ORDOVICIAN SYSTEM : LOWER NAUNGKANGYI STAGE. 



To the east of the NanrTu the Ordovician rocks are entirely 

 concealed by the broad band of upper Pal- 

 Eastern Ranges. geozoic and Mesozoic strata that forms a con- 

 tinuation of the plateau proper extending to the north-east through 

 Lashio towards the Salween. They reappear among the hill ranges 

 east of the plateau, where, as has been remarked before, the rocks 

 are thrown into more or less regular folds, in which the Plateau 

 limestones are included, and the outcrops of the strata exposed by 

 denudation, instead of occurring as isolated patches fortuitously 

 uncovered wherever the burden of overlying rock happens to have 

 been removed, form regular bands, which can be traced in many 

 cases by a mere inspection of the contours of the ridges and valleys 

 for considerable distances. It is not possible, for reasons that have 

 already been given, to follow these bands up continuously on the 

 ground, but the observer can generally predict within fairly narrow 

 limits, by noting the configuration of the ridges and spurs, where 

 each particular formation is to be met with, and by working across 

 the strike, which is usually possible because nearly every spur 

 has a path running along it, can fix their position with consider- 

 able accuracy. 



The lower Naungkangyi rocks as seen in these ranges present 

 some notable points of difference as compared 

 tera^ndlScLies^ 0 ' with their development on the western side 

 of the plateau. The limestones so frequently 

 met with there are entirely absent, and the formation consists of a 

 homogeneous yellow or buff • coloured sandy marl of soft texture, in 

 which the fossils occur as casts, and in so friable a condition that it 

 is only seldom that they can be collected. The most remarkable 

 feature of this band of rock is its persistence in general thickness 

 and character ; it is of no great thickness, probably not more than 

 two or three hundred feet, but it occurs in every section wherever 

 the base of the fossiliferous series is exposed, throughout these hills. 



The most northerly locality at which these beds have been found 



. is on the southern side of the range of hills 

 Outcrops north oi ,, » ,, .. 

 Mongyaw valley. north oi the JNam-yau valley near Mongyaw, 



a large village on the road from Lashio to the 



Kunlon ferry. This range lies beyond the limits of the map published 



with this Memoir, since this portion of the country is not included 



in the new edition of the quarter inch map issued by the Survey of 



India. The Naungkangyi beds lie along the axis of an anticlinal fold, 



