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



upcoming, and in any kind of waterway, but mainly in open fissures, 

 by deposit form metalliferous veins," I consider that these words 

 should be supplemented by, " if they contain sufficient quantities 

 of ores in solution," as we possess very many alkaline and saline 

 springs and waters, which form no metalliferous veins and no 

 metallic deposits. 



Metalliferous deposits are in fact constituted of metallic particles, 

 extracted from rocks by mother liquors, either with or without the co- 

 operation of carbonic acid, and accumulated in fissures, cavities, or 

 depressions. 



Mineral springs found in many metalliferous regions evidence the 

 former activity of mother liquors. 



Space will not allow more detailed explanations of the points 

 touched upon here to be given ; these must be sought for in a work 

 which I hope shortly to put before the public. It is gratifying to 

 me to learn that Professor Le Conte, as a result of his very valuable 

 investigations in California, has arrived at nearly the same con- 

 clusion about metalliferous deposits, as I did some years ago. 



VI. — On the Classification of Sedimentary Strata.^ 

 By W. T. Blanford, F.R.S., Sec. Geol. Soc. 



THE true test of the classification adopted for European sedimen- 

 tary formations is to endeavour to apply it in distant parts of 

 the earth. It will then be seen whether the classification in question 

 is real, or whether it is founded on local and accidental peculiarities 

 of the rocks in a particular region. 



So far as the geology of India has been studied, it appears doubtful 

 whether the sedimentary formations of that country can be accu- 

 rately classified by means of the European subdivisions. The 

 difficulty, it is true, is partly due to the paucity of fossils in Indian 

 rocks, but partly also to the circumstance that the breaks in the 

 sequence do not correspond with those especially remarkable in 

 Europe. For instance, it has not been found easy to draw an exact 

 line of separation between the uppermost Palaeozoic and lowest 

 Mesozoic strata at one of the very few localities where both ai-e 

 marine and fossil iferous, the Salt Eange of the Punjab. There 

 is, so far as is known, no physical break, the two systems being 

 perfectly conformable to each other, and the change in the fauna is, 

 to say the least, more gradual than in Europe, several Triassic genera 

 being found in the Upper Carboniferous series. Again, throughout 

 Sind, Baluchistan and the Punjab on the western frontier of India, 

 the uppermost Mesozoic strata underlie the lowest Ccsnozoic with 

 perfect conformity, and in one stage an intermediate fauna is found 

 between Cretaceous and Eocene. 



It is unnecessary to point out that similar observations have been 

 made in other parts of the world, and it follows as a reasonable con- 



' This paper has been drawn up for the Committee of Nomenclature of the Inter- 

 national Geological Congress to be held at Berlin, in September. 



