TIKEi. 71 



At one point we saw a great accumulation of large old ledge rocks with a 

 regular pavement of smaller boulders piled up on the reef flat in front of 

 them ; this line of old ledge boulders extended fully one and a half to two 

 miles. These large boulders are evidently a part of the old ledge still 

 in place which crops out on the sea face of the island. 



The island at the north end of the atoll shows the same features char- 

 acteristic of the islands we had seen thus far near Pakaka Pass, and others 

 on the weather rim ; being somewhat more exposed to the action of the sea, 

 the shingle beach is fully from eight to ten feet in height ; occasionally a 

 large head of old ledge crops out at the foot of the beach, and its remnants 

 are the scattered boulders occurring on the flats, extending towards the 

 lagoon beach of tlie land rim. A second islet not more than twelve inches 

 high is made up of beach rock consisting of fragments of recent corals and 

 of fragments of the old ledge, as well as boulders of the same material ; it 

 extends to the edge of the flat sloping into the deeper part of the lagoon. 



Tihere Entrance is a short pass through a narrow part of the reef flat, pre- 

 senting no special feature. 



Tikei. 



Plates 40, figs. 2^4 ; 4.1-U, ^01, 203. 



Tikei was discovered by Kotzebue in 1815. It is circular, about ten 

 miles in circumference, and is an elevated coralliferous limestone island. 

 The central part of the island is occupied by an indistinct sink, which rep- 

 resents a stage of denudation and of erosion somewhat more advanced 

 than that of Niau (PI. 44). The island is so well covered with vegetation 

 and with decomposed coralliferous limestone material (PI. 4o) that it is diffi- 

 cult to trace the outcrops of the old ledge. These, however, we came upon 

 in the small outlier rising from the pool (PI. 44) which occupied the lowest 

 part of the shallow sink of Tikei. There is no lagoon proper, and the denu- 

 dation of the old ledge has taken place to such an extent that the sea finds 

 access to this shallow sink, which differs from that of Niau only in depth and 

 in the height of the bank, which in the case of Niau prevents inroads of the 

 sea, while at Tikei it has access to the central sink through the shallow 



