370 On Coral Reefs and Islands. 
the sand-bluffs on the north side of Oahu. Since their forma- 
tion, this island has undergone an elevation of twenty-five or 
thirty feet; these hills, once on the shores, are now seventy 
feet above the level of the sea, and they face the water with a 
bluff front (due to degradation), in which the lamination is finely 
exposed to view. The structure is best seen in a transverse sec- 
tion, presented on the west side. The layers are but a fraction 
of an inch thick: at one of the hills large slate-like slabs may 
be obtained; they have a sanded surface, but are so hard within 
as to clink under the hammer. A particular description of these 
bluffs is given in the author’s remarks on the geology of the Ha- 
waiiay islands. 
rig 
fost i 
“De 
“8 se 
1 \\ Vm atts 
y EX ‘ pale New . 
KOC aa > EPS Cee AY 
SSAA ae GAN WX or i | ces ger ce 
i SHV , ag ON e Rains ; , = - : 
i Bs al Fee Pe wh . £\) \ \ AX\ \ WA 
TAM With eu ant sea US Ma fh N Wy ARS A Sas i 
See a es Eni a EEA ee 
Se ees a, Sa a Ss NN wR, 5 ee. 
: : 
ting ‘eae, ee = 
me yo ee 
Sie ce ak. Be ee UE OT 
qi" 1 “a, My f 
‘hh ash 
SE Np RS SS 
(PasihGe ait Vit sa me 
Se ae Ne * LS 
Sr alan wey Soe eS WN \\ ~ hc 
pa sw 
i. 
a 
\ 
Ny > 
— 
aaltenaies o MANN eng 
S e re, nice wer 
= " Sepenaneenteaad 
VME dt ee “ee fon ool | cae Nene 
_7 Ah al Se ec RE LD ea y Liti wahes'% 
, BLUFFS OF CORAL SAND-ROCK, NORTH SHORE OF OAHU. 
One of the most interesting facts, observed in connection with 
‘these drift jiills, is the absence of shells, and even of fragments 
of shells or corals, sufficiently large to be referred to either of 
these sources. The material is a fine sand, without org 
mains, although situated on shores off which, within - 
ie) 
ls and corals innumerable. 
* 
