84 LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



great, but uniform depth, judging from the homogeneous charactei 

 of the deposits over wide areas. The presence of the Ngwetaung 

 sandstones, and of bands of limestone in the western portion of the 

 area occupied by these deposits, and their greater thickness in that 

 direction, seem to indicate that the coast-line lay to the westward ; 

 and this conjecture appears to be the more probable, because no 

 deposition seems to have taken place over the area occupied by 

 the crystalline rocks to the north-west of the Shan States, through- 

 out the whole of the Paleozoic and Mesozoic periods. 



Consideration of the homotaxial equivalents of the lower Naung- 

 kangyi beds in other regions of the earth's 

 surface will be deferred until the whole of 

 the group has been described, but sufficient has already been 

 said to indicate that they correspond very closely with the 

 middle Ordovician rocks of the Baltic Provinces. 



Upper Naungkangyi Stage (Western Area). 



The strata now to be described have a very much wider dis- 



,.. , , tribution at the surface than the lower Xaung- 



Litholo£cical characters. . . - . . , . , 



kangyis, and may be said to constitute, after 



the Plateau limestone, the most important formation occurring 



in the Shan States. They consist of peculiar argillaceous shales 



and claystones often resembling lithomarge in texture, and present 



a great variety of colours, ranging from red through lavender, 



orange, and various shades of yellow to a pure white. In all 



cases they bear evidence of intense crushing, which has iesulted 



in the development of a kind of incipient cleavage, resulting. 



in many cases, in the obliteration of the original bedding planes, 



so that the term ' shales ' hardly describes them correctly. The 



rock, indeed, often presents the appearance of a mass of clay 



that has been passed through a ' pug mill '; and when broken by the 



hammer, the fracture has some resemblance to a ' slickensided ' 



surface. This compression has of course resulted in a general 



distortion of the fossils, as in the lower Naungkangyi beds. 



Two lithological varieties of these beds have been distinguished, 



one of which is found along the southern and 



Two types of strata. , , " _ 



eastern borders of the old lawng-rcng land 

 surface, comprising all the beds of this age to the west of Lashio, 

 which are of the variegated type described above ; while the 

 second is the predominating type in the Eastern ranges, consisting' 



