FROM UPPER BURMA AND THE SHAN STATES. 5 
ficial covering up to three or four hundred feet, according to the 
amount of denudation it has undergone. This mantle of red 
clay at one time certainly overspread the whole country, probably 
at a nearly uniform level, for patches of it, like raised beaches, 
are seen clinging to sheltered hollows in the black limestone 
ridges which rise through it in long parallel folds—remnants, no 
doubt, marking the ancient level of the red clay, as deposited in 
the quiet depths of an ocean or large lake. The underlying 
limestone, wherever exposed to view, is seen to have been worn 
into rounded hollows and projecting bosses, apparently by the 
action of water, at a time when it was exposed to denudation ; 
and, like limestone in other parts of the world, it is full of 
clefts, crevices, and caverns, communicating with each other to 
form subterranean channels into which a great part of the 
superficial drainage of the country disappears. 
The rainfall of the Shan plateaux has not yet been determined 
with any approach to accuracy, owing to the short period which 
has elapsed since the British occupation of the country, but it 
certainly considerably exceeds that of Upper Burma. From the 
few available records it may be roughly estimated that the 
annual fall in the Southern Shan States averages about sixty 
inches, the greater part being precipitated between the months 
of May and September, though occasional showers fall during the 
rest of the year. Still, the general aspect of the vegetation, 
especially the few species of ferns which are found, show that 
the climate is not persistently damp, and that in this respect it 
differs much from that prevailing in the lower valley of the 
Trrawaddy and in the Tenasserim hills. 
On quitting the border of the forest and entering the plateaux, 
the traveller is at once struck by the temperate character of 
the flora. Species of Ranunculus, Clematis, Viola, Polygala, 
Hypericum, and Swertia are common plants, while bushy Lespe- 
dezas, large flowering Asters, tall Labiates, and showy Ipomæas 
give the vegetation a more specially Asiatic character. Among 
the trees, oaks and pines are the most common and conspicuous. 
No less than nine species of oak have been collected; and this 
genus forms a considerable proportion of the trees in the upper 
part of the terai forest, as well as of the woods clothing the sides 
of the hill-ranges. The common pine of the Southern Shan hills 
is Pinus kasya, which extends from the Khasia hills in Assam 
to Martaban on the coast of Tenasserim. It never, so far as 1 
