48 MEDLICOTT, SHILLONG PLATEAU. 



opinion^ the argillaceous rocks underlie the quartzites. The only area in 

 which I have seen the former well exposed is in the run of low ground 

 along the west flank of the Maophlong ridge ; indeed^ I cannot he 

 certain that the rocks here exposed occur anywhere in the region I have 

 examined to the east of this line ; subordinate runs of schist do show 

 locally in the valleys to the east^ but they may be associated immediately 

 with the quartzites. It is certain^ however^ that the same quartzites 

 occur again to the west^ within the main area of the schists. 

 Along the west flank of the Maophlong ridge^ there are many continu- 

 ous sections seen across the strike of the rocks at the junction of the 

 quartzites and schists. All the strata are nearly vertical,, so that a slight 

 tilt on either side produces opposite underlies and opposite superpositions. 

 Eor many miles the junction runs in a steady north-north-east course 

 corresponding to the strike of the beds. The quartzites of the ridge 

 afiect a very general easterly underlie ; and the same prevails at the 

 junction and in the slates or schists near it. This is the most positive 

 fact upon which I accept the quartzites as the younger member of the 

 series. Elsewhere also, where more earthy rocks are exposed, it is in the 

 valleys, and apparently underlying the quartzites. 



In the middle region, about Maobelarka and Laisoplia, a thick band 

 of conglomerate is very largely exposed associated with the quartzites. 

 It presents like characters everywhere, though apparently of variable 

 thickness ; it is almost exclusively made up of quartz pebbles, of four 

 inches diameter and under, but pebbles of coloured quartzites also 

 occur. It may be presumed to belong to one and the same band; and 

 the position of this band can be clearly fixed. For several miles along 

 the Maophlong junction, this conglomerate is the rock in contact, forming 

 the base of the quartzite group. It is about 100 feet thick; and the 

 lower portion is decidedly coarser than the upper, and has a more earthy 

 matrix. The variability and local character of the conglomerate is also 

 well seen on this line : although steady and conspicuous for some miles to . 



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