PHYSICAL GEOLOGY. 



23 



The limestone plateaux of the Shan States differ in one im- 

 portant respect from the ordinary Karst, as such 

 Red clay of the plateau. . ' „ _ . 



plateaux are usually called, alter the well- 

 known district of that name in Carinthia. Instead of the broad 

 expanses of barren rock, with hardly any vegetation except the 

 ferns and mosses that find a habitation in the numerous fissures, 

 typical of a true Karstgebiete, we very seldom find, in the Shan 

 States, even a moderately sized area of bare rock visible at the 

 surface. The whole country is buried in an accumulation of red 

 clay, varying in thickness from a foot or two to as much as 30 

 or 40 feet, or even greater depths. It is only where a spring 

 issues from the limestone, and has washed away the clay as quickly 

 as it is formed, thus preventing its accumulation ; or in the beds 

 of the streams ; or, again, where the edges of harder strata of 

 lime-stone protrude through the covering, that the solid rock is 

 visible. 



One phenomenon, however, this region possesses in common with 

 all limestone plateaux. This consists in the 

 Swallow-holes and occurrence, often over large areas, of depres- 



Kesseltaler. 7 . 



sions in the surface, the drainage in which 

 passes underground. These depressions vary greatly in size, from 

 ' pipes ' of a few feet in diameter to ' swallow-holes ' (Plate 4) and 

 funnel-shaped ' punch-bowls ' (Brunnenformige and Trichterformige 

 Dolinen), of which the latter are by far the most common, and 

 from these to enclosed valleys several miles in length and breadth, 

 traversed by running streams (Kesseltaler) (Plate 3). 1 



The smaller ' punch-bowls ' are usually found in greatest number 

 t along the crests of limestone scarps, where the 



water finds an easy outlet on the face of the 

 cliffs, as, for instance, along the edge of the great scarp that runs 

 south from the railway at Kyauk-kyau, near Nawnghkio, to the 

 Nam-Tu. In other cases they have no obvious connection with any 

 scarp, and then are generally of larger dimensions. A large numbet 

 of depressions of this nature occurs on the wide plateau lying south 



1 There seems to be no good equivalent in English for the German term ' Kcsseltal 1 

 as applied to a limestone district. The translation ' caldron-' or 'subsidence valley 

 has been used to denote a phenomenon of a different character (Quart. Jour. Gcol. Soc, 

 Vol. LXV, p. 'ill), ,i subsidence caused by a single encircling fault; while the Knglish 

 torm 'Devil's punch-bowl ' applied to the comparatively small hollows oi this kind met 

 with on the chalk downs is hardlv appropriate in connection with a valley several miles 

 long and w ide. 



