BY W. G. WOOLNOUGII. 445 



eastern end of Korobasabasaga at a place called Mataicicia. It 

 thus drains part of the area to the south-west of the Wainivalau 

 Valley, and proves a southward and westward extension of the 

 crystalline rocks met with in situ in the latter stream. Judging 

 from the size and abrasion of the boulders, I judge that the 

 granitic rocks occur in situ some ten or fifteen miles (by river) 

 north of Delai Lasakau on the Waidina. 



There is little to add with regard to the upper portion of the 

 Waidina Valley with the exception of some rather striking topo- 

 graphic details. There is a decided suggestion in places of 

 block-mountain formation; the crests of the blocks have a uniform 

 gentle slope of about 10° in a southerly direction. Fairly con- 

 siderable streams continue to within a mile or thereabouts of the 

 water-parting between the Waidina and Wainikoroiluva.* They 

 then bend north and south, and so flow paiallel to the divide. 

 The latter is itself parallel to the line of weakness manifested in 

 the Medrausucu Range, and, like it, is a linear range of andesitic 

 agglomerates. The most striking feature is, however, the nature 

 of the pass. This has a level floor, about two miles wide, bounded 

 north and south by the towering clifl-faces of Nairibiribi and 

 Natabuwaitui. These answer in every respect to the cliffs 

 bounding the gorges in the Medrausucu Range, through which 

 issue the main streams flowing eastward. The resemblance is 

 so striking that there can be little doubt, I think, that these 

 cliffs mark a comparatively recent water-gap, and indicate a very 

 profound disturbance of the drainage-systems of this part of the 

 island in late geological time. 



An examination of the map (Plate xii.) will show that the 

 trend of the Main Navua Valley is markedly collinear with that 

 of the Waidina River. Not only is it collinear, but it is very 

 nearly concurrent. The only break in continuity is at the gap 

 described above, and the water-parting here is not more than 

 about two or three miles wide. The last of the Waidina water 

 crossed on the track is 180 feet below the summit of the pass, 



* Called in error the Navua River in my former paper. 



