SUMMARY. 225 



defined near its upper limit by most characteristic red quartz shales, 

 which forms the base of the richly fossiliferous lower silurians. 

 Structurally, this system is very much more fully developed than the 

 succeeding silurians, being in most sections more than double the 

 thickness of the latter. But the lower limit of the haimantas is 

 obscure ; an almost perfect lithological passage may be traced from 

 the crystallines (vaikritas) into this system, both in the western'and 

 easternmost sections described. 



One of the most characteristic amongst the various horizons in 

 this system is a great thickness of a coarse conglomerate or boulder- 

 bed, which in some sections alternates with slaty beds, but is never 

 entirely absent. This, in conjunction with the ripple-marking which 

 may be seen on nearly all the slaty beds of the haimantas, indicates 

 clearly that we must suppose the ancient coast-limits of haimanta 

 age to have been in close proximity. The apparent overlap of hai- 

 mantas on gneiss (Niti area) is easily explained, if we suppose this 

 system to have been developed in this region as a littoral formation. 

 It is extremely probable that one of the earliest Himalayan disturb- 

 ances occurred immediately before haimanta times. 



Lithological resemblance, not less than structural features, point to 

 the probability that a part at least of the slate series of the Lower 

 Himalayas are equivalents of the haimanta system of the Central 

 Himalayas. I believe even that some of the older rocks, which 

 immediately underlie the Vindhian group, may yet be found to belong 

 to the same age. It would thus follow that the haimanta seas had ex- 

 tended not only over the greater part of the present Himalayan area, 

 but perhaps also as far south as Central India. If so, the line of the 

 Central Himalayas was probably marked out as a chain of ele- 

 vations, from the waste of which the boulders and pebbles of the 

 haimanta conglomerate and of the Simla rocks were derived. 

 The latter supposition is also advanced by the authors of the 

 " Manual." 1 



1 Page 679. 



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