OAHU. 261 
of cinders. The tufa hills of the eruption in 1840, at Nanawale, are 
an exact representation of these cones in most respects, though of less 
extent, and of more rapid formation. The occurrence of the coral and 
interlaminations or incrustations of lime correspond well with these 
facts. About the Salt Lake region, there were evidently numerous 
pools of boiling water in operation, forming, perhaps, a scene of geyser 
eruptions during some part of their action. It will be remembered 
that there are several coalescent basins, with circular bays on the east 
and west sides, appearing as if there had been a great number of 
active centres; and from the size of some, the hot waters of a single 
area may have been a mile or more in circuit. ‘The lower flat basins 
are now at low-tide level, and the coral ledge pointed out, is proof of 
their former submergence. A farther study of the Alia-paakai region, 
may give sufficient evidence for believing that the salt of the lake, in- 
stead of being derived through the tides from the sea, arises from salt 
in the earth or tufa below, boiled down by these fires. The existence 
of salt plants on the upper salt basin, now forty feet above the sea, 
would be thus explained. Other facts, with regard to the fountain 
of waters playing most copiously in wet weather, and not appreciably 
in dry weather, all harmonize with this mode of explanation. 
In pointing out the characters of the two lofty cones of Oahu which 
originated the islands, tracing their history to their rupture and _par- 
tial subversion, and indicating other subordinate eruptions and boiling 
springs upon the coast, Geology looks far back into the earth’s past 
history. The facts are not, however, hypothetical, but worthy of full 
confidence. The language in which the events are recorded, is not of 
doubtful character ; for it is the same in which the operations of pass- 
ing events are journalized on the earth’s surface. ‘The interpretation 
is but a necessary conclusion based on the principle that “ke produces 
luke. We have called in no new powers, nor taxed known powers 
beyond their limits. The forces that have buried mountains, or raised 
their heads to the clouds, are not of speculative origin; for the lofty 
summits and the submerged lands bear their own evidence to the 
changes which the surface of the earth has undergone. And to these 
effects, the merest tyro in geological science can bring forward abun- 
dant testimony. 
66 
