6 llcconls of the Indian Museum. [Vol. XIV, 



can slicivv ck'posit.s of tliis kind of .such magnitude, at Ic^ast in the open air. In the ordi- 

 nary " Karst " region the evaporation u.sually takes place as the water triekles into the 

 eaverns and hollows worn out of the rock, with the formation of stalactites and stalag- 

 mite ; but in the Shan States there are no open caverns in the great bulk of the lime- 

 stone, owing to its universally shattered condition, which causes the mass to settle down 

 as underground solution proceeds ; though in the superjacent, more compact, Permo- 

 Carboniferous limestones eaverns are common enough. Thus the carbonate of lime 

 which would ordinarily be deposited on the walls of the caverns and fissures is in this 

 region brought to the surface and thrown down in the open. The brecciated structure 

 of the rock also allows water to percolate freely through the mass in all directions, and 

 tiiis no doubt adds to the rapidity with which it is dissolved." 



One can watch the formation of rocks where the lime-laden water is 

 trickhng over masses of leaves and roots. At the head of the He-Ho 

 pass what appears at first sight to be a fossil coral-reef is actually in 

 process of formation owing to water dripping upon the roots exposed 

 when a bank of earth is washed away by heavy rain. The lime is depo- 

 sited in concentric layers round each root, the organic matter of which 

 gradually decays and disappears, leaving a hollow tube. On the 

 He-Ho plain Dr. Gravely found curious ridges of tufa running for 

 considerable distances some feet above the surface of the soil and 

 clearly representing the beds of now perished streams. They were full 

 of shells of the same species as those found in the peaty deposits. 



Even from this brief description, which should be read in connection 

 with the papers by La Touche and Middlemiss already cited, it will be 

 clear that the surface of the Shan Plateau has been, and still is, subject 

 to great changes with which the waxing and the waning of the Inle 

 Lake are intimately connected. 



Origin and History of the Lake. 



The lake belongs to the type known as solution lakes — lakes with 

 their basins hollowed out of limestone by the dissolving action of water. 

 A common feature of such lakes is the presence somewhere in their 

 bottom of a " sink " or deep pit down which the whole or a part of the 

 water is liable to disappear. No " sink " exists in the Inle Lake at 

 present, but the point at which the river that flows out of it disappears 

 underground may very possibly have, at one period, been beneath its 

 waters. I have not seen this place and can, therefore, only point out 

 again that a very large tract of country to the south of the lake must at 

 one time have been covered by its waters, and have been gradually 

 filled in by the two processes referred to above, i.e., by the deposition of 

 silt and the formation of peat, especially by the latter agency. 



The lake must thus at one time have covered a much greater area 

 than it does at present, and it must have been much deeper, though we 

 have no evidence as to the height to which its Avaters reached. It may 

 have been over a hundred miles long and several hundred feet deep. 

 Moreover it is by no means the only lake that once existed in the neigh- 

 bourhood. Indeed, superficial deposits in the emptied basins scattered 

 amongst the hills of the Shan Plateau make it evident that the country 

 was once a regular lake country. Some of the lakes must have dis- 

 appeared at a remote period, but others have dried up recently, perhaps 

 even in historical times. There are traditions which seem to point to 

 this having occurred at He-Ho. The deposition of silt and the form- 



