88 "ALBATEOSS" TEOPICAL PACIFIC EXPEDITION. 



On the northwestern face of Tahanea we find here and there a stretch 

 of a secondary lagoon similar to the one described on the south shore, but 

 not more than 20 to 25 feet in width. At the horn of the northwestern 

 point are fine patches of beach rock covering the old ledge, and coral 

 shingle, and black shingle thrown up on beach faces from six to seven 

 feet high (PI. 54, fig. 1). 



After passing the northeastern point, going southeast, we saw a 

 beautiful effect of the blending colors of the line of breakers, of the 

 dark masses of rocks and boulders, and of the sky line without any 

 special line of demarcation. We could see the flash of the columns of 

 white breakers, like the explosion of a torpedo, thrown high up in the air 

 against the gray sky, bringing out on the horizon a sharp line of dark 

 spots which were the boulders and rocks covering the reef flats. 

 Along this part of the atoll the reef flat is from 200 to 250 feet in width, 

 the lagoon edge being formed by an irregular belt of sand bars or of 

 beach rock shingle ; the central parts of the flat are covered with end- 

 less shingle bars at right angles to the trend of the sea face. 



The north face of Tahanea is low, narrow, with here and there a 

 broader island, say 800 to 1000 feet, running diagonally across the 

 narrow land rim of the north side, and connecting more or less, on 

 the lagoon side, the numerous ledges in the channel which separate 

 the outer reef flat from the wide inner reef flat, on which these broad 

 islands have been thrown up. 



Outcrops of the old ledge are not uncommon close to the narrow 

 outer reef flat of the north shore. 



Towards the northern point of Tahanea the atoll is edged with a some- 

 what narrow reef flat awash, not more than from fifty to one hundred feet 

 in width ; for six to seven miles the north shore land rim is low and narrow, 

 with only here and there an islet or ledge within the lagoon. On the face 

 on which are the entrances into the lagoon somewhat higher islands have 

 been formed, with rather more vegetation than is usual in the Paumotus ; 

 these islands are all faced by extensive coral sand beaches on the lagoon 

 side. More or less parallel with them on the interior of the lagoon are 

 scattered numerous sand bars and sand patches, many of them rising into 



