GEOLOGY AND TOPOCJ R A PI I V OF 1 1 A \VA II. 93 



discovered in 1822 l)y two \vlialin<i' vessels, Ixdli of wliicli were wrecked mi the 

 reef the same niiiht within ten miles of eacli otlier. thus giving the reef its 

 double name, and establishing a record for the locality tlinl lias served as a 

 danger warning to mariners even to the present day. 



Lisiansky, discovered in 1805 by a Ru.ssian. for whom i1 is iuiiikmI. is a 

 small oval island composed mostly of coral sand. It is alxuit two miles by 

 three miles in extent and is surrounded by shallow water, but is w ithcnit a central 

 lagoon. Like I\Iidway and Laysan, it has been visited by hied poachers from 

 time to time. In 1905 a party of Japanese were found on the island engaged 

 in killing birds for the millinery trade. It was estimated by the officers of the 

 U. S. Revenue Cutter Thetis, who arrested the otTenders, that they had killed three 

 hundred thousand birds during the season. 



Laysan. 



Laysan Island was an American discovery, made in 1828, and named by the 

 captain for his vessel. It was taken possession of by the Hawaiian Kingdom 

 and later proved to be a rich guano island. For years it was leased to a firm in 

 Honolulu, which removed thousands of tons of valuable fertilizer from it. 

 Laysan is about two miles long by a mile and a half in breadth. The wi'ilcr 

 has estimated that during the vear 1902 it was inhabited bv ten million sea birds 

 that roam over the central north Pacific Ocean. This island differs from those 

 previously considered in that it is unmistakably an elevated coral atoll, since 

 it holds in its center a large briney lake, that has its surface slightly above 

 the level of the sea that surrounds the island. The evidence seems to indicate 

 that what was a low atoll at some remote period, possibly during the late Pliocene, 

 was elevated and transformed, so that the atoll became a lake in mid-ocean 

 surrounded by a ring of coral sand. The island is in tui'n practicallx' sur- 

 rounded by a coral reef with here and there an opening of sufficient size to 

 admit a small row boat. 



The harbor is on the southwest side and aff'ords a safe anehorage in the lee 

 of the island. The island has been more or less continuously inhahited foi- a num- 

 ber of years, and has been visited on several occasions by natni'alists, so that its 

 fauna and flora have been more fully studied and the island made more widi'ly 

 known than any of the other islands in the leeward chain. In anothei- con- 

 nection the remarkable bird po])ulation for which Laysan is justly famous has 

 been referred to at some length. 



The guano deposits have been very extensively w(wkeil and ma\- now be 

 regarded as ])ractieally exhausted. The beds were located on the inner slopes 

 of the sand rim of the island at each end of the lake m- l.mtton. Oi-i^inally 

 they were from a few inches to two feet in thickness and \ai'ied lii-cally in ilie 

 percentage of phosphate of lime — the valualiic i)i-oi)ci-ty Uw which they were 

 worked. The bones and eggs of the birds whose excrement, in eomhination 

 with the eoral sand, formed the rich calcium plmsphate or guaim fertilizer, were 



