TERTIARY SANDSTONES, CLAYS, &C. 67 



other erosive action upon the subjacent limestone rock, or some in- 

 stance of complete discordance of stratification, would be found. 



Conditions. — The great thickness of these tertiary sandstones, &c, 

 and their endless alternation of arenaceous and argillaceous strata 

 supposed to have been accumulated in shallow water, would point to a 

 gradual subsidence of the basin, or lake, or sea which received them in 

 order to allow of such a depth of beds being superimposed. A correspond- 

 ing elevation of the Himalayan rocks from the erosion of which they 

 were probably formed may have taken place during a period which 

 must have been protracted and longer still if the salt series and 

 nummulitic limestone are all included, involving some uncertainty as to 

 its early conditions when the waters, if not of the sea, must Kave aj} 

 least been salt. Fresh water deposition may have succeeded, but there 

 is nothing to define the exact place at which any change in this respect 

 occurred, for the mammalian and fresh water reptilian remains could 

 have been brought by rivers into the sea. And there is almost as little to 

 mark the close of the epoch or link its geological events with those of re- 

 cent geological time, the highest beds known having suffered denudation 

 to an undeterminable extent, so that it is impossible to say what was 

 the most recent conformable deposit of the period. 



The boulder beds of the upper part of the formation, or what 

 remain of them in this region, occupy situations which might favour the 

 idea suggested in Mr. Medlieott's Memoir (so often referred to), that 

 the boulders travelled through spaces approximately coinciding with 

 existing lines of drainage, if their identity could be absolutely established 

 with the rocks in the interior of this part of the Himalayan region. The 

 probability is strong that they were thence derived, and gathers still 

 further strength from the upper beds being apparently the source of the 

 Punjab stream gold, which is washed in a few localities in this region as 

 elsewhere.* 



* Sec Dr. Fleming's account in his Salt Range Reports. 



( 171 ) 



