PRELIMINARY- REPORT. 17 



caverns indicating the line of present action of the sea at the base of the 

 cliffs. As we steamed around the island there were distinct indications of 

 two additional terraces on the line of the vertical cliffs on the weather 

 side of the island. The position of these terraces was usually more clearly 

 seen along the face of the cliffs at prominent points, where they were 

 undercut much as I have figured them for certain cliffs in Vatu Leile, 

 Yangasa, Mango, Fulanga, and others in Fiji, in my report on the islands 

 and coral reefs of that group.^ 



Of course it is premature, from this examination of the w^estern ex- 

 tremity of the Paumotus, to base any general conclusions I'egarding the 

 mode of formation of those atolls ; certainly, as far as I have gone, there 

 is absolutely nothing to show that the atolls of the Paumotus have not 

 been formed in an area of elevation similar to that of Fiji. The evidence 

 in Rangiroa and in the atolls of the western Paumotus is very definite. 

 Makatea is an elevated mass of coralliferous limestone similar in all re- 

 spects to masses like Vatu Vara, Thithia, find others in Fiji. Like them, 

 Makatea is surrounded by a comparatively narrow shore platform cut out 

 from the base of the limestone cliffs, and on the seaward extension of 

 which corals grow abundantly to depths of seven to eight fathoms, when 

 they appear to become very much less numerous. So that it is not un- 

 natural to look upon the area of the Paumotus, as I am inclined to do, 

 as one of elevation, the raised and elevated land of which has been 

 affected much in the same way, by denudation and by erosion, as have 

 the masses of elevated coralliferous limestone of Fiji. Only there seems 

 to have been, from the evidence thus far presented, a far greater uniform- 

 ity in the height of the elevation of the Paumotus. This would render 

 the explanation I have given less evident had I not the experience of 

 the Fiji group to guide me. Evidence of this elevation is found at 

 the two extremities of the Paumotu Plateau, at Makatea, an elevated 

 island consisting of Tertiary coralliferous limestone, and at the Gambler 

 Islands, which are volcanic islands of considerable height (over 1300 feet). 

 Furthermore, as we shall see, there are other islands and atolls in the 

 Paumotu Group showing traces of this elevation, so that I am at any rate 



1 BuU. M. C. Z., Vol. XXXiri., 1899, Pis. 80, 84, 92, 100. 

 2 



