1875.] Glacial Action in the Naga Hills. 213 



deposits there is every reason for supposing to be the same as that of the 

 Japvo moraines, the result of a powerful river action, due to a heavy winter 

 snow-fall, — all the main sources of the Barak lying in lateral valleys of the 

 Kopamedza ridge at an elevation of 7 — 8,000 feet. 



The character of the valleys that drain away through Munipur and 

 eventually into the Irawadi, is intimately due to former effects of climate, 

 during the period the changes I have above described were going on. These 

 valleys and Munipur have at one time presented the appearance of a chain 

 of lakes, now dry, the only remnant in Munipur itself being the Loglak 

 Lake, now of small dimensions ; a description of one such tributary valley 

 will suffice for all, — and I am informed by Dr. J. Anderson that like char- 

 acters are to be seen in the country towards Yunan. On the water-parting 

 of the Irawadi and Surmah, one looks down on the Khongba flowing 

 with sharp bends through a broad almost level valley. The steep slopes 

 from the Koupru ridge on the west terminate some two miles from the 

 base of those on the east, and a very gradual nearly level surface of water- 

 worn detritus covers the intermediate ground, through which run four 

 streams from the ridge above-mentioned. 



The valley on the east is bounded by a low ridge of only some 

 300 feet above its bed, which gives off to the east spurs rising to 

 1000 feet. Further down the valley, 6 miles from the watershed at Kaital- 

 Mambi, a collection of detritus (mostly angular) forms a terrace about 50 feet 

 above the stream, and is the termination of the long talus given off by the 

 deep ravines on the flank of the Koupru peak, which here rises to feet 



some feet higher than the ridge to its north. This talus extends 



close up to the eastern side of the valley and undoubtedly at one time 

 abutted on its eastern spurs forming a lake above, subsequently drained by 

 the stream cutting its way round their present base, a process which would 

 have commenced directly the formation of talus from Koupru ceased with 

 the change into present climatic conditions. 



A sketch (PI. XII, Pig. 2) of the Kaital-Mambi lake bed from the 

 watershed is given in illustration of the above features. 



