114 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



Immediately to the westward of the entrance to Hao a ledge of beach 

 rock is exposed, overtopping a part of the old ledge reef flat. Both to the 

 west and to the east of the passage there are many shallow gaps, giving free 

 access to the sea to the interior of the lagoon. One, however, is very deep, 

 not more than 50 to 60 feet wide, across a narrow part of the land rim, 

 exposing the beach rock and the recent conglomerate covering the old ledge, 

 which here and there crops ont as small buttresses, about four feet in height, 

 at the base of the shingle beach, and runs out on the broad reef platform of 

 the western face. On the north side the sea face of the land rim is com- 

 posed of alternating reaches of coral sand and buttresses of old ledge. 



The northwest horn of Hao (PI. 67, fig. 3) is formed by two islands, one 

 on the north face, the other on the western, separated by a wide flat nearly 

 planed down to the level of tlie sea, and out through but still connecting the 

 two sides of the horn, and covered over with a mass of beach rock and old 

 ledge boulders, with here and there a sand bar. 



Beyond the northwest point we came upon many cuts forming short 

 headlands flanked by shingle beaches and lines of beach rock or coral 

 boulders. The reef flat and the land rim (PI. 67, figs. 1, 2, 4) vary greatly 

 in aspect as we steam along the west face. In the interior of the lagoon 

 as seen from the west side we could distinguish a great many shoals and 

 ledges looming up in all directions (PI. 67). 



At one point of the western face the islands run at a sharp angle across 

 the wide reef flat, with water gaps of considerable depth between them. 

 The sea end of the islands was tipped with beach rock boulders or coral 

 shingle, while along the sides of the islands, on the lagoon side, extended 

 fine coral sand. 



At anotlier point the islands were replaced by bars of coral shingle run- 

 ning diagonally across the reef flat, separated by shallow gaps and abutting 

 on the lagoon side on small sand islets and sand bars. Nowhere perhaps 

 have we seen better examples of the transition between a small high bare 

 sand bar, or one a little larger witli one or two stunted bushes, passing into 

 a still larger one with a thriving belt of bushes, next a somewhat larger 

 one with a few cocoanut palms, and finally a large island such as are char- 

 acteristic of the atoll rim with its full quota of coral reef vegetation (PI. 67). 



I 



