56 OLDHAM: THK STRUCTURE OF THK HIMALAYAS, ETC. 



on the north and a floor sloping gradually upwards to the south. 

 Table No. 16 gives the deflections due to a trough 200 miles in width, 



Table 16.— Deflections due to a trough 200 miles broad, 20,000 jt. 

 deep diminishing to nothing; density '8 of average rock. 





Station. 



Deflection. 



Station. 



Deflection. 





— . — ~ — ' ■ 









40 



15 



+ 8 





1 



— 



14 



16 



+ 7 





2 



— 



7 



17 



+ 7 





3 



— 



3 



18 



+ 7 





4 









10 



+ 7 





5 



+ 



2 



20 



+ K 





6 



+ 



4 



21 



+ 3 





7 



+ 



6 



22 



+ 2 





8 



+ 



7 



215 



+ 1 





9 



+ 



8 



24 



+ 1 





10 



+ 



S 



25 



+ 1 





11 



+ 



8 



2li 









12 



+ 



8 



27 









13 



+ 



8 



28 









14 



+ 



8 



29 







with a vertical northern side 20,000 ft. in depth and the floor sloping 

 gradually upwards to the surface ; in this case the calculation is 

 extended to a distance of 100 miles beyond the limit of the trough 

 to indicate the rate at which the effect of such a trough would die 

 out as the southern limit of the Gangetic alluvium is left. In 

 every case the trough is supposed to run east and west, and the 

 northern limit is assumed to coincide with the southern boundary 

 of the range, or with station ; this enables the effect to be con- 

 veniently stated in the tables, and by combination, with reversal 

 where necessary, of two or more of the cross sections given in the 

 table, an approximation to any cross section which need be con- 

 sidered can readily be built up. Further, although the deflections 

 have only been calculated for certain depths of trough, they 

 may be determined for other depths by interpolation or extrapola- 

 tion, which will not introduce any material error, at any rate between 

 the limits of 5,000 and 30,000 feet of maximum depth. 



In these tables two features are noteworthy ; one, that in every case 

 we have a high northerly deflection at the foot of the hills, which 

 decreases rapidly both northwards and southwards, but more rapidly in 

 the latter direction, especially in the case of a floor sloping upwards 

 to the south ; the other that, at a distance from the edge of the hills 



[ 204 j 



