Sect. III. 
GREAT CHAGOS BANK. 
55 
distance, there was none with 210 fathoms. Small 
steep-sided banks or knolls, covered with luxuriantly- 
growing coral, rise from the interior expanse to the 
same level with the external rim, which, as we have seen, 
is formed only of dead rock. It is impossible to look at 
the plan (fig. 1, Plate II.), although reduced to so 
small a scale, without at once perceiving that the Great 
Chagos Bank is, in the words of Captain Moresby, 1 ‘no- 
thing more than a half-drowned atoll. 5 But of what 
great dimensions, and of how extraordinary an internal 
structure ! We shall hereafter have to consider both 
the cause of its submerged condition, a state common 
to other banks in the group, and the origin of the 
singular submarine terraces which bound the central 
expanse; these, I think it can be shown, have resulted 
from a cause analogous to that which has produced the 
bifurcating channel across Malilos Mahdoo. 
1 This officer has had the kindness to lend me an excellent MS. 
account of the Chagos Islands; from this papei, from the published 
charts, and from verbal information communicated to me by Captaiu 
Moresby, the above account of the Great Chagos Bank is taken. 
