GENERAL CONSIDERATIONS. 113 



the higher Himalaya as their ultimate source. In rocks of the 

 Sirmur series and the Siwalik series he has found schorl, garnet, 

 triclinic felspar and microcline, besides quartz shewing polysynthetic 

 structure and containing liquid cavities and microliths. He writes, 

 "All the above are eminently characteristic of granitic rocks and 

 could be matched over and over again in the granites and gneissose 

 granites of the Himalayas." At the very outset then we are re- 

 minded of the high probability that a barrier of crystalline rocks 

 existed in Tertiary times between the Sub-Himalayan deposits of 

 this side and those in the Hundes. 



The structure and fossil contents of the beds indicate the geogra- 

 phical conditions which prevailed during the 



Conditions under , . . . . 



which they were depo- deposition of the Tertiaries, as plainly as their 

 mineralogical composition indicates the nature of 

 the rocks forming the land from which they w r ere derived. The marine 

 origin of the Sabathu beds, and the fresh-water origin of the upper 

 Tertiaries, have long been recognised as facts. Moreover, the gradual 

 passage of the Sabathu clays into the sandstones of the Dagshai and 

 Kasauli stages has also been accepted as proving a gradual change 

 from marine conditions to those of fresh-water. Elevation was 

 clearly going on in the localities where these rock were laid down, 

 so that seas became estuaries, and estuaries dry land, and finally the 

 younger Tertiaries, namely, the Nahans and M. and U. Siwaliks 

 were deposited under conditions much like those under which the 

 present deposits at the foot of the hills are being accumulated. I 

 need not, therefore, make any further remarks upon this head, seeing 

 that the rocks of this epoch, in the district I am describing, agree in 

 all their facies with those as described by Mr. Medlicott. It is only 

 when the Himalayan area is left, and we pass on to the Salt Range, 

 the Suleman Range and the hills of Sind, that we find marine strata 

 of greater thickness, and encroaching somewhat higher into the 

 Tertiary series — a fact which indicates that the wave of elevation 

 took place from the east to the west, whereby the sea was driven in 

 that direction, and estuarine and fluviatile conditions supervened. 

 H ( I 7 I ) 



