Chap. I] general description of rocks. 11 



of this outlier rest on a denuded surface of the older rocks, and have 

 been folded up with them in the same contortions. 



Although I have only mentioned this outlier as exhibiting the lowest 



member of the Sub-Himalayan series, it contains 

 Subathu group. . 



m itself a well-defined group or formation of con- 

 siderable importance, both in vertical thickness and horizontal extent, and 

 admitting of two or three sub-divisions, no one of which can be strictly 

 identified with beds of the higher groups to the south of it. These 

 statements will be appreciated when I say that the Nummulitic strata of 

 Subathu, which have so much contributed to bring this region into 

 notice, form but a portion of this outlier, — the lowest member of these 

 sub-divisions being thus the bottom beds of the whole Sub-Himalayan 

 series. The prevalent character of the Subathu beds is calcareo-argil- 

 laceous, — thick beds of silty clay, generally of subdued neutral colours, 

 of very fine texture, and weathering in splinters, both acicular and 

 sub-cubical, very rarely shaly, or even laminated. The calcareous 

 element shows most frequently in irregular, sub-concretionary, earthy 

 beds, but sometimes in thin beds of pure hard limestone. There are also 

 occasionally beds of hard coarse grits or fine sandstones, of similar dull 

 colours with the clays. Among the upper beds of the sub-group thicker 

 runs of sandstone become frequent, having a prevailing purplish tint, and 

 with them occur strong beds of lumpy, gritty clays, of a bright and deep 

 red. The mineral characters of the bottom beds become soon completely 

 lost; the upper limit of this sub-group being thus transitional* and 

 arbitrary. I have usually taken it at the limit of fossils, which are 

 frequently very abundant, though ill-preserved, in the Subathu beds, but 

 wanting (as far as my research extended) in those above. These lowest 

 beds are nowhere better exposed than at Subathu, and in the khuds 

 (deep valleys) to the south and west. 



* It is not intended by the word " transitional" to convey any idea of locality or position 

 but simply a change in lithological character by gradual alteration. 



