igoS.] THE PHYSICS OF THE EARTH. 231 



outside of these mountains there still remain trough-like depressions 

 where the Indus, Ganges and Brahmaputra now flow. The under- 

 mining produced in raising the Himalayan embankment still shows 

 in the valleys to the south, though the sea has receded; and the 

 great earthquake belt south of the Himalayas still discloses to us the 

 nature of the forces which produced this mighty uplift. 



The following critical passages by General Strachey are also of 

 decided interest : 



"The great peaks are, with few exceptions, composed of schistose rock, 

 though granite veins may be seen in the mountain faces to very great ele- 

 vations ; one of these exceptions is the great peak of Kamet in Kumaon, 

 which rises to about 25,000 feet in what appears to be a mass of grey granite. 



" Passing to the north of the line of great peaks the metamorphosed 

 schists are suddenly replaced by slates and limestones, which are in many 

 places highly fossiliferous, exhibiting what appears to constitute in the 

 aggregate a fairly continuous series from the Lower Silurian to the Cre- 

 taceous formations, though the complete sequence has not been observed in 

 any one locality. The western region of the Himalaya alone has been suf- 

 ficiently explored to admit of any positive statements, but the indications 

 gathered from such imperfect accounts and other data as exist relative to 

 the eastern parts of the mountains leave little doubt that the change ob- 

 served in the west on approaching and entering Tibet holds good on the 

 east also, and that the general physical features of the whole tract are much 

 alike, though doubtless with many differences in detail. 



" The fossiliferous strata of western Tibet are continued, though per- 

 haps with some breaks, to the Tertiary period. In certain localities num- 

 mulitic rocks, probably Eocene, have been observed, and from the great 

 alluvial deposit which forms the plain of Guge, already noticed, the remains 

 of mammals, apparently of Siw^alik age, have also been obtained. Among these 

 were bones of the elephant and rhinoceros, the existence of which, in the 

 present condition of these regions, would be wholly impossible ; so that 

 there is no room to doubt that these deposits have been raised from a com- 

 paratively low level to their existing great elevation of upwards of 15,000 

 feet, since they were laid out. As in the case of the plain of India, we 

 here, too, have no complete proof of the origin of these great nearly hori- 

 zontal deposits, but it seems clear, from the materials of which they are 

 formed, that they must have been laid out by the water, either by the sea 

 or some great inland lake. They are largely composed of boulder deposits, 

 and large boulders are strewed over the surface imbedded in the ground in 

 a manner that seems only explicable as the result of the action of a con- 

 siderable body of water. 



" Several lines of granitic and eruptive rock occur in western Tibet, of 

 which all that need here be said is that the}- appear all to be older than 

 the Tertiary alluvium, but some of them are possibly contemporaneous with 

 the nummulitic and older formations." (Ency. Brit. p. S28.) 



