136 LATOUCHE: GEOLOGY OF NORTHERN SHAN STATES. 



A traverse across the valley of the Nam-Tu from east to west, 

 t .. t . in the neighbourhood of Lilu, brings to light 



Lilu overthrust (Sec- & . . ' ° 6 



tion IV, Plate 23, and one of the most interesting structural features of 

 Plate 22). ^ geology of this region, which has been alluded 



to before (p. 55), but a full account of which I have kept back until 

 I had reached the description of the Namhsim Sandstones, since these 

 rocks have played a conspicuous part in elucidating the structure 

 referred to. Descending from Nammo village (F 1), at the edge of the 

 fairly level plateau extending northwards from Hkawnghsa, on the 

 east side of the gorge, we first climb down a precipitous scarp formed 

 of the Namhsim Sandstones, which here attain a thickness of about 

 2,000 feet. Near the base of the scarp we come upon the grap- 

 tolite band of Panghsa-pye, — -which is not well exposed, but may be 

 found on the path leading along the edge of the river about a mile south 

 of Lilu ferry (Loc. 59), — and beneath this the purple band, which 

 has been traced at intervals along the river bank as far north as Ta- 

 pangtawng ferry. All these beds dip to the east at an angle of 

 about 30 degrees. In the bed of the river, at and just above Lilu, some 

 strong bands of limestone are exposed, and immediately beneath these 

 the variegated shales of the upper Naungkangyis, also dipping in 

 the same direction, and forming a dip slope on the western bank 

 extending up the spurs on either side of the deep ravine which joins 

 the gorge of the Nam-Tu at this point. If now we ascend the spur on 

 the southern side of the ravine, instead of finding a regularly 

 descending section through the lower Naungkangyis to the Chaung- 

 Magyi rocks of the hills beyond, we pass directly, after surmounting 

 the first steep rise, on to sandstones exactly similar to those forming 

 the scarp on the eastern bank, and dipping steeply to the east at angles 

 of 60° or more, while these sandstones are found to contain speci- 

 mens of Orthonota, etc., and therefore belong to the Namhsim form- 

 ation. Continuing along the spur to the peak, 6,019 feet, im- 

 mediately south of Tawngma, the dips again flatten out, and the 

 sandstones, here very coarse and felspathic, are seen resting directly 

 upon the Chaung-Magyi rocks, on the western slopes of the Tawng- 

 ma peak, the Naungkangyis being entirely absent. At first it seemed 

 as if the structure might be explained by simple overlap of the 

 Naungkangyis by the sandstones, but the high dips at the crest 

 of the spur could not be accounted for in this way ; moreover, 

 there is no question but that the sandstones do actually dip beneath the 

 Naungkangyi beds. The true explanation is, I think, revealed 



