Rev. A. Irving — Tlie Permian- Trias Question. 321 



classification of Lower Mesozoic rocks should be founded not on 

 the useless and untypical German sequence, with two subdivisions 

 not marine, but on the Alpine sections, where nearly all the beds are 

 marine, the Rhfetic being the upper member or series of the Triassic 

 system. By adding the Rhaetic to the Trias the latter becomes more 

 nearly equal in importance to Jurassic and Cretaceous than it would 

 otherwise be. 



Of the Tertiary systems hitherto proposed, none except the Eocene 

 can be considered as of equal rank with the main PalEsozoic and 

 Mesozoic divisions. The method recommended by several German 

 and Swiss geologists of dividing the whole of the Tertiary strata into 

 two systems. Eocene, including Oligocene, and Neogene or Mollas- 

 ique, comprising Miocene and Pliocene, would be a great improve- 

 ment. But there appears so little probability of this classification 

 being adopted, that the only practicable suggestion appears to be to 

 unite the Oligocene with the Miocene, and to include the Pleistocene, 

 which has no claim to recognition as a separate system, in the Pliocene. 



These propositions lead to precisely the same conclusions as those 

 of the Swiss Committee of 1881 (Arch. Sc. Phys. Nat. 1881, p. 510 ; 

 and 1882, p. 53G), and to the subdivision of each of the major 

 categories ^ Paleeozoic, Mesozoic and Coenozoic into three systems. 

 Ail the terms of inferior rank to systems are even more local, and it 

 would greatly conduce to simplicity if a tripartite division of systenis 

 into series were adopted. If it be objected that such a subdivision 

 is artificial, the reply must be that, beyond the limits of Europe, only 

 an artificial scale is practicable. The accompanying is an attempt 

 at such a scale. It will be at once recognized that Jurassic, Triassic, 

 and Cambro-Silurian are easily divisible into three, whilst most of 

 the other systems present no difficulty. The most doubtful series 

 are Lower Pliocene and Middle Miocene. The names in italics are 

 merely suggestions, and are in no case new. 



It is possible that some of the subdivisions proposed may be 

 improved. For instance, it is a question whether the Upper Green- 

 sand or Cenomanian should be classed as Middle or Upper Cretaceous, 

 and there is much doubt as to the best division between Upper and 

 Middle Jurassic. The important principle is that all subdivisions 

 should be as nearly as possible of equal value, not locally but 

 throughout the world. 



VIT. — The Permian-Trias Question. 

 By the Eev. A. Irving, B.A., B.Sc, F.G.S. ; 

 of Wellington College. 

 T the present stage of the controversy, it may seem, to those 

 who have read carefully the paper of M. Marcou in the March 

 Number of this Magazine, that very little remains to be said. Yet, 

 however much it is to be regretted, it must be feared that insular 

 prejudice still finds place with English geologists, and prevents 



1 The use of the -word groups for these major divisions of sedimentary strata does 

 not appear acceptable to English geologists. 



DECADE HI. — VOL. I. — NO. VII. 21 



