74 



GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Thickness. 



Passage beds. 



enough traverses could be made in the various parts of the Cen- 

 tral Himalayas to show how very uniformly the sub-divisions are 

 developed. 



The total thickness of the rhaetic with what remains of the lias is 



about 2,000 to 2,500 feet, though it may exceed 

 that in the Spiti area. 

 Whilst the lowest members of trias in the Himalayas are widely 



divergent from anything seen in the Alps, it 

 Alpine equivalents. . . . 



seems as if the similarity between the tnassic 

 and rhaetic formations in the Central Himalayan and Alpine regions 

 increases as one ascends in the group, until the rhaetic formations 

 are reached, which apparently are almost identical with the Alpine 

 rhaetics, not only in their fossil contents but also in lithological 

 character. 



There is not a sharply defined line between the limestones which 



I consider rhaetic and the genuine lias beds ; 

 grey Crinoid limestones in irregular thin layers, 

 and yielding numerous small Bivalves occur in between massive de- 

 posits of the rhaetic Lithodendron limestone, and these Crinoid lime- 

 stones containing as they do Brachiopods of Upper Kossen facies 

 must be considered as passage beds into the true lias. 



The uppermost beds (16) of the series consist of dark earthy and 



bituminous limestones ; the fossil remains which 

 Lias. . ... 



I have found in them are much too indistinct to 



allow close comparisons, but Stoliczka was fortunate enough to find 

 several good Alpine lias forms in this horizon, which is widely dis- 

 tributed over the Central Himalayas. By itself, however, the thick- 

 ness of this liassic horizon is inconsiderable and probably does not 

 exceed a hundred feet in any of the sections. 



Stoliczka included all the massive limestones of the upper rhaetic 

 above the beds with Megalodon with the lias (Tugling), but this I am 

 decidedly not inclined to follow. The Lithodendron limestone is inti- 

 mately connected with the underlying Megalodon beds and undoubt- 

 edly belongs to that series of strata. 



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