146 



LA TOUCHK: GEOLOGY OK NORTHERN SHAN STATES. 



at the northern and southern ends of the dome, arching over the purple 

 Hwe Mawng shales forming its core. In the northern area a great 

 thickness of beds is exposed, and it is possible that the Namhsim 

 Sandstones, as well as the marls, are represented here, but this 

 tract of country has only been cursorily examined. A few frag- 

 ments of trilobites, probably of Encrinurus, were the only fossils 

 detected. At the southern end the rocks are very sandy and friable 

 in texture, breaking down easily into a loose sand forming rounded 

 pine-clad hillocks, among which it is hopeless to search for natural 

 outcrops. 



To the south also the beds are of this soft, sandy texture, and 



are very seldom exposed as solid rock. In 

 Hills east of Mong-Yai. J *\ 



tact, it would be almost impossible to map their 



boundaries with the Plateau Limestone, were it not for the circum- 

 stance that the common pine of this region, Pinus Khasya, does 

 not grow naturally on the limestone, but is found in great numbers wher- 

 ever the soil is of a sandy character. The outer edge of the pine 

 forests is therefore an excellent guide in mapping this boundary, 

 while the inner boundary with the Hwe Mawng beds may gene- 

 rally be detected with a certain degree of accuracy, since the latter 

 are harder, rise more abruptly from the low ground, and afford 

 numerous outcrops. In this way the upper Namhsim beds have 

 been traced along the western edge of the hills south of Loi Ling, 

 in South Hsenwi, up the valley of the Nam Ha, and along the 

 eastern edge of the hills in the valley of the Nam Pang. The 

 graptolites, Monograptus priodon and Cyrtograptus sp., already 

 mentioned (p. 129) as occurring at Kanlun in the valley of the 

 Nam Ha (Loc. 69, I 3), may perhaps belong to this horizon ; but 

 the rocks containing them are not of the same type as the marls, being 

 more shaly, with carbonaceous layers, overlying a band of hard 

 limestone. The exposure is quite isolated, and its position with 

 regard to the rocks above and below could not be ascertained. 

 In the band along the edge of the hills bordering the Nam Pang 

 fossils were found at two localities : — Lindstrcemia sp. and numerous 

 specimens of an undetermined bryozoan at Nampung, in the bed 

 of a stream of the name name close to the village (Loc. 62, J 3) ; 

 and the same coral, with fragments of trilobit s, probably Phacops 

 shanensis Keed, and brachiopods, all reduced to powder by the 

 leaching out of the calcareous matter from the rock, near the 

 small village of Ho-hko, not marked on the quarter inch map 



