424 E. O. HOVEY WALLIBU AND RABAKA GORGES 





out from 50 to 250 meters, a narrow strip of beach had been restored, in- 

 creasing from nothing, or practically nothing, in May, 1902, to 40 or 50 

 meters in June, 1908. North of Larikai point the losses of the coast in 

 May, 1902, were insignificant, if any were suffered, and the gains in the 

 succeeding six years were correspondingly meager. 



Eabaka Eiver Valley 



The history of Eabaka river on the windward (east) side of Saint Vin- 

 cent presents an interesting variation from that of the Wallibu. The new 

 ash filled the old gorge completely near the point where it issued from the 

 hills, 9 with the result that a new gorge to the sea was cut, abandoning the 

 old channel about 3 kilometers from the shoreline. The new gorge was 

 speedily cut down nearly to grade level, and it discharged a large part of 

 the burden of ash in the upper catchment basin of the stream. The new 

 filling of the gorge, therefore, remains as a permanent change in the 

 topography below the point where the new gorge branches off from the 

 old. The Wallibu made a like change in its gorge after the eruptions of 

 1812, shifting its main channel from the north to the south side of the 

 Wallibu plantation. This change is indicated by the topography and the 

 chart, and note of it is preserved in the history or tradition of the island, 

 according to Doctor Anderson. 10 Another permanent change in the 

 drainage of the Eabaka was on the south side of the ash-filled gorge, 11 

 where ponded waters on the surface of the new ash finally, with the assist-* 

 ance of dams formed by secondary eruptions, cut a new gorge through 

 the old wall of the river and ultimately opened a way for the escape of 

 the drainage of a considerable portion of the old basin through that por- 

 tion of the old Eabaka Eiver channel, which extended from the foothills 

 to the sea. New material has been spread out over the preemption flood- 

 plain of the Eabaka in a mantle several meters thick. Where the Wind- 

 ward Side postroad crosses this plain, about 250 meters from the point of 

 the new delta, the mantle is shown, by a ravine which has not yet cut its 

 way down to grade, to be not less than 4 meters thick. Along this road 

 the old floodplain measures about 450 meters wide. North of this old 

 floodplain there is a narrow strip a few score meters wide of old coast 

 sand, bearing the seagrape, and then comes the new floodplain of the 

 Eabaka, formed since the eruption, which measures about 245 meters 



9 Hovey : Preliminary Report, p. 343, pi. xxix, fig. 1 . 



10 Philosophical Transactions of the Royal Society of London, series A, vol. 208, p. 

 279. 



11 Hovey : Comptes Rendus, IX Congres geologique international, 1904, p. 729. 



