150 KRAFFT: EXOTIC BLOCKS OF MALLA JOHAR. 



A careful examination convinced me that these were laid down 

 on the slopes of large reefs of dachsteinkalk, which they eventually 

 overlapped, owing to a rise in the coast line. This, in connection 

 with the occurrence of breccias, proves them to have been formed in 

 comparatively shallow water. 



We therefore come to the conclusion that the red Alpine limestones 

 are not deposits of a deep sea, but of comparatively shallow water in the 

 vicinity of grey limestone reefs, and we may conclude that the origin 

 of the red Tibetan limestones was a similar one. On the other hand 

 stress must be laid on the absence of sandy and shaly materials, which 

 clearly points to an open sea, and this is no doubt, as Mr. Griesbach 

 suggests, 1 owing to the Tibetan rocks having been deposited at a greater 

 distance from the old Indian continent, than the Himalayan series. 



From the above it appears improbable that red limestones should 

 be of wide and equal distribution within the Tibetan series. More likely 

 they represent local formations, while grey limestones form the predomi- 

 nant rock, and we may suppose that they pass into the latter in the 

 same way that the noric Hallstatt limestones pass into dachsteinkalk. 



This conclusion would be well in accordance with the observation, 

 that within the volcanics of Johar grey limestones, mainly in huge 

 masses, form the most prominent foreign element, whereas the red 

 blocks — at least as far as size is concerned— play a comparatively 

 unimportant r61e. 



If the above be correct, it would of course follow that the grey 

 do'.omitic limestones represent not only dachsteinkalk but have a 

 considerably wider range. The term " dachsteinkalk " applied to 

 them must accordingly be understood to be of a provisional character. 



In the foregoing remarks the exotic blocks, representing Spiti 

 shales, Gieumal sandstone and upper flysch were left out of con- 

 sideration. There is no reason why we should not assume them to 

 have come from the same regions as the limestone blocks and we may 

 conclude that the Jurassic and cretaceous divisions following above 

 the Tibetan series are of a character lithologically identical to those 

 seen along the Indo-Tibetan frontier. 



1 Loc. cit., p. 25. 

 ( 24 ) 



