34 GEOLOGICAL HOTES ON ASSAM. 



was a g-eneral case. Such^ however^ is very far from being tlie fact. 

 Below the station of Cherra other rocks are exposed in complicated 

 variety beneath the cretaceous deposits. In descending- into the deep 

 eastern valley by the principal path from the native village of Cherra, 

 a fine-grained granite, a conglomeratic schist, a hornblende-schist, 

 are found in the undercliff ; about the bottom a trap is seen exactly like 

 that of the Kalapani. Coarse, clear, porphyritic granite also occurs. 

 On the path leading up from the same valley to the Cuteherry, at the 

 station of Cherra further to the south, a green, subschistose quartzite is 

 almost the only rock seen. The sections are too covered to show the 

 relations of these subjacent rocks. The elevation of the junction here, 

 as well as the locality itself, is between that of the other two positions 

 in which the contact is described. 



The whole stratified series at Cherra may for convenience of de- 



c ,, scription'^ be divided into three groups, locally well 



Bottom rocks of the ^ b r j j 



Cherra series. marked by physical features. The bottom-group 



varies much in kind and in thickness. In the section under Cherra 

 station a massive conglomerate is conspicuous. It is coarsest at its base, 

 passing up into the sandstone of which it is but a modification — a porous, 

 coarsish, quartzose, non-micaceous rock, of pale yellowish and brownish 

 tints according to the condition of the felspathic earth it contains ; it 

 is closely of the same character as all the overlying sandstones. In 

 these sections chloritic grains are quite exceptional throughout the whole 

 series; I only noticed them very locally in the conglomerate. Below 

 Mawmluh to the west the bottom-rock is very much the same as at Cher- 

 ra, perhaps less conglomeratic. Along the southern edge of the rang-e, 

 although the distance is but two or three miles, a great change is ob- 

 served. The conglomerate is scarcely represented at all. When this rock 

 exists it can scarcely fail to be seen in the debris, if not in section. On 



* Oldham. Mem. Geological Survey, India, Vol. I., pp. 117 — 120. 



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