RH/ETIC STAGE. 



285 



crystalline in structure and dolomitised, under the influence of 

 subserial denuding agents, indicated by the 



Conglomerates. , , . , , , . 



presence of sporadic beds of coarse conglomerate, 

 containing well-rolled pebbles of the limestone, as well as of the older 

 rocks underlying it. These conglomerates have all the appearance 

 of beach deposits, and may have been formed when the sea was 

 again advancing. 



When deposition again set in with the advance of the sea in 

 j . , h t Rhsetic times, the beds laid down were of a 

 10 og a , c e . . different character from those that had 



preceded them, and are very unevenly distributed. They are 

 also variable in composition, but the prevailing type is a yellow 

 or variegated, highly argillaceous shale or indurated clay, not 

 unlike the We twin shales in appearance. In places they are 

 impregnated with calcareous matter, and pass into clunchy, 

 sandy marls, or tough argillaceous thin bedded limestones. Beds 

 of a hard, dark blue limestone, indistinguishable, when it does not 

 contain visible fossils, from some of the Pernio Carboniferous limestones, 

 are interstratified with the shales, especially at or near the base 

 of the formation ; but though these, as seen in thin sections, are 

 crowded with fragments of shells, echinoid spines, and foraminifera 

 (Plate 15, Fig. 2), the fossils are only occasionally to be seen weathered 

 out on the surface, and these rocks have yielded nothing but a few 

 corals, and those barely fit for determination. 



The distribution of these beds is very capricious, patches of them 

 having been met with at widely separated points 



Distribution. ~ „ „, ~, n , , 



over the .Northern Shan States, lney have not 

 yet been found in the Southern States. Only one occurrence of them is 

 known to the west of the Gokteik Gorge, viz., at Kyaukkyan (Loc. 11, 

 D 3), at the point where the railway crosses the great fault scarp between 

 Hsum-Hsai (Thonze) and the gorge. This outcrop was discovered in by 

 Mr. Datta in 1900, 1 a short time after I had come upon another 

 small patch of the same beds at Kyinsi or Hson-oi 2 (Loc. 13, E 2). 

 close to the conflux of the NYunhsim and Nsirn-Tu rivers near Bawgyo 

 In the following year Mr. Datta discovered what has proved to be 

 the largest and most extensively developed occurrence of these beds, 

 the large area to the east and south-east of Napeng (Loc. 14, E 2, Locs. 

 15-22, E 3), a small village after which the formation has been 



l General Report, OeoU Surv. bid., 1899-1900, p. 109. 

 *lbid, p. 93. 



