INDIAN GEOLOGY. 137 



which is neither definitely Mesozoic nor definitely Kaino- 

 zoic, but is intermediate between the two. 



We now come to the last, and perhaps the most im- 

 portant of all the questions which will be referred to here, 

 viz., the origin and age of the Himalayan chain. The sub- 

 ject is fully discussed by Oldham in perhaps the most 

 interesting of all the chapters in the Manual; and this, 

 at least, is a chapter which no geologist should omit to 

 read. It is to Medlicott x that we owe our first conception 

 of the way in which the Himalayan chain grew ; but it was 

 the researches of Middlemiss 2 in Kumaun and Gahrwal 

 which put the matter on a satisfactory basis and laid the 

 real foundations of our knowledge of the process. 



From a geological point of view the Himalayas may 

 be divided into three zones which correspond more or less 

 closely with the great orographical features of the range. 

 The first is the Tibetan, which lies to the north of the chain 

 of snowy peaks ; and in this belt marine fossiliferous rocks 

 are well developed, but except towards the north-w T est end of 

 the range they do not extend to the south. The second is 

 the zone of the snowy peaks and of the Lower Himalayas to 

 the south of them ; and these are made up of crystalline 

 and metamorphic rocks, and of unfossiliferous sedimentaries 

 (believed to be Palaeozoic). And the third is the zone of 

 the Sub- Himalayas or foot-hills, which form the margin of 

 the range towards the Gangetic plain and which consist 

 entirely of Tertiary, and principally of Upper Tertiary, rocks. 

 It is the last zone which has been most carefully examined 

 and concerning" which we have the most accurate informa- 

 tion. The rocks which compose it are divided into : — 



Upper Tertiary or Siwalik, 

 Lower Tertiary or Sirmur. 



The Lower Tertiary commences with a group of clays 

 with some limestones and sandstones, in which marine 



1 Quart. Journ. Geo/. Soc, xxiv. (1868), p. 34 ; and Manual, first edition, 

 chaps, xxii., xxiii. 



2 " Physical Geology of the Sub-Himalaya of Gahrwal and Kumaun.'' 

 Mem. Geo/. Surv. India, xxiv., pt. ii. (1890). 



