JALUIT. 287 



In many of the Marshall Islands coral boulders and dead corals have been 

 thrown up on the low and narrow land or over the reef flat before the 

 formation of islands and islets on the inner lagoon side had taken place. 

 They show the continuity in the formation of the outer land rim and of 

 the inner islands and islets forming spits, as at the eastern point of Arhno. 

 Many of the ditches or sinks we have noticed are formed by the junction of 

 these islands and islets in lines parallel to the outer land rim. The sinks 

 may be circular, elliptical, or long troughs. 



On our way to Imrodj Island (PI. 226, fig. 6), on the east face of Jaluit, 

 we came upon a mass of shells indicating either the extent to which the 

 lagoon has been filled up, or the extent to which patches of corals once 

 flourishing have gradually been overwhelmed by the sand blowing into the 

 lagoon. The island of Imrodj is on the east side of one of the northeastern 

 passes (PI. 162, fig. 2) ; it is flanked by a small sandy islet covered with 

 cocoanut trees ; the islet has been blown up on the reef flat during the 

 last seven years. Enormous breadfruit trees flourish on Imrodj and one 

 of the finest groves we have seen covers its central part. 



A section across the island of Imrodj is most characteristic ; on the 

 lagoon side a reef flat fully 500 feet in width slopes gently from the 

 outer edge to our anchorage into six fathoms. On the way from our 

 anchorage to the shore we passed through magnificent patches of Pocil- 

 lipores, masses of Porites and Madrepores growing most luxuriantly from 

 about four fathoms to the shore which is flanked by a comparatively 

 steep coral sand beach. From the summit of the sand beach, which is 

 perhaps five or six feet high, the slope extends inland, forming a sink 

 about one mile in length occupying the greater part of the island. The 

 lagoon sand beach is covered with fragments of corals and coral heads 

 from the adjoining reef flat, killed by exposure to the air and overgrown 

 by NuUipores. Similar boulder reef flats are found in many of the 

 Marshall Islands. 



As we go towards the sea face of the island at right angles to the lagoon 

 side, we come upon rolled masses of coral gradually increasing in size till 

 we reach the summit of the outer sea beach. There the coral rocks, the 

 coral and beach rock conglomerate boulders consist of huge masses thrown 



