192 HAWAIIAN ISLANDS. 
previous ejections of the same eruption three more square miles, it 
gives 6,023,000,000 of cubic feet for the whole amount of lavas which 
reached the surface.* 
We have a still more accurate means of estimating the amount of 
lavas which passed from Kilauea, in the actual cubic contents of 
the emptied pit. The area of the lower pit, as determined by the 
surveys of the Expedition, is equal to 38,500,000 square feet. Multi- 
plying this by 400 feet, the depth of the pit after the eruption,t we 
have 15,400,000,000 cubic feet for the solid contents of the space 
occupied by lavas before the eruption, and therefore the actual amount 
of the material which flowed from Kilauea. ‘This is two and a half 
times the amount obtained from the estimated extent of the eruptions. 
The difference may be accounted for partly on the ground that fissures 
were filled as well as surfaces overflowed, and also that there may - 
have been eruptions beneath the sea not estimated. ‘This amount is 
equivalent to a triangular ridge eight hundred feet high, two miles 
long, and over a mile wide at base. 
The lava of the eruption is remarkable for the large proportion of 
chrysolite, amounting in some parts to nearly one-half, and occurring 
in coarse grains often a fourth of an inch thick. It is consequently 
very brittle, slabs being easily shattered to pieces by a tap of the 
hammer. ‘The sands of the seashore produced by the eruption consist 
largely of this mineral mixed with black grains of the comminuted 
lavas. In the abundance of chrysolite the lava is very unlike that 
formed in the crater either previous or subsequent to the eruption. 
The sand-hills are examples of elevations thrown up suddenly over 
fissures of eruption. ‘They consist of tufa of a rusty yellow colour, 
and are distinctly and finely laminated. ‘The sea is already encroach- 
ing on them, and has exposed the regular stratification of the interior, 
showing a steep inclination of the layers outward. Not a trace of 
tilting took place in the rocks beneath. ‘They are simple cones of erup- 
tion, formed of ejected cinders. ‘The sands are said to have been 
thrown out from the centre of each hill, while in progress; yet there 
is now no cavity at top. It appears that the action of the molten lavas 
* Allowing an average depth of but ten feet, the calculation would give for the whole 
amount 5,000,000,000 cubic feet. 
} As the measurements of the Expedition were made eight months after the eruption, 
we have allowed somewhat for the increase during that time, and also for cavities emptied 
beneath the ledge. 
