16 j. stanley gardiner. 



2. Seychelle Section. 



This section comprises a semicii-cle of reefs and islands, extending from Reunion to 

 the Seychelles and then southwards to the Aniirantes and the Alphonse-Francois islands. 

 Rodriguez is an outlying basaltic island to the east of Mauritius, with a little raised coral- 

 rock; the reef is fringing or slightly barrier with low coral islets'. Agalegas and Tromelin 

 between the line and Madagascar seem to be of coral formation with fringing reefs; they 

 are probably slightly raised, though no definite evidence on this point is available. These 

 three islands may well all be separated from the rest by over 2000 /. of water, but the 

 main line so far as the soundings go would rather appear to be on a bank with at 

 most 1000 to 1500/ of water. 



Reunion to the south is a volcanic island, 10,069 feet high, with fringing reefs in 

 places, while Mauritius, also volcanic, 2700 feet high, has both barrier and fringing reefs, 

 which were visited by Darwin. Tracing the line to the north Cargados Carajos is a 

 crescent-shaped reef, awash, 30 miles long, in one place 4^ miles wide, with 7 low, coral 

 islands, which appear to be washing away; it has a shallow bank extending 16 miles off 

 to the west, but has in no way begun to assume an atoll form. The bank known as 

 Nazareth probably extends down with shallow water (under .50 /.) and includes the last- 

 named, giving a total length to the bank of 280 miles; the shallowest sounding is l-t /., 

 but the whole is ill-surveyed ; there does not appear to be any deeper central part. The 

 Saya de Malha, 150 miles further north, consists really of two considerable banks which 

 are probably not separated by more than a few hundred fathoms from the last, as compara- 

 tively shallow soundings extend out from each for a long distance. The northern bank, 

 75 miles long by 23 broad, has a ring-shaped reef, about 12 / deep (shoalest water 5 /) 

 with a central basin of 40 /., while the southern is 140 miles long by 120 broad, with 

 a rim to the N. and E. at 12 / but only a little shoaler (25 /.) to the S. and W., 

 and a central basin about 50 /. deep, a great bight in one place running in from the S. 

 with 60 to 70 /. The two banks are remarkable for the great breadth of their rims, 

 about 7 miles in the N. bank and 12 miles in the southern. A further small bank to 

 the S.E. has one sounding of 57 /. in the centre and rim 25 f. deep. 



The Seychelles lie about 200 miles N.W. of the last, with no bottom soundings in 

 the channel between. They consist of ten high granitic islands, mostly with fringing reefs, 

 on a bank 35/ deep, 200 miles long by 120 broad. The northern outliers, Bird and Dennis 



this section was obtained. Most of the .surveys of isolated as clearly to a time when the island stood at a higher level, 



islands in the regions comprised in this and the next section The present coral reef fringes the coast, extending about 



appear to have been made by Admiral Sir W. Wharton, F.E.S., 3 miles on the south-west side, but coming close inshore 



a most expert and careful observer. For information on on the east. An older reef, however, exists, now quite 



Madagascar consult " Madagascar, Mauritius and the other submerged in some places to a depth of over 90 fathoms. 



East-African Islands " by Prof. Dr C. Keller, 1901, who gives Upon it the present reef rests, and it extends westwards 



a full list of references. nearly 15 miles from the present coast, while to the east 



1 Vide " The Physical Features of Rodriguez," by it stretches about 6 miles. We have thus proofs of great 



Is. Bayley Balfour, Phil. Trnnti. It. S., vol. 168, pp. 289 — and intermittent oscillations of the level of the island." 



292, 1879. The raised coral-rock is described as forming I may be permitted to point out, that it is assumed that 



large, coralline, limestone plains of inconsiderable elevation. this submerged reef is of coral formation. Its contour 



Prof. Bayley Balfour proceeds: — "The existence of these corresponds, so far as it is known, neither with existent 



masses of coralline limestone indicates clearly a former friuging, nor barrier reefs. Its origin is probably rather to 



lower level of the island, and the evidence of raised beaches be traced to the former erosive action of the sea on a volcanic 



confirms this. But a consideration of the coral-reefs points coast. 



