AGASSIZ: FIJI ISLANDS AND CORAL IlEEFS. 135 



which however he considers as belonging to the present epoch. Elevated 

 coralliferous limestones also exist in the New Hebrides as well as on the 

 southei'n shore of New Guinea. 



The time of this Fijian elevation we cannot at present ascertain. It is 

 not unnatural to assume that it was coincident with the elevation of 

 Northern Queensland, and that the area of elevation included New 

 Guinea, the islands to the east of it as far south as New Caledonia, and 

 as far east as the most distant of the Paumotus (Gambler Islands), 

 and extended northward of that line to include the Gilbert, Ellicc, 

 Marshall, and Caroline Islands ; and that since this epoch of elevation 

 the islands within that area have been, like Northern Australia, subject 

 to an extensive denudation and erosion, many of them being reduced to 

 mere flats but a few feet above the surface of the sea, others worn away 

 to represent to-day but a small portion of their former extent. It is 

 upon the reef flats thus eroded, or around the islands and islets which 

 are the remnants of a former period, that the corals of to-day have ob- 

 tained a foothold. And further, by the mechanical action of the sea 

 combined with that of the trade winds, channels have been excavated out 

 of the substratum underlying the coral reefs to form the lagoons of the 

 barrier i-eefs and atolls of Fiji. 



So that, as far as we can judge from the case of the Fiji Islands, the 

 shape of the atolls and of the barrier reefs is due to causes which have 

 acted during a period preceding our own. The islands of the whole 

 group have been elevated, and since their elevation have, like the 

 northern part of Queensland, remained nearly stationary, and exposed 

 to a great and prolonged process of denudation and of aerial and sub- 

 marine ei'osion, which has reduced them to their present height. The 

 submarine platforms upon which the barrier reefs have grown being 

 merely the flats left by the denudation and erosion of the central island, 

 while the atolls are similar flats from the surface of which the islands 

 have at first disappeared and the interior parts of which have next been 

 removed by the incessant scouring of the action of the sea, the ceaseless 

 rollers pouring a huge mass of water into the lagoon, which finds its 

 way out of the passages leading into it or over the low outer edges of 

 the lagoon. These atolls and islands, suiTounded in part or wholly by 

 encircling and barrier reefs, have not been built (as is claimed by Dana 

 and Darwin) by the subsidence of the islands they enclose. They are 

 not situated in an area of subsidence, but on the contrary in an area of 

 elevation. The theory of Darwin and Dana is therefore not applicable 

 to the Fiji Islands. 



