118 SPOLIA ZEYLANICA. 
And Ceylon is not a land of exceptional precipitation. 
Look at Cherra Punji in Assam, with its yearly average of 
458 inches, ““and a maximum record of 905 inches said to 
have fallen during the year 1861, of which 503 inches came 
down in June and July.”* We who saw how choked the 
rivers were with sand after the rapid and disastrous floods 
of 1913 may well be glad that the rain stopped when it did, 
for otherwise the entire rice crop of the low-country would 
have been buried in a bed of mud and silt. i 
If the average yearly rainfall for Ceylon were as great as 
that of Cherra Punji, the low-country would be flooded out at 
least once a year. 
Let us see how Mr. Brooks’s contentions help us to interpret 
the plateau beds. 
Across the plain formed by the emergence of the ocean floor 
rivers would flow, probably much as they did in previous days 
when the land was more elevated, and when man first came 
to the Island. For these upheavals are generally very slow 
affairs, and the rivers would have time enough to cut anew 
their courses as the country rose again. But these, we will 
assume, were the days of the Great Ice Age, when prehistoric 
man was living in Europe under conditions of intense cold. 
Precipitation, as we have seen (by the thesis noticed above), 
was greater then than now, and so we see the rivers filling 
their valleys in the hills and pouring forth in great volume 
over the plains below. The renewed energy of the running 
water engendered by the heavy rains, and the rising country, 
would enable it to carry enormous loads as long as the gradient 
was steep enough to permit of a high velocity. But once the 
streams poured forth upon the flats, much of their power would 
be lost, their channels choked, and their detritus spread abroad. 
Large boulders would be dropped first, later the gravel, while 
some of the fine sediment would be carried out to sea or spread 
on distant portions of the plain. 


* Pascoe, E. H.: The Petroleum Occurrences of Assam and Bengal 
(Mem. Geol. Survey, India, Vol. XL., Part 2, Calcutta, 1914, p. 274). 
+ The transporting power of a current varies as the sixth power of 
its velocity ; so that if the velocity be doubled, the transporting power 
is multiplied sixty-four times (see I. C. Russel’s “ River Development,” 
London, 1909). 
