed to the separation of a Paleeozoic 

 system above the Carboniferous. The general classification would 

 be in every way improved by the Permian being considered as 

 Upper Carboniferous. 



Amongst Mesozoic divisions the Ehaetic alone requires notice. The 



' It will be found tliat the views here expressed have much resemblance to those 

 of Professor Dana (Manual of Geology, 1863, p. 125) and of Professor Eenevier 

 (Bui. !Soc. Vaud. Sc. Nat. xiii. pp. 229, etc.) It should therefore be staled that 

 the paragraphs as they stand above had been written before either of the works 

 named were consulted. 



