HEEEHEEETUE. 



133 



beaches and broken shell fragments. Here and there on the lagoon side a 

 beach dam of small Areas and sand was thrown up, and a few hillocks of 

 dead Area shells cropped out upon the lagoon side of the flat. 



On the sea face of the atoll we could trace the corals down to twenty-two 

 fathoms. They are, however, all small masses of Millepores, Pocillipores, 

 Porites, and Madrepores, not to be compared in size with those growing in 

 the pools of the reef flat or in shallow water. 



On the reef flat the surface of the old ledge and the coral fragments were 

 all covered with patches of many-colored Nullipores, protecting the reef flat 

 from further denudation and disintegration. On the outer platform slope, at 

 the foot of the steep and high beaches, were thrown up masses of coral frag- 

 ments. On the outer sea face much of the dead material is not cast upon 

 the beaches, but is thrown back on the outer slope ; driven back and forth, it 

 is ground into fine sand and shingle supplying the material for the beaches. 

 The reef flats encroach extensively into the lagoon, forming extensive spits 

 indicated by the green color of the water. 



The reef flats of Hereheretue represent the condition of the flats of the 

 atolls of the Gloucester group. There is always more or less coral rubble 

 and shingle and little of the old ledge exposed, except where the outer part 

 of the flat is cleared of beach rock and shingle or boulders. Beach rock and 

 recent conglomerate take a 

 great development on the 

 inner parts of the reef flat 

 close to the base of the 

 beaches of the islands, where 

 it has been originally depos- 

 ited either upon the old ledge, 

 so as to conceal the greater 

 part of it, or between its out- 

 crops upon different parts of 

 the rim of the atoll either as 

 buttresses or walls or horses. 



The four atolls of Hereheretue, Anu-Anurunga, Anu-Anuraro, and Nu- 

 kutipipi are most interesting. Nukutipipi is the smallest atoll of its kind we 



Landing on Reef Platform, Hereheretue. 



