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LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



shown to belong to a much later date than the limestone, and 

 to be of either Rhaatic or lower Jurassic age. 1 In fact, the fos- 

 siliferous part of the rock seems to be a coating of calcareous 

 tufa or travertine, deposited in Rhaetic or Jurassic times on the 

 edges of a ' sink-hole ' or ' pip i ' in the limestone while the centr? 

 of the depression was being filled up by silt, on which the Crustacea, 

 etc., lived. 2 



In the main area of these rocks, to the east and south-east of 

 Napeng, they are frequently and highly dis- 

 ^ Local disturbance of turbed and contorted in a most i rregu lar man- 

 ner. The beds are often horizontal or only 

 slightly tilted for a space, but within a few yards they may be 

 violently folded and crushed, as if they had been masticated between a 

 giant pair of jaws or passed through a ' pug-mill.' This contortion 

 of the strata is too irregular to be ascribed to a general earth thrust ; 

 and I think that a simple explanation of it may be found in the 

 gradual underground solution of the limestone floor on which the 

 formation rests, which has caused the shales to settle down in some 

 places while remaining undisturbed in others. Mr. H. B. Medlicott 

 has described, and explained in the same manner, a similar phen- 

 omenon at Chen a Punji in the Khasi Hills of Assam, 3 where upper 

 Tertiary sandstones and shales, overlying a land of nummulitic 

 limestone, have been let down and broken up by the dissolving 

 away of the limestone beneath. Then again, if I am correct in 

 thinking that the shales were accumulated in a depression in the lime- 

 stone, it is not at all unlikely that the floor of the hollow was very 

 irregular, and that when the rocks were again exposed to denu- 

 dation, a good deal of slipping took place, which would account 

 for much of the disturbed appearance of the beds. 



The discovery of the Napeng fauna in the first instance aroused 

 f th f f a cons iderable amoun t of controversy, echoes 

 Age oft e ormahon. ^ w hich Wl \\ be found in the General Reports 

 for the years 1899 to 1903, among the officers of the Survey regard- 

 ing the age of the beds. When Mr. Datta and I, the one at 

 Kyaukkyan and the other at Kyinsi (Hson-oi), first came upon this 

 fauna, we were both struck by its apparently Mesozoic facies ; 



1 Miss M. Healey, The Fauna of the Napeng Beds or the Rhsetic Beds of Upper 

 Burma ; Pal. Indica, New Series, Vol. II, Mem. No. 4, p. 87. 



2 On my last visit to this locality, in December 1906, none of these fossils were to 

 be found. In the few years that had elapsed since the rock was exposed by the cutting 

 made for the railway every trace of the old travertine deposit and of the fossils contained 

 in it had been removed by weathering. 



3 The Coal of Assam; Memoirs, Oeol. Surv. Ind., Vol. IV, p. 424, 



