276 HAWAIIAN ISLANDS. 
plates, and many of the lamine are but an eighth of an inch thick: 
though firmly cemented, they still hardly bear handling. ‘They fre- 
quently alternate with thicker layers of loose and coarser sand, giving 
a distinctly stratified appearance to the sections. Some of the 
cemented layers were four or five inches thick, but they were not of 
equal firmness throughout. 
The plain formed by these accumulations is from four to ten feet 
above the sea, which is not higher than the sands are thrown upon 
the present beach of the bay, where the formation is still in progress. 
We have no data for determining the rate of increase. This rate must 
be less now than formerly, as the shores are longer and rise from 
deeper water, and the reef is comparatively of less extent. 
These deposits contain, in some parts, the shells and corals of the 
present shores but little altered, and resembling beachworn speci- 
mens. There is a small bank of this kind near the mouth of the river, 
four or five feet above the existing level of the sea. But such beds of 
shells are not common, and by far the greater part is without a frag- 
ment larger than a grain of sand. It occasioned some surprise, also, 
that these sand deposits, formed at the mouth of a river fifty yards 
wide, should be nearly pure from mountain detritus. ‘The hills, two 
to three miles back, are covered with loose soil, and the banks of the 
streain, beyond the termination of the coral sand deposit, consist of soft 
earth from the adjoining declivities: yet it is rare to find a basaltic 
pebble in the layers, and there is but a trace of earthy material. A 
few scattered points, of a brown colour, and some of chrysolite, may 
be detected. Facts of this kind have been noticed on a former page, and 
they show how uncertain the evidence which a particular deposit may 
present with regard to the nature of the surface of the country adjoin- 
ing, or the amount of life in the waters. The fact stated is actually 
no more remarkable than the freedom of the present beach from 
basaltic material, for all these accumulations have had a beach origin. 
The detritus of the rivers is mostly carried off to sea; and that 
thrown up on the beach, is so light as either to be washed away 
again, or is driven far back of the beach by the winds. The plain is 
covered with eight to thirty inches of black earth, arising in part, per- 
haps, from this source, and from the dust which the currents of air 
bring in from the high country around. In the shores of the river, 
for a mile from the mouth, there were ten or twelve inches of black 
earth, six or eight inches of brownish earth containing an occasional 
shell, and, below this, several feet of grayish-white coral sand or sand- 
