138 SCIENCE PROGRESS. 



fossils occur ; and this passes up with perfect conformity 

 into the sandstones and clays of the upper part of the 

 Sirmur series. The average coarseness of the deposit 

 gradually increases in the upper beds ; and this gradual in- 

 crease of coarseness is maintained throughout the Upper 

 Tertiary or Siwalik group until we reach the very coarse 

 conglomerates of the Upper Siwalik. 



West of the Jehlam the whole series is said to form a 

 perfectly conformable sequence ; and many of the sections 

 in Kumaun and Gahrwal show a similar conformable 

 passage from the Lower Tertiary to the Middle Siwaliks 

 and from the Middle to the Upper Siwaliks. But this is 

 not invariably the case ; and in many places, especially 

 towards the interior of the chain, the Upper Siwaliks rest 

 upon the upturned and eroded edges of the Lower Siwaliks. 

 Only one explanation is possible, namely, that the series of 

 rocks was deposited during a period of disturbance, and that 

 while continuous deposition went on in one area, in another 

 the beds were raised and denuded and buried again. 



Along the whole length of the Himalayan chain, 

 wherever the Siwaliks are in contact with the pre-Tertiary 

 rocks, the line of junction is a great reversed fault. In 

 places this fault lies between the Lower Tertiaries and 

 the older rocks ; and in one area it lies between the Lower 

 and Upper Tertiaries. Similar great boundary faults are 

 not uncommon — indeed they are probably almost universal 

 along the margins of great mountain chains ; — but the 

 peculiarity 1 of the Himalayan fault is that it is also a 

 boundary of deposition. The Tertiary series never extended 

 much to the north of the fault ; for it is impossible to believe 

 that the whole enormous thickness of these beds could have 

 been removed so regularly and so completely as to leave no 

 outliers. 



Hence the conclusion is irresistible that during the de- 

 position of the Sub- Himalayan Tertiaries the boundary of 

 the Himalayan Range coincided approximately with this 



1 1 am far from believing that this feature is really peculiar to the 

 Himalayan Range ; but it is more conspicuous and has been more clearly 

 proved there than perhaps in any other chain. 



