STONE AGES OF CEYLON. 105 
acts as a sorting agent, and separates lighter from heavier 
particles, so that in a wind-blown deposit we should expect to 
find an evenness of grain and an absence of pebbles. These 
two features are those of the red earth, but let us examine the 
matter more closely. 
I find that the vast majority of particles in the red earth are 
less than one-sixteenth and more than one-sixtieth of an inch 
in longest diameter. A similar statement can be made with 
regard to recent blown sands in the north of the Island. 
These figures are by no means bound to hold good for all blown 
sands for obvious reasons ; but I have selected this example 
from the north for comparative purposes. Now, since the 
wind is selective, we may well expect to find some sort of rule 
with regard to the proportion of the different sized particles 
which it will shift, or has shifted. There will always be a 
certain amount of very fine material present in a blown sand ; 
let us examine that. The average of eighteen specimens (all 
of which conform in the general size of their constituent 
particles with those of the red earth) collected over a seaboard 
of some 30 miles in length shows that 1:114 per cent. of the 
material is less than one-ninetieth of an inch in diameter, 
while an average of sixteen samples of red earth from different 
districts shows that 4°52 per cent. of its bulk is equally small. 
This is a very big difference, and this last figure is too low, for 
it only expresses the proportion of fine material (less than one- 
ninetieth of an inch in diameter), which is easily separated by 
means of a sieve. It says nothing of the quantity of snuff-like 
dust which clings to the larger particles. 
If the first figure then is of any use for comparative purposes, 
the red earth is either not a wind-blown deposit, or it is a very 
abnormal one. 
If you take a handful of dry red earth and sprinkle it in fair 
quantities before the breeze, you will find that the wind 
separates, more or less, the fine material from the coarse as it 
falls ; this argues badly for the zxolian origin of the red earth. 
But in this connection there is one significant point to be 
noticed. 
All the larger grains are composed of chemically stable 
materials, the vast majority being quartz. Now the ordinary 
