CHAPTER IIL 
HAWAIIAN ISLANDS. 
Amon the groups of Polynesia, the Hawaiian exceeds all others in 
geological interest. The agency of both fire and water in the form- 
ation of rocks, is exemplified not only by results, but also by pro- 
cesses now in action; and the student of nature may watch the steps 
through the successive changes. He may descend to the boiling pit, 
and witness the operations in the vast laboratory, with the same deli- 
beration as he would examine the crucible in a chemist’s furnace. 
Thus the manner in which mountains are made, and islands built up, 
becomes a matter of observation. ‘The volcanic dome may be seen in 
the process of accumulation from overflowing lavas, and may be traced 
as lt increases in size. Again, disruptions of the accumulated rock 
may be observed, followed by their disappearance in the lavas below. 
While these volcanic mountains are still extending their limits, in 
one part of the group, in others, those changes are finely illustrated 
which they undergo through the action of water, gradual decomposi- 
tion, and other allied causes: and these effects are in every stage of 
progress :—in some instances, the slopes retain the even surface of 
the most recent lava stream ; in others, they are altered in every fea- 
ture, the heights worn down, the whole surface gorged out with 
valleys, and the depth of these furrowings of time indicate that the 
several islands differ widely in the length of the period since they 
were finished by the fires, and left to the action of the elements. 
Moreover, the coral formations of the shores present us with reefs 
now in progress from the growing zoophytes; and there are also reefs 
elevated many feet above the sea, having a close resemblance to 
beds of limestone. Besides these, there are hills of drift sand-rock of 
coral origin. ‘The various facts illustrate, therefore, all the results of 
coral growth and accumulation. 
