HISTORICAL SUMMA R Y. 



353 



crosses the river below Mandalay and divides the range of hills 

 mentioned above from the plains of Sagaing and Shwebo. This 

 range is so narrow, and in common with the isolated knolls rising 

 from the alluvium on the eastern bank has been so deeply eroded 

 in recent times, that it is not surprising that no vestiges of the 

 Palaeozoic limestones now remain. 



Following the line to the north of west, across the plains of 

 , Upper Burma and the Chin-Lushai Hills, and 



Himalayan ' foredeeps. . . . . , . . 



leaving the Assam Range to the right, we meet 

 with no rocks whatever that we know to be of earlier than Ter- 

 tiary age until we reach the Punjab Salt Range, a distance of over 

 1,600 miles. This depression is the Himalayan ' foredeep,' already 

 alluded to, now filled with fluviatile deposits. No borings that 

 have yet been made have penetrated to the floor of this depression, 

 and in only three instances can we obtain any knowledge of the strata 

 h S It R ^ ia ^ ma ^ un derlie the alluvium and Tertiary 



deposits. One of these is the Salt Range it- 

 self, where a succession of strata extending from the Carboniferous 

 to late Tertiary has been brought up by a fault or series of 

 faults, following the line of the southern scarp, which cannot be 

 of earlier date than the deposition of the upper Siwaliks. Only 

 40 miles to the south of this fault-scarp, in the Kirana Hills on 

 the Chenab, the ancient rocks of the Indian Peninsula appear, prov- 

 ing that there is no inherent difficulty in supposing that marine 

 strata of the age of those exposed in the Salt Range may not be 

 concealed beneath the Ganges alluvium at equally short distances 

 from its southern edge, further to the east. 



The second instance is that of the Assam Range, along the 

 „,, , southern edge of which there also runs a sharp 



J ho Assam Range. . ° L 



dislocation. Here the oldest fossihferous beds 

 that are brought to light are of Cretaceous age, but a great thick- 

 ness of bedded traps, supposed to be the equivalents of the Raj- 

 mahal traps south of the Ganges, and of Jurassic age, have also 

 been involved in the upheaval. These are followed by limestones 

 and sandstones of Tertiary age, showing that here also the disloca- 

 tion took place in late Tertiary or more recent times. There are 

 no Carboniferous or early Mesozoic beds to be seen here, it is 

 true, but the sedimentary strata occupy a narrow strip along the 

 southern slope of the range, and extend to no great distance 

 across the plateau beyond ; while the composition of the Cretaceous 



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