226 



GR1ESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Palseozoiclgroup. 



Permian to lower lias. 



The palaeozoic group forms an uninterrupted sequence from the 



lowest haimantas to the upper carboniferous ; 

 and this sequence is the same, or nearly so, in 

 all the sections of the Central Himalayas. The first indications of a 

 disturbance are noticeable in the upper carboniferous. Certain beds 

 of the latter are wanting in some sections, and I found the next fol- 

 lowing system overlapping what I must look upon as an eroded 

 surface of upper carboniferous. 



Nearly everywhere I found the latter overlaid by a great sequence 



of beds, which represent permian, trias, rhaetic 

 and lias. This group of systems forms an un- 

 interrupted sequence, with conformable bedding throughout. The 

 base of the sequence is everywhere seen to be dark crumbling shales, 

 which contain a palaeozoic fauna, probably permian in character, 

 which gradually passes into lowest trias beds through dark limestones 

 and shales which has yielded a curious fauna, some of the species of 

 which have strong affinities with permian forms. On it rest lower 

 trias beds, followed by a continuous succession of strata, which reach 

 up into the lower lias. 



The same condition prevails in Spiti, where the lower lias is also 

 well represented. 



The lias limestones and shales are overlaid by Jurassic (Spiti) 

 Jurassic Spiti shales. beds > which have yielded a large number of 

 Cretaceous. fossils, but which have not yet been entirely 



examined. Most of them appear to belong to the upper jurassics 

 rather than middle or lower. Whether the latter is represented or 

 not, is not quite clear, but the bedding of the Spiti shales is isoclinal 

 with the lower lias, and if there is an unconformity between these 

 systems, it may only be conjectured from the sudden and entire 

 change in lithological character of the two formations, coupled with 

 the absence of lower Jurassic forms amongst the species found in the 

 Spiti shales. 



From this formation there is a gradual passage into the greenish 

 shales and sandstones of the cretaceous (with perhaps upper Jurassic), 

 ( 226 ) 



