CHAPTER VII. 
THE FORMATION OF THE MALDIVES AND LACCADIVES. 
In Chapter V. I indicated that our soundings showed that the main chain of the 
Maldive group lies on a relatively shallow plateau at a depth of about 200 fathoms. 
The chief problem that concerns us relates to the formation of this bank. There can be 
but little doubt that it is surrounded with precipitous walls or a steep slope for an 
additional 600 fathoms at least. Further there is indubitably a close connection between 
all the various banks of the Maldives and Laccadives, so that they would appear to have 
been built on the same set of foundations. Any explanation of the formation of one bank, 
then, must necessarily embrace those of all the others. 
The topography of the central deep plateau appears to me to almost preclude the 
idea that it was formed on the subsidence of a large central island. There is no trace 
of any such movement continuing to the present day, the only recent change being that 
which formed the land, a change which must have been one of elevation if it was not 
due to an alteration in the level of the sea. Under the subsidence theory the existing 
reef-banks around the central basin would have owed their origin to the direct upgrowth 
of the fringing and at a later time the barrier reef of this central island. The various 
reef-banks would according to this view have been formed on the breaking up of the 
original reef, and the channels between the banks would represent its passages. Where 
there are a series of the latter opening into the lagoon of an atoll or barrier reef, the 
majority of such channels have depths less than that of the central lagoon. Indeed it is 
extremely rare for any of them to equal in depth the lagoon, into which they give entrance. 
It might hence reasonably be expected that some trace of the original reef would be 
found in the channels between the larger banks in decreased depths, but this is not the 
case. The shallower water lies in the centre of the plateau and the depth gradually 
increases in the passages. Again the peculiarly open condition of the central basin between 
the banks is of importance in respect to this same question. Either the land must be 
supposed to have been of extremely uniform height so that there were no eminences in 
the centre, on which reefs would have built up, or it must be maintained that the present 
banks represent the positions of the peaks of the land, and that the original land, owing 
to too rapid subsidence, failed to acquire a continuous reef. Under the latter conditions it 
would be probable that the valleys separating the mountains along the two chains would 
be of less depth than the great central valley, a second position which is not supported 
in any way by the soundings. Indeed it is largely a question of suppositions, and in the 
case of the Maldives there are required a series so great and complex as to afford strong 
presumptive evidence against the view that the present reefs are in any way the continuations 
