1854.] STRACHEY — PHYSICAL GEOLOGY OF THE HIMALAYA. 253 



logical period to the present time. In this was pointed out the 

 probable existence of land with mountains already of considerable 

 altitude, in the earliest ages ; and to the general elevation of these 

 older heights with the rest of the area, the position of the great line 

 of Himalayan peaks was attributed, rather than to any special energy 

 of upheaval along that particular line in any of the later changes. 

 Until the commencement of the Tertiary period we can say little of 

 the state of the area, but then the nummulitic sea may be traced ex- 

 tending across the greater part of Southern Asia, through Asia Minor, 

 Persia, and Afghanistan, and along the foot of the Himalaya, even 

 to the Khasiya hills, east of Bengal. The mountain-area above the 

 level of the sea was at this time probably restricted, for the traces 

 of the ocean of that period have been found in Tibet, at a place 

 where a pass now rises to a height of 16,500 feet. At the close of 

 the nummulitic period, a general elevation seems to have taken place 

 over all Southern Asia, and the table-land of Afghanistan was finally 

 raised above the Southern sea, which, however, still swept over the 

 whole of the existing plains of India ; while the Caspian probably 

 extended over all the steppes of Western Tu.rkistan, to the foot of 

 the Hindu-kiish. To the north of the Himalayas, the Northern sea 

 appears to have covered the table-land of Tibet, occupying long 

 fiords or estuaries between the mountain-ranges, which had already 

 commenced to rise. 



By the middle of the Tertiary epoch the Siwalik Range had been 

 brought into its existing position, the whole of the great Tibeto- 

 himalayan system had been greatly raised, and the upward motion 

 extended to the basin of the Caspian, which sea was now separated 

 from that of Aral. But the Indian Ocean probably still covered 

 the northern plains of India, nor was it until long after that it retired 

 to its existing shores. Finally, the evidences of the diminution of 

 the Himalayan glaciers in the existing epoch, which are to be met 

 vdth at all parts of the chain, were attributed to the change of 

 climate that must have accompanied this last change of the marine 

 area, by which the conditions, becoming more continental, the sum- 

 mer temperatures would be raised, and the fall of snow diminished. 

 This, therefore, might have had the effect of causing the snow-line 

 and glaciers to recede, although the actual elevation of the mountains 

 had been inci'eased about 1000 feet. 



