114 OLDHAM: THE STRUCTURE OF THE HIMALAYAS, ETC. 



is not only narrower to the north "of Gogipatri, but probably 

 shallower also ; as suggested by the inliers of rock in the Karewa 

 region to the west, and in the alluvium east of Srinagar. 



The unknown amount to be attributed to this cause makes it 

 impossible to determine the amount or direction of the residual 

 of deflection, if the alluvium is taken out of consideration ; but the 

 observations do throw' some light on an interesting point of geo- 

 logical structure, for they enable us to form some estimate of the 

 depth of the depression of the valley of Kashmir. If we take the 

 difference in the deflections to be entirely due to the effect of 

 the alluvium we find that this is 12" in the meridian, which is 

 equivalent to about 17" at right angles to the direction of the 

 boundary of the alluvial deposit, and this, adopting the same 

 density of deposit as in the Gangetic trough, would necessitate 

 a depth of about 10,000 feet, or more. The estimate must be taken 

 as very approximate, and subject to several qualifications, the 

 most important of which are, firstly, the fact that the alluvium 

 will not be altogether without effect at Gogipatri and, as the estim- 

 ate is of a difference, this would necessitate an increase in the 

 absolute depth ; and secondly, the possibility that the southerly 

 attraction of the Pir Panjal range may be greater at Poshkar 

 than at the other station, thus lessening the amount of the 

 difference to deflection which should be attributed to the effect 

 of the alluvium, and so diminishing the thickness to be attributed 

 to it. These two qualifications, therefore, introduce corrections 

 in opposite directions and, as it is probable that both must be con- 

 sidered, they will, to a certain extent, neutralise each other, yet 

 after making every reasonable allowance, there remains the con- 

 elusion that the depth of the depression under the valley of Kashmir 

 is of such an order of magnitude as to bring its floor down to, if 

 not below, sea level. 



We can now summarise the separate conclusions which have 

 been reached, and attain an understanding of the general distribu- 

 tion of the compensation of the Himalayas. In the central part 

 of the range the compensation is in excess of the load which it is 

 supposed to support ; in the outer Himalayas, at a distance of 30 

 to 40 miles in from the edge of the hills, it is in very considerable 

 defect ; and somewhere between these two regions must come a 

 tract where the compensation and topography are in adjustment 



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