112 SPOLIA ZEYLANICA. 
plateau beds are extremely pervious to water. The sedimen- 
tary beds, though less so,* are infinitely more pervious than 
the crystalline rocks. Consequently rain water which passes 
freely downwards through the plateau deposits soaks through 
the sedimentary beds and tends to collect upon the rocks 
below, making its way down the slopes of the ancient turtle 
backs to the bottom of the buried valleys. Somewhere along 
the main line of flow the surface of the country is bound to 
cut the water table, for meanwhile subaerial denudation 
will have been at work ploughing runnels and small streams 
in the plains, or, failing that, the water table, kept up by the 
beds below, will be cut at the coasts if the country has been 
elevated at all. And so a spring starts. The gradual crumb- 
ling in the beds above the source of the spring opens the way 
for a surface water-course, and thereby to external drainage 
on ancient lines. Thus the general features of the buried 
landscape are reproduced. 
But superimposed upon this persistent geography are the 
remains of that of red earth days ; that is to say, of a desert 
geography ; and just as water tends to accumulate between 
the hollows of the sand hills of the Jaffna peninsula, so, no 
doubt, it did among the dunes of red earth times. Thus, I 
think, are the villus, those curious ponds unfed by streams and 
provided with no outlets, of which I have spoken before, to be 
explained. Nearly two years ago Mr. H.F.Tomalin, the present 
Conservator of Forests, suggested to me that villus owe their 
origin to the action of the wind. Inowsee that his suggestion 
was probably much nearer the truth than I was at that time 
disposed to think. The fact that villus really are ancient 
features is rendered probable by the occurrence of stone tools 
on more recent sand dunes, which sometimes flank them on 
the north-east sides. The sand of these dunes is white; 
it was derived from the red earth and bleached by the hygro- 
phytic vegetation on the edges of the water before it was 
blown into its present position. The stone tools cannot have 
been blownup as well; and, as we haveseen, they are probably 

* See my remarks on this subject in “‘ Spolia Zeylanica,” Vol. X., 
Part 37, pp. 166-174. 
