HISTORICAL SUMMARY. 



363 



of the Plateau Limestone are seen inclined at a high angle or 

 even vertical, but the strata are quickly bent into an almost 

 horizontal position, and between the base of the scarp and Wetwin 

 are found everywhere with a moderate inclination towards the east. 



Several other scarps of this kind are to be met with on the 

 -.if plateau, and are so uniform in character that 



mcipa aut scarps. ^.^ ^ necessary to describe them all. 



At either end they begin with an almost imperceptible roll in the 

 limestone, followed, as the subsidence increases, by a definite break 

 in the surface and a wall of cliffs. In many cases rocks of dif- 

 ferent formations are thus brought into contact, wherever the throw 

 becomes considerable ; as for instance, the Wetwin shales at the 

 base of the scarp north of that village ; the red Namyau sand- 

 stones at the base of the long line of scarp that bounds the north- 

 ern side of the valley between Namhsim and Hsipaw ; and the 

 same rocks at the base of the scarp that runs from near Onghkok 

 (F 3) on the Nam-Tu below Namhsim to Pongwo (E 3) (Plate 10). 

 Of a similar kind is the fault in the valley of the Nam-Tu between 

 Htengnoi and Tong-ang, which has brought down against the 

 Plateau Limestone and preserved a wedge-shaped mass of Napeng 

 beds and the red sandstones overlying them. 



In some cases the line of the fault is marked by a series of hot 



or tepid springs. Such springs occur on the 

 Hot springs. . . . piiiir 



eastern and. southern sides ot the block ot red 



beds south of the Nam-Tu at Hsipaw ; one near Pengwai and sev- 

 eral between Na-kang and Loimawk (F 2), while a very important 

 one is to be seen at Nam-6n (Shan, Water-hot) at the point where 

 the continuation of the Loimawk fault would cross the north-south 

 fault running from Hson-oi to Pangsam (E 3). The salt spring of 

 Rawgyo, to which reference has already been made (p. 342), is 

 situated on the Namhsim fault, and the salt is probably derived 

 from the red beds which are there brought down against the Plateau 

 Limestone. 



There must be many ot these faults which do not betray their 

 , , . , . , , presence by a visible scarp, either because the 



Lashio nut springs fault. x * . . * . 



rocks on either side have been removed to 

 the same extent by denudation, or because they are not of suffi- 

 cient throw to bring rocks of different composition into contact 

 with each other. Thus the fissure on which the great hot spring of 

 Lashio is situated does not form a scarp, and would not be recog- 



