+ 
ORIGIN OF THE GROUP. 279 
By no other process could it have been formed. ‘This precipice is in 
the same line with a similar one forming the eastern coast of the island 
Niihau. The direction is transverse to the general trend of the 
group. 
The shore cliff or declivity, of two or three hundred feet, which 
prevails around the island on the south, east, and north, may have 
been formed by the sea before the coral reefs were sufficiently exten- 
sive to afford protection. 
The craters of the Koloa district appear as if they had been in 
action more recently than any other part of the island. 
With regard to the origin of the eastern shore ridge, there remains 
much doubt. It may be the result of a faulting and uplifting of the 
strata: yet this is not probable. ‘The shore plain, inside of it, is evidence 
that no extensive degradation has taken place over the surface of this 
plain since it was formed. It may be that we must look far back into 
the history of Kauai for its explanation, to a period before the mate- 
rial of the present mountains was ejected, when an earlier cone was 
broken down, and this ridge was left, as Somma now stands on the 
side of Vesuvius. In this case, the shore plain must have derived its 
lavas from the volcanic mountain which subsequently rose. 
VI. GENERAL REMARKS ON THE ORIGIN OF THE 
HAWAIIAN GROUP. 
A frequent effect of change of level in the earth’s surface, is a break- 
ing of the crust by the action of forces within. The linear arrange- 
ment of the volcanic islands of the Pacitic is thus explained ; and there 
is No more instructive example of it presented us, than is afforded by 
the Hawaiian Group.* ‘The Kea and the Loa ranges of mountain 
heights were pointed out in our introductory remarks. ‘The facts 
since brought forward show us that these several islands are not merely 
regions of general volcanic action proceeding from many vents of 
eruption, but that each is the simple result of one, two, or three cen- 
tres. As Hawai consists of three mountain domes, each a distinct 
* This fact, with regard to the Hawaiian Group, is recognised by von Buch in his 
work on the Canary Islands; and the general principle has long been admitted in the 
science of Geology. Some circumstances attending this rupturing, and certain charac- 
teristics not hitherto pointed out, come up in the following pages. 
