180 DISTRIBUTION OF CORAL-REEFS. Ch. VI. 



pression ' madreporitic rock;' but at the same time it is, I 

 think, scarcely possible to look at the chart of the linear islets 

 running in front of the coast from the equator far southward, 

 and rising to a greater height than can be accounted for by 

 the growth of coral, without feeling convinced that a line of fring- 

 ing-reefs has been elevated at a period so recent, that no great 

 changes have since taken place on the surface of this part of 

 the globe. Some, also, of the higher islands of madreporitic 

 rock on this coast, for instance Pemba, are singularly shaped, 

 apparently showing the combined effect of the growth of coral 

 on submerged banks, together with their subsequent upheaval. 

 Dr. Allan informs me that he never observed any elevated 

 organic remains on the Seychelles, which come under our 

 fringed class. 



The nature of the formations round the shores of the Red 

 Sea, as described by several authors, proves that the whole of 

 this large area has been elevated within a very recent tertiary 

 epoch. A part of this space in the appended map is coloured 

 blue, indicating the presence of barrier-reefs ; on which cir- 

 cumstance I shall presently make some remarks. Eiippell 1 

 states that the tertiary formation, of which he has examined 

 the organic remains, forms a fringe along the shores with a 

 uniform height of from 30 to 40 feet, from the mouth of the 

 Gulf of Suez to about lat. 26°; .but that south of 26°, the 

 beds attain only the height of from 12 to 15 feet. This, how- 

 ever, can hardly be quite accurate ; although possibly there 

 may be a decrease in the elevation of the shores in the middle 

 parts of the Eed Sea, for Dr. Malcolmson informs me that he 

 collected shells and corals, apparently recent, from the cliffs 

 of Camaran Island (lat. 15° 30' S.) at a height of between 30 

 to 40 feet ; and Mr. Salt (Travels in Abyssinia) describes a 

 similar formation a little southward on the opposite shore at 

 Amphila. Moreover, near the mouth of the Gulf of Suez, 

 although on the coast opposite to that on which Dr. Eiippell 



1 Eiippell, Eeise in Abyssinien, Band i. s. 141. 



