236 "ALBATROSS" TEOPICAL PACIFIC EXPEDITION. 



Arorai. 



Plate 223. 



Arorai Island, the aonthernmost of the Gilbert Islands, is about six miles 

 long, and half a mile wide, running from southeast to northwest ; it is a low 

 island with a high beach and a small brackish lagoon in the southern part 

 of the island. On the southwest side the island is flanked by a steep 

 shingle beach, at the base of which cropped out, here and there, short 

 stretches of conglomerate beach rock. The high and steep white shingle 

 beach shows that the southwestern part of the island must, comparatively 

 lately, have changed its character, as the northern part of the beach is 

 covered with I'ough, highly weathered and pitted black coral rock shingle. 

 The northwesterly winds, during the change of the trades, blow with con- 

 siderable force, and this may account for the changes that have occurred in 

 the outline of the western part of the island. At the western spit is a 

 huge pile of stones, evidently built by the natives in former times, of the 

 origin of which the natives of the present day know nothing ; so that it is 

 probable that the topographical changes of the western side of Arorai have 

 been comparatively slight, and limited, perhaps, merely to the migration 

 of the shingle on the high beach southward or northward, according to the 

 direction of the prevailing wind. Off the central part of the island, the 

 reef flat is wider than at the two extremities, and parts of it are covered 

 with flat slabs of beach rock. 



Onoatoa, 



Plate 223. 



Onoatoa, the next atoll of the group we visited, is about twelve miles 

 long ; its lagoon is five miles at its greatest width. We examined the 

 southern part of the atoll, and steamed along a part of the land rim of the 

 eastern face; this forms a large crescent open to the west. The gaps 

 between the islands and islets are so shallow that at low water the 

 narrow land rim of the eastern face of the atoll is continuous. The west 

 side of the lagoon is open, and only protected in the central part by 



