248 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



that oif any other group of coral islands we have examined.' The beaches 

 of the islands on the south face of Tarawa consist of fine coral sand ; the 

 islands themselves are extremely narrow ; they are covered with cocoanut 

 trees and shrubs. The sand beaches have been formed as low dunes ; they 

 are somewhat higher than the islands and islets immediately to the north. 

 Beach rock and conglomerate ledges characterize the southern face of many 

 of these islands ; none rise more than a foot or two above high-water mark. 

 We observed, coming through one of the gaps opposite our anchorage, a 

 mass of discolored water, which spread fan-shape a considerable distance out 

 to sea. This material is derived from the immense shallow reef flats to the 

 rear of the gap on the southern face of Tarawa. Similar streams pouring 

 out the muddy water from the shallow bay to the rear of the Florida Keys 

 are seen at Caesar's Creek.^ 



At the gap opposite our anchorage, are a number of islands, more 

 or less parallel to the coast line, forming a secondary lagoon, similar to 

 those of the southern coast of Tapeteuea (Pis. 140, fig. 4 ; 141, figs. 2-4). 

 The eastern part of the southern face of Tarawa is flanked by a land 

 rim ; its western half is flanked by islets ; the western horn is formed by 

 a wide triangular reef flat, gradually increasing in width to about 1000 

 feet at low tide. 



To the eastward of the gap where we anchored, or rather of the long spit 

 which forms the western side of the gap, a series of islets extends at right 

 angles to the line of breakers, separated by shallow flats, which connect the 

 inner lagoon with the sea (PL 141, figs. 2-4). The lagoon extremities of 

 some of the islands are connected, thus forming deep bays extending north- 

 ward from the sea face, and communicating through shallow passages with 

 one another on the lagoon face (PL 141, figs. 2-4). Immediately across the 

 lagoon extremities of these islands, a low sand bar extends, flanked with 

 beach rock conglomerate, more or less elevated ; this forms the beginning 

 of a secondary lagoon extending behind the spit of the western side of 

 the gap, and shows, perhaps, better than elsewhere the mechanical causes 



1 Prel. Report "Albatross" Tropical Pacific Expedition, Mem. Mus. Comp. Zool., 1902, XXVL, 

 No. 1, p. 61, Stations 200, 201. 



" Bull. M. C. Z., XXVIII., No. 2, 1896, p. 46, PI. XIV. 



