LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



of the Nam-Pawng, between Hsipaw and the Loi Pan range of hills 

 (Plate 5). The drainage from these probably finds its way into the 

 Naai-Pawng. 



The cause of the extraordinary abundance of these depressions 

 seems to lie in the intensely crushed condition of 

 hok'sTncl punch-bowls! tue limestone, which will be referred to in greater 

 detail when this formation is under description 

 (see below, p. 93). As the underground solution of the rock proceeds, 

 the whole mass settles down, but more rapidly in those places where 

 the subterranean drainage finds a ready passage ; and since the rock is 

 in too shattered a condition to support its own weight, the caverns 

 which we would expect to find in a limestone tract are not formed, 

 but in such places the surface is constantly in a state of subsidence. 



The Plateau Limestone in the Northern Shan States is almost entirely 

 in the crushed condition mentioned above, and 

 • Caverns and natural consequently open caverns are of very rare 

 occurrence. The well-known cavern in the 

 Gokteik gorge, beneath the railway viaduct, is, as I have shown 

 elsewhere, 1 not hollowed out of the solid rock, but is roofed over 

 by a deposit of travertine adhering to the cliffs on either side. 

 There are several of these so-called ' natural bridges ' in the Shan 

 States, and in some cases the roof may be of solid rock. This 

 appears to be so with the one on the Nam-sam stream, about 

 three miles north-west of Hsipaw, though here also the rocks 

 at either end of the ' bridge ' are greatly obscured by deposits of 

 travertine. 



The band of Permo-Carboniferous (Productus and Fusulina) lime- 

 stone that is found at the top of the Plateau 

 ( arbuni"crous m Mmestone. Limestone does not seem to have been affected 

 to the same extent by crushing, but is more 

 compact and homogeneous in texture. This limestone usually forms 

 sharp pinnacles or tabular masses with vertical sides, scored with open 

 fissures which give them a characteristic rugged appearance, as seen 

 from a distance, and among these, no doubt, caverns would be 

 found b\ careful search. These limestones are not, however, greatly 

 developed in the Northern States, but are now the merest remnants of 



1 Nnte on the Natural Bridge in the Gokteik Gorge, Records, Geol. Surv. Ind., Vol. 

 XXXIII, J't. 1, p. 4<J. 



