230 SEE— FURTHER RESEARCHES ON [April 24, 



which would necessarily have been followed by rupture or crushing along 

 lines of least resistance, and the movements on such lines are marked by 

 the great mountain ranges that traverse the surface. A dislocation of the 

 solid crust of the earth once having taken place, it would probably continue 

 to be a line of least resistance ever after, and a succession of movements 

 during past geological periods may thus be reasonably expected along such 

 lines. Somewhat in proportion as the disturbing forces are intense, and the 

 thickness of the crust on which they act is great, will be the tendency 

 of the lines of rupture to be continuous for a considerable distance; 

 and as the disturbed area is extended in its dimensions, the probability will 

 increase of a repetition of a series of similar dislocations on lines approxi- 

 mately parallel to, or at right angles to, one another and to the line on 

 which the greatest compression and consequent tension take place. In a 

 disturbed area, one transverse dimension of which is sensibly greater than 

 the rest, the longitudinal ruptures will predominate in the interior and the 

 transverse towards the borders. Almost all mountains give indications of 

 having been shaped by forces thus related, and to the action of such forces 

 may the main characteristics of the structure of the Himalaya, and the 

 arrangement of its ridges and valleys be attributed. Whatever may be the 

 power of rivers in general as instruments of erosion, and whatever effect 

 the Himalayan rivers have had in removing the fragments of the rocks over 

 and among which they took their courses, it is hardly possible to doubt 

 that their main directions were determined by the anterior lines of dis- 

 location which opened up hollows down which they could flow, and which 

 must invariably have been accompanied by a destructive and crushing action 

 on the rocks along them, which has enabled the waters the more readily to 

 sweep away the obstacles in their path. The parallelism of many of the 

 great Tibetan and Himalayan rivers for hundreds of miles together, and 

 such mountains, seems wholly inexplicable in any other manner." (Ency. 

 Brit., p. 828.) 



This account is quite clear and satisfactory, except that part of 

 it which deals with the cooling and contraction of the globe. Here 

 General Strachey has made the best of a very inadequate 

 hypothesis. 



Just as the Andes were formed by expulsions of lava from under 

 the Pacific, so also here the Himalayas were formed by a corre- 

 sponding movement due mainly to the Indian Ocean, which has also 

 raised high mountains along the eastern border of Africa. We can- 

 not yet give all the details of the Himalayan development, but in 

 general it is evident that it was similar to that of the Andes. The 

 uplift of the great plateau of Tibet corresponds to that of Titicaca. 

 And the parallel ranges of the Himalayas originated by the usual 

 process of the folding up of successive sea trenches. On the 



