NORTH CACHAR HILLS. 73 



colour, with occasional bands of fine shale. It is roughly horizontal, 

 but considerable disturbance is frequently seen in the finer beds. 



To the north-east of Haflong another small exposure of the 

 crushed shales occurs in the Phoiding valley; but otherwise, north 

 of Haflong, only massive sandstone, grey to buff in colour and 

 generally horizontal, is seen as far as the Lumding plain. 



At Boila, about 3 miles north of Mupa, there is a reported occur- 

 rence of limestone in a nala amongst the hills. I saw no trace of 

 any limestone band, but I had no time to examine the country. From 

 subsequent information, I have learnt that the exposure is a layer of 

 calcareous tufa, forming a low cliff in a nala bed. It is only a foot or 

 two in thickness, and it must come, I think, from a deep-seated 

 spring, as there is no limestone near this horizon. 



Several wells had been sunk in the neighbourhood of Hathikali 

 by the late Mr. F. Wilde, Executive Engineer of that district. From 

 figures, which he kindly gave me, it appears that the sandstone 

 reaches down to 50 or 60 feet below the ordinary river levels, and that 

 it is underlaid by blue clay-shale of unknown thickness. 



To the north of Hathikali massive sandstone is seen in all the 

 railway cuttings. In some of the sections thin partings of dark car- 

 bonaceous shale occur in it. The dip is usually roughly horizontal, 

 but here and there it changes to a steep southerly inclination. 



The sandstone dies out before reaching the Lumding plain, 

 where a few small exposures of the underlying, horizontal grey clay- 

 shale are seen. 



The geological 'plateau' of the Shillong hills evidently stretches 

 eastwards as far as Haflong, and the 'uniclinal 



Summary. 



flexure , which terminates the plateau along its 

 southern edge, turns north-eastwards, up the Jatinga valley, exposing 

 along its axis the crushed and contorted shale-series, and leaving the 

 overlying sandstones horizontal and undisturbed to the north, but 

 dipping down steeply along the Burrail range to the south-east. 



Mr. H. B. Medlicott has already noted this sudden turn of the 



( 73 ) 



