ORDOVICIAN SYSTEM : LOWER NAUNGKANGYI STAGE. 



73 



are interstratified with these beds in the neighbourhood, and 

 extend along the base of the ridge to the north and south, 

 but they have not yielded any recognisable fossils. Traces 



of argentiferous galena have been found near 

 m ine PUted silver - lead Taunggaung in the northern extension of 



these limestones, and a small shaft had been 

 sunk at the spot, but it does not appear to have reached any consi- 

 derable depth, and was probably put down by Chinese prospectors. 

 The limestones and marls extend eastwards from the base of the 



Ngwetaung ridge for several miles to Sakangyi, 

 Fossils, Taungkyun. , ° e , , s , , , , A . bJ ' 



but the whole oi the ground hereabouts is so 



covered with jungle that exposures are rare, and of very small 



extent. A short distance south of Taungkyun (Loc. 87, B 5) 



some pinkish brown sandstones occur, crowded with specimens of 



Orthis (Dalmandla) elegantvia Dalman, a well-known fossil of Cara- 



doc age ; the peculiar weathering of the rock in which these fossils 



occur has already been referred to (p. 67). 



Along the eastern side of the valley of the Kyetmaok stream 

 above Taunggaung the limestones can be traced, forming a line of 

 conspicuous cliffs, and overlying the Chaung-Magyi rocks which are 

 f ^ brought up by a fault running from north to 



teau^Sectionjsfl, II, ill, south along the floor of the valley. The lime- 

 Plate 23). stones disappear on the high ridge overlooking 

 Aunglok, (B 4), between that place and Memauk, being probably over- 

 lapped by beds of Silurian age, but they appear again along the lower 

 slopes of the lofty scarp forming the western edge of the plateau, east of 

 . the Chaung-Magyi or Nam Pek river. Fossils were 

 collected from some sandy beds weathered out 

 from them between 600 and 1,300 feet above the valley, on the path 

 leading up the scarp from Kyaukmo to Kyaukgyi, including Rafines- 

 quina, Orthis elegantula, and Cystidean plates (Loc. 80, B 3). Kyaukmo 

 is the site of a magnificent waterfall, which descends the whole height 

 of the scarp here, about 2,000 feet above the valley, and is clearly 

 visible from the Irrawaddy in clear weather (Fig. 4, p. 124). Its posi- 

 tion is shown on the geological map attached to Dr. Oldham's account 

 of the geology of the country north of Mandalay, published as an 

 appendix to Yule's narrative of the Mission to the Court of Ava in 

 1855 (p. 350). Beyond this the limestones have been traced to the 

 north as far as Nankatlia (B 3), but further on the jungle is so 

 dense and trackless that they could not be followed up without 



