404 PERCY SLADEN TRUST EXPEDITION 



Inland from the cliffs for some distance sand is again the prominent feature ; it 

 has been blown up from the reef and further down the coast forms the high sand hills 

 called "Dunes Jean Louis" and "Dunes de Maistre": in the region of our section it 

 supports a somewhat stunted vegetation of coral-sand plants and forms a definite belt 

 200 — 300 yards wide, which may be called the " coast-zone." It is bounded by a rocky 

 ridge 20 feet above sea level, which appeared to be the highest point on the section : 

 thence inland a fresh type of country was met with, for the rock, instead of being of 

 the "champignon" type, is flat and smooth. It is formed of fragments of corals and 

 other organisms consolidated together. Under the influence of the weather it exhibits 

 large pavement-like slabs on the surface and is called " platin " in Creole. Pits and 

 shallow depressions are frequent, the pits being usually deep and containing tidally 

 fluctuating water ; as was noticed on the northern section they are all increasing in size 

 owing to erosion. The shallow depressions are not apparently homologous with the pits, 

 for the latter are natural spaces left in the rock during formation, while the former are 

 due to weathering ; they usually contain guano mixed with vegetable humus and support 

 a grove of trees. The vegetation of the " platin " country differs markedly from the 

 Pemphis scrub, for it is composed of a large number of trees and shrubs, which form small 

 groves separated by open bushy spaces ; near the sea the trees were all much stunted 

 by the prevalent winds, even the hardy Pemphis trees being dwarfed into a low thick 

 scrub resembling patches of gorse in consistency. As the section passed further inland 

 and the surface of the ground was lower, the vegetation became more luxuriant, the 

 depressions in the rock serving to retain a little rain-water collected during the wet 

 season. The rock remained of the same nature throughout almost the whole section with 

 the exception of two belts of " champignon," overgrown with Pemphis, about \ and f mile 

 from the sea. Near Takamaka are found the only permanent wells of fresh water on 

 the atoll : they consist of pits in the rock about 6 feet deep and 2 or 3 feet wide, with 

 a spring at the bottom ; apparently a rather impervious stratum of limestone in the 

 immediate neighbourhood has prevented the ingress of salt water and enough rain falls 

 in the wet season to preserve a steady though small flow in the dry. At Takamaka itself 

 is a grove of large banyan and "takamaka"* trees (40 feet)t, the latter not occurring 

 elsewhere on Aldabra. I suspect that the seeds were originally brought by the tortoise- 

 hunters, who regularly visited the wells for water, though it is just possible that they were 

 brought by birds, as the small pigeon, Alectroccenas aldabranus, eats them greedily. 



The section ended in the mangrove swamp at Abbot's creek, which does not differ 

 from any other creek found in the swamp into which it extends for about ^ mile. 



Other sections were cut from the lagoon to Point Hodoul, the most easterly part 

 of the atoll ; opposite Dunes Jean Louis ; in the west of Main Island ; on Picard Island ; 

 and at other places in the north of the atoll, but detailed description is unnecessary. 

 The whole of the north of the atoll, Polymnie, Malabar, the north of main island, supports 

 only Pemphis-bush. growing on " champignon " rock. The east of Main Island and south 

 as far as Dunes Jean Louis is of the "platin" type, interspersed with belts and patches 

 of Pemphis ; from Dunes Jean Louis to Dunes de Maistre there is a wide " shore zone," 



* CalophyUum Inophyllum. \ Where a number of feet is given in brackets, heights or elevations are intended. 



