322 LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



feet, and about Loi ling (8,771 feet), must have been affected in 

 the same manner, though in a minor degree, by the refrigeration of 

 the climate, with a similar result. 



(2) Recent deposits. 



There are four categories of recent deposits that deserve men- 

 . fi ^ t _ tion, (a) the red clays of the limestone area, 



(6) travertine or calcareous tufa, (c) iiver allu- 

 vium, and (d) the peaty deposits of the uplands. 



(a) Surface Clays. 



One of the most striking features of the plateau country 

 is the universal mantle of red clay which is spread over the limestone. 

 When one ascends even the smallest elevation above the cultivated 

 straths that border the streams, red is the prevailing colour that meets 

 the eye, wherever the soil is exposed, and it certainly adds much to 

 the picturesque character of the scenery. The colour is a bright 

 Indian red, sometimes with a slightly orange 



Lithological characters. n _ 1,1 • i-i, 



tint when dry, but becoming much darker 

 when wet. On the open plateau the clay contains little or no 

 sandy matter, and is of a stiff, tenacious nature, very slippery 

 when wet with rain. 1 It is usually filled with pisolitic nodules of 

 iron oxide, ranging from the size of a pea to that of a hazel nut, 

 resembling the nodules of which some varieties of laterite are built 

 up. In fact it is not improbable that the red clay owes its 

 growth to a process similar to that to which the origin of laterite 

 is generally attributed, the decomposition of the underlying rock ; 

 but in this case the resulting product is less consolidated, owing 

 perhaps to the absence of siliceous matter from the limestone. It 



corresponds rather to the ' Terra Rossa ' of 

 * Tcrrti Rossft* • ■ 



south-east Europe, 2 where it is largely devel- 

 oped in the limestone tracts (Karstgebicte) of Istria and Dalmatia : 



1 The stiffness of this clay has a peculiar effect upon the Shan roads, which I do not 

 remember to have noticed elsewhere. During the rainy season the feet of the bullocks, 

 which are commonly used as pack animals, poach the clay into a series of parallel trenches 

 running transversely across the roads, leaving solid bars between them which remain 

 throughout the dry season and form a most uncomfortable road to travel over. It 

 resembles nothing so much as an abandoned railway, from which the sleepers have been 

 recently removed. 



2 Walther von Knebel, Eohlenkunde mit Beriickeichtigung der Karstphanomene 

 Di* Wissenschaft, Heft 15, p. 29. 



