370 a, 13. wynne on the physical 



Post-Tektiaky. 



21. A long interval of time, during which the whole surface of 

 this area underwent enormous changes as to form, followed the 

 latest Tertiary period on record. At the close of that period there 

 were tranquil waters, inhabited by crocodiles and tortoises &c, 

 depositing masses of fine saline silt upon the shore-like shingle 

 brought down from the Himalayan region. Then these great 

 mountains and the Salt Eange were formed, or still further elevated, 

 and the general level of the country where the Riwal-Pindi plateau 

 is now situated may have stood more than 2000 feet higher than it 

 does at present. This elevated region, too, may have been limited 

 to the south of the Salt Range by as definite a boundary as that of 

 any part of the southern face of the Himalayan region to the east- 

 ward. 



Much, if not the whole, of the plateau and its vicinity was again 

 covered with water after it had received its present general form, 

 and into this water, gulf, or lake-basin the great Himalayan rivers 

 continued to bring down much the same kind of mountain detritus 

 as they had done before ; beds of conglomerate were deposited and 

 banked up at tolerably steep angles in places. These occur even 

 on such lofty situations as now form the top of the Salt Eange and 

 mountain tops 2000 feet above the present bed of the Indus, south 

 of Attock. On these elevations, and near Kalabag, the well-rounded 

 crystalline pebbles are of the same kinds as those which the river 

 beneath still carries from its Himalayan regions. 



Besides showing the continuous denudation of some high lands 

 in the Western Himalayan region, the later pebble-beds of this 

 period bring the scene of that denudation nearer to the present dis- 

 trict, perhaps within it ; for the detritus, though still largely con- 

 sisting of quartzite, contains as well masses of limestone pebbles 

 derived from the waste of the Triassic and other limestones of this 

 outer Himalayan area immediately to the north. 



In the Rawal-Pindi plateau the pebble-beds, of quartzite and 

 limestone chiefly, are covered by thick horizontal beds of silt ; 

 beyond the first ridge to the north (the Cheta range) gravels, 

 formed mostly of syenitic debris, are also horizontally overlain by 

 coarse grey sand in massive beds, enclosing large subangular frag- 

 ments of similar crystalline rocks. This variety in the deposits 

 would indicate that the waters of the time lay in different basins 

 or gulfs, and received the drainage of different areas undergoing 

 denudation. 



Changes of level, as well as previous denudation of the ground, 

 may very possibly have been connected with the distribution of 

 these post-Tertiary deposits, and some of the coarser accumulations 

 may now remain where they were deposited by rivers ; change 

 of climate, too, might have occurred. Prom this or other causes 

 the terrestrial fauna of the Siwalik times seems to have almost 

 entirely disappeared from this neighbourhood, as well as all traces of 

 arborescent vegetation, though the calcareous cement of certain of 



