226 J. D. Hague on the Guano Islands of the Pacific Ocean. 



Above the crown of the beach there is a sandj ridge which 

 encircles the guano deposit. This marginal ridge is about one 

 hundred feet wide on the lee side of the island, and is there com- 

 posed of fine sand and small fragments of corals and shells mixed 

 with considerable guano; on the eastern or windward side it is 

 much wider and formed of coarser fragments of corals and shells 

 which, in their arrangement, present the appearance of successive 

 beach formations. This margin is partially covered with a rank 

 growth of long, coarse grass, portulacca, mesembry anthem um, 

 and a few other species of plants. 



Encircled by this ridge lies the guano deposit occupying the 

 centre and the greater part of the island. The surface of this 

 deposit is nearly even, but the hard coral bottom which forms 

 its bed has a gradual slope from the borders towards the centre, 

 or, perhaps more properly, from northwest to southeast, giving 

 the guano a variable depth from six inches at the edges to sev- 

 eral feet at the deepest part. None of the grass that grows 

 abundantly on the margin is found on the guano, but there are 

 one or two species of portulacca occurring in certain parts, (par- 

 ticularly where the guano is shallowest and driest), and to this 

 is owing the presence of the fine roots and fibres in some of tue 

 guano. 



The entire deposit presents considerable uniformity in charac- 

 ter. Excepting some isolated spots of little extent there is n^ 

 outer crust, and the guano of the surface differs but little, if anj' 

 from that below. There is, however, some variety in the ap- 

 pearance of the guanos of the deep and shallow parts of the de- 

 posit. On the northern side it is from six to twelve inches deep : 

 is generally quite dry, and is a dark brown pulverulent substance 

 of rather coarse grain or texture, containing many thread;lhv;e 

 roots and fibres and whitish particles, among which Prof. Liebig 



of -water. From ttie shore to the edge of the guano deposit G, is from 300 to 4 

 feet. The perpendicular height from LL to the summit of the sand beach. &3- 

 twenty-two feet, and the depth of the excav.uioi> opposite this highest point is « 

 The dotted line, a^.^represents an old beach formation -which the cut expo5=ed- B 

 consists of large and small coral fragments and shells beneath which the f»"*^ ,"*^ 



The highest point of ab is fifteen feet above LL, which altitude, in accordance ^''t^ 

 ten feet in height, would, of itself, be an evidence of elevation and, conseque' ^ 

 a^ubTe uJnt « CT"* ^""^^^^ °*" *'^'^"^y-*''*>/f«t> '* ^"^^l'* ^e necessnry to ^| 



sterlyg 



the sandy ridge. 



probably violent westerly j 



tion My own observations favor the opinion that the seamade coral lauu ^ 



'.^rf Jf^-''';^*'')'^*'.*''^" *^" °^ ^^^1^^ f^«t- I>«"ng the prevalence of hg 



s^ffirLniT'"" '''^"*^ ^ ''^^^ ^°*^'^" «««» ^o ^ash up the l^ach with body and^ 



l^lrr r^^f^y *''^ P**^'^ ^^ ^P*" ^^ were lying on the crown of the \^ 



Mghteea feet above the level of the reef yiug ou i « 



