200 MR. JTJKES-BROWNE AND PROF. HARRISON 



They may be called the " Oceanic Series," or, as Colonel Feilclen 

 has suggested, the " Thalassic Series " *. 



The Coral Limestone which forms so large a portion of the surface 

 of the island is only a crust or covering of very variable thickness, 

 and the true structure of the island is plainly visible to any one 

 who walks along the central heights, where the Coral Limestones 

 terminate in scarped cliffs and promontories, from beneath which 

 the Oceanic beds crop out and form in some places an undulating 

 plateau and in others a steep slope. The Scotland beds emerge at 

 a lower level (except where they are faulted up), and form the 

 rugged hills and valleys of the district from which they take their 

 name. 



The island is nearly surrounded by growing coral-reefs, which 

 are of special interest in connexion with the reefs that have been 

 raised above the sea-level. 



A general account of the geological structure of the island, of its 

 physical history, surface features, soils, and economic products, has 

 been printed in the "Explanation of the Geological Map of Barbados " 

 which we prei)arcd, and which has been published at the expense of 

 the Barbadian Legislature. In the following pages we propose to 

 give a more detailed account of the coral-rock of Barbados, with 

 some notice of similar rock in other West-Indian islands and of the 

 inferences that may be based on the existence of these raised reefs. 

 In a future paper we propose treating more fully of the Oceanic 

 deposits and of the conditions under which they were formed. 



The figure on the preceding page illustrates the general structure 

 of the island, being a section through Mount Hillaby, which is tho 

 highest summit, and across the widest part of the Scotland District. 

 Any other section across the island would show a larger surface- 

 area of coral-rock. 



§ 2. The Coral-reefs now growing. 



As raised coral-reefs cover so large a portion of the island, and 

 as the lower or most recent of the terraces must have been built up 

 under nearly the same conditions as those which now guide and 

 limit the form of the modern reefs, it is clear that any facts relating 

 to the latter will assist us in comprehending the features presented 

 by the former. 



Any facts relating to the form of the reefs now growing round 

 Barbados will have a further interest, because the island itself 

 afibrds proof of great and long-continued upheaval without the 

 slightest sign of subsequeiit subsidence. It is not of volcanic origin, 

 as so many coral-islands are, and has never been a focus of eruption, 

 consequently there is the less likelihood that its elevation was fol- 

 lowed by subsidence. There are therefore strong grounds for infer- 

 ring that the recent coral-growths round the island have been 

 formed in an area which was either stationary or was possibly for a 



* Col. Feilclen has given an accurate epitome of the geology of the island ir^ 

 a paper on the ' Birds of Baibados,' Ibis, Oct. 1889. 



