172 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



fuiTows ; the exposed surfaces of all the terraces are honeycombed and 

 .pitted and covered with small spires and pinnacles (PI. 103, fig. 3). At the 

 southwest point the face of the pitted and honeycombed cliffs shows four 

 deep cuts (PI. 106, fig. 3), the first trace of the inroads made by the sea in 

 their steep faces, which will eventually become small, narrow canons, sep- 

 arating wide buttresses similar to those shown on PI. 108. 



The lowest terrace forming a shelf round the base of the island at the 

 sea level has the appearance of an old beach rock bank (Pis. lOG, figs. 2, 3 ; 

 107, fig. 1). It is composed of a yellowish rock, very much decomposed. 

 The outer rim of the lowest terrace is remarkably high, and is built up by 

 Nullipores, which grow upon its face as far as the surf reaches (Pis. 106, 

 figs. 2, 3; 107, fig. 1). These masses of Nullipore are usually of a marked 

 yellow color. The lowest terrace is deeply undercut and full of blow- 

 holes ; its narrow platform is gouged out and then bridged over by corals 

 so as to leave passages through which the water is thrown up in spray by 

 nearly every swell (Pis. 106, fig. 3; 107, fig. 1). These blow-holes extend 

 nearly the whole length of the island. Where the two lowest terraces have 

 been undercut, the cliffs rise to a height varying from twenty to fifty feet 

 (Pis. 108, 109, 110). From the slope of the third terrace innumerable 

 little waterfalls drop from sixty to ninety feet vertically into the sea, 

 forming the deep ravines which are so characteristic of the west coast of 

 Nine. At one of the points which is deeply undercut, and cut back to the 

 third terrace, rise innumerable small pinnacles which cover the whole face 

 of the third terrace (PI. 106, fig. 3). Where this undercutting has been 

 going on extensively, small sand beaches are often formed at the base of the 

 ravines (Pis. 107, fig. 2 ; 108, 109), as, for instance, the beach at Avatele 

 immediately around the southwest point. A similar and smaller beach is 

 also found at the principal landing off Alofi, where we anchored (Pis. 107, 

 fig. 2 ; 108, 109). Between Avatele village and the point north of it, 

 are innumerable caverns and holes cut into the face of the second terrace 

 extending to the upper slope of the third terrace. The lowest terrace varies 

 in height from five to six feet. The second terrace varies in height from 

 thirty to fifty feet, and the slope of the base of the third terrace is about 

 fifty feet; the top of the third terrace appears to be from seventy-five to one 



