148 PERCY SLADEN TRUST EXPEDITION. 
perhaps, to suggest that here we have secured specimens, exposed by under-currents, of 
the mound on which Providence is situated, and that we have possibly obtained the 
first definite evidence of the nature of the foundation on which a regular and typical 
coral-reef has come into existence. 
On Oct. 4 we put nine dredgings down to 200 fathoms along the western side of. the 
reef up to Providence Island, off which we anchored for the night. Our hauls in 
200 fathoms were abortive, proving only the barrenness of the ground. Then on going 
into about 75 fathoms we secured a fine series of Aleyonaria with a few solitary corals 
and other sedentary animals. In addition, at 50 fathoms flat incrusting calcareous algee 
(Squamariaceze) were common. The colours of the Gorgonians were striking, as were 
also the perfect adaptations to them of the ophiurids, crinoids, and crabs that live on 
their branches. The slope had no “steep” such as one usually finds off coral-reefs, but 
fell very gently to 20 fathoms and then rather more steeply to over 300 fathoms. 
Foraminiferal sand was secured above 25 fathoms and coral-mud below 50 fathoms, both 
with masses of coral-rock. Finally, on the following day we ended up with a dredging 
off the north-west of the reef in 665 fathoms, securing two species of prawns, and a 
manganese-covered corner off a large mass of coral-rock, on which we were caught up 
for some time *. 
We next sailed to St. Pierre, which lies 17 miles to the west of the Providence 
reef, getting on the way a sounding of 1088 fathoms (fig. 39). From the sea St. Pierre 
presents an appearance remarkably like one of the Tongan or Fijian raised coral-islets. 
It is surrounded by perpendicular or overhanging cliffs, varying up to about 30 feet in 
height. A sandy spot to the north-west allowed us to land with Capt. Somerville. As 
we went ashore, we passed over a flat of about 40 yards in breadth, formed of bare — 
coral-rock and sand with patches of sponges and Aleyonarians. On landing we examined 
first the rock, and found it to be perfectly solidified and consolidated all over the island, — 
and to consist mainly of corals bound together by sand. The corals were of the regular 
reef species, with much Favia and Madrepora. A great part of the rock, especially near. 
the surface, is very crystalline, masses of clear crystals often radiating from the coral- 
branches. Much of the sand between was hardened into rock and reddened by guano 
and humus, some of it being very rich in phosphates, while the soil above consisted 
mostly of guano and vegetable mould +. 
A closer inspection confirmed the existence all round the island of cliffs, with caves 
driven in underneath for 10 to 25 yards. All the rock near the sea is pointed and pitted, 
showing that it has been weathered greatly. Its maximum height above the sea is 
about 40 feet, and this, added to the difference of tides (about 8 feet), gives 48 feet 
definite elevation. If to this we add loss by rain, erosion, &c., we cannot suppose the 
* Providence, like all the islands except Farquhar, Coetivy, and Cargados, is under the Seychelles Government. 
The island belongs to an Indian firm in Mahé and is under a half-caste manager. The coconuts are too closely — 
planted for the greatest profit. According to Horsburgh (loc, cit. p. 124), even a hundred years ago it was covered 
with coconuts and other trees. } 
+ St. Pierre has been taken in hand since our return to England and is now being regularly exploited for guano, 
of which it is supposed to have about a quarter of a million tons of payable quality. 
