THE FORMATION OF THE MALDIVES AND LACCADIVES. 173 
of older barrier and perhaps fringing reefs. The original land would have to be regarded 
as a great plateau, which has sunk to or beyond its present depth. Even allowing that 
the average level of the whole plateau may have been considerably raised by any valleys 
having been filled in, it is surely remarkable that on a land site of 330 mules long by 
70 broad, an area of about 12000 square miles, no single peak should have continued to 
exist to the present time. The subsidence theory, further, is absolutely incapable of affording 
any adequate explanation of the presence within the limit of the Maldive and Laccadive 
groups of such large atolls as Suvadiva and Kolumadulu, small atolls as Addu and Minikoi, 
open banks as Tiladumati and Mahlos, isolated reefs as Fua-Mulaku and Toddu, and finally 
submerged dome-shaped or flat banks as found in the north of the Laccadives. 
The banks facing the central plateau drop almost precipitously to its level. It would 
seem hence that they were erected on it as their foundation, so that it will be necessary 
first to consider its formation. Two possibilities suggest themselves. The first is by direct 
upward growth on a deeper plateau, mound or series of mounds on the sea-floor, both by 
the agency of corals and sediment. This view I shall have occasion later on to discuss 
in some detail, but I must provisionally reject it here as affording in any way a sufficient 
explanation of the formation of such a great bank as our central plateau to a height of 
at deepest 200 fathoms from the surface. The second possibility lies in the cutting down 
of land above or below the sea by aerial, wave, current and tidal actions to such a depth, 
the detritus being supposed to have spread out and formed the plateau. First it is necessary 
to consider what evidence there is as to the depths to which currents extend and at which 
they, assisted by waves and tide, can move matter. There is very little doubt, but that 
currents may extend to considerable depths and sweep the ocean floor quite bare. Indeed 
wherever in the ocean a rocky bottom is found, its character is probably due to an ocean 
current. To quote Mr J. Y. Buchanan, “when the rocky bottom of the ocean comes up 
to moderate depths as in the oceanic shoals which I had the opportunity of examining in 
the ss. Dacia in 1883, these currents and the tidal element in them are very evident. 
In archipelagoes like the Canary Islands, which are separated by channels having often a 
minimum depth of 1200 fathoms and more, the crests of these ridges are swept bare of 
sediment, and are hard rock, generally calcareous and manganiferous!.” There is hence no 
inherent improbability im the original land or bank of the Maldives being cut down to a 
depth of 150 or even 200 fathoms. The position of the group too would be one eminently 
favourable to the action of the currents, the plateau rising abruptly and lying right in the 
middle of the Indian Ocean, fully exposed to the two monsoons. The tidal wave sweeps 
across the ocean along the lines of latitude, extending from the surface to the greatest 
depths. Meeting an obstruction, lying absolutely at right angles to its course and extending 
from the bottom at 2200 fathoms to within less than 200 fathoms of the surface, its 
energy would be dissipated in current which would be of such force that it alone would 
probably be quite sufficient to cause the washing down of the bank to its present depth. 
With such a current there certainly could not be in any case much deposition of sediment 
on so shoal a ridge. The general hard bottom found in our soundings can only be explained 
by the action of the currents, and on them lies, I consider, the solution of the question 
as to the formation of the foundations of the atolls and banks of the Maldives. 
1 «A Retrospect of Oceanography.” Report International opportunity of expressing my indebtedness to Mr Buchanan 
Geogr. Congress, London, 1895, p. 25. I may take this for discussing this matter with me. 
