1865.] Tlie Geological Survey of India. 341 



fossils referable to the Silurian, Triassic, and Jurassic ages. Thus 

 the highest passes into Tibet, at elevations of 20,000 feet, are 

 formed of slates and limestones, containing Asaphus, Cybele, Cyrtho- 

 ceratites, and other Silurian forms ; beyond these are limestones, with 

 Ceratites of the Muschelkalk, while beds with organisms resembling 

 those of the Lias, Cornbrash, and Oxford clay follow in succession. 



The whole of these formations of the two groups have undergone 

 an extraordinary amount of disturbance. The beds are often vertical, 

 and even inverted. In other cases they are broken by faults, and 

 with such physical and stratigraphical obstacles to contend against, we 

 cannot but consider that much credit is due to the author for disen- 

 tangling the complicated structure of these rocks. 



The " Subathu " beds are followed by the " Nahun " and " Si- 

 valik " rocks, which are somewhat similar to each other in character, 

 being principally sandstones and conglomerates of great thickness ; 

 they have, nevertheless, a very marked line of division. This is 

 illustrated by the section in the Narkunda which forms the frontis- 

 piece to the memoir. The upper series of sandstones seems to have 

 been deposited against, and upon, a denuded surface of the lower 

 series, which apparently formed a line of high cliffs and hills facing 

 the open sea to the south. The break thus shown between the two 

 groups indicates a second period of elevation in the Himalayan 

 range. The Sivalik beds are in turn succeeded unconformably by 

 the nearly horizontal strata of the Ganges valley. 



It would, of course, be hazardous to draw any general conclusions 

 regarding so comprehensive a subject as the upheaval of the highest 

 range of mountains in the world, from an examination of a limited 

 portion of the entire length; and Mr. Medlicott very properly 

 qualifies his remarks on this topic with the proviso, that they are open 

 to subsequent alteration. Nevertheless, his views are novel and well 

 supported. The usual opinion, founded on the fact that the Tertiary 

 sandstones of the Sivalik group dip towards the " Himalayan " beds, is 

 that these older rocks are upheaved along an enormous fault or 

 fracture. The author, however, seems to consider that the direction 

 of the dip is due to foldings arising from enormous lateral pressure, 

 and that the line of contact is not strictly a fracture,|but an original 

 margin of deposition. The discordances amongst the Tertiary beds 

 themselves are evidence of a succession of elevations at intervals ; 

 and it would appear that the whole of the formations along the flanks 

 of the mountains have, at a very recent period, been subjected to a 

 process of crumpling, caused, as the author supposes, by the falling in 

 to a certain extent of the entire mountain range. 



In the case of the memoir of Messrs. King and Foote, we have not 

 the advantage of a map.* The description of the district is, how- 

 ever, sufficiently clear to enable us to dispense, for the present, with 

 a document so essential to a thorough understanding of the subject. 

 There are, besides, several coloured longitudinal sections, which con- 

 vey at a glance an idea of the general structure of the country. 



* The map is expected to be published ere long. 



