204 VREDENBURG : SKETCH OF BALOCHISTAN DESERT. 



different from the great ranges that bear that name along the 

 southern flanks of the Himalayas ; the reason is obviously the different 

 physical conformation of the mountains. The Siwaliks in India 

 have resulted from the denudation of that colossal escarpment which 

 terminates the Tibetan plateau on its southern border, and which 

 overlooks the Gangetic plain. The enormous height of the mountains 

 and their geographical situation favour an abundant rainfall and 

 cause all the drainage to escape to the south of the ranges where 

 the permanent deposits resulting from their denudation have 

 accumulated all over the northern plain of India. Denudation had 

 set in actively for long ages before the tangential pressure that 

 folded the mountains had come to a standstill ; hence the deposits 

 accumulated on the northern edge of the alluvial plain have shared 

 in the last movements of upheaval, and their tilted strata now 

 constitute the sub-Himalayan ranges. 



In Baluchistan, just as in India, the tilted strata of the Siwaliks do 

 represent similarly the last effects of the earth-movements that raised 

 the numerous mountain ranges, and have now perhaps entirely- 

 ceased to act. But, instead of the gigantic and compact highland 

 of the Himalayan region, the ranges of much more moderate eleva- 

 tion form numerous strips of high ground separated by lowlying 

 plains. Moreover, although the aggregate thrust may have resulted, 

 as in the case of the Himalayas, in a movement along a roughly 

 north-to-south direction, yet the structure of the ranges shows that 

 the rocks have been forced over the depressed areas along both 

 margins, south as well as north, and the thrust has acted locally 

 at least in a south-to -north direction, the reverse of what is found 

 invariably along the Himalayas. It results from this that where a 

 rano-e runs between two plains it is skirted on either side by Siwalik 

 strata, dipping in either case towards the centre of the range, and 

 giving the section a sort of fanlike appearance. Being thus distri- 

 buted somewhat evenly right through the region, it follows that the 

 materials that have accumulated to form each outcrop have been 

 derived from areas of drainage which are very small compared to that 



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