606 THE POPULAR SCIENCE MONTHLY 
atoll is built upon a submarine volcanic mountain upheaved from the 
ocean’s floor; but in either case the relation between coral reefs and 
voleanic peaks is one that possesses a real importance for the zo- 
ologist. 
The two voleanoes of Savaii and Kilauea occur in island groups that 
are in every way typical of the so-called “high” islands of the Pacific 
Ocean. The Samoan Islands, including Savaii, lie almost on a 
straight line running nearly east and west. Upon examination they 
prove to be of various ages, for the westernmost, Savaii, bears the active 
volcano and displays other indications that it is more recent in origin 
than its neighbor, Upolu; this island, in its turn, is younger than 
the more rugged Tutuila and Manua to the east. The Hawaiian Is- 
lands, containing Kilauea, also range with some regularity along a line, 
which in this case runs west-northwest and east-southeast; but one 
very interesting difference consists in the fact that the newest island, 
Hawaii, lies at the eastern end of the group, while the relative geolog- 
ical ages of the other islands correspond with their serial geographical 
order westward to Kauai, the oldest and most sharply sculptured mem- 
ber of the group. In all other essential respects, the Samoan and 
Hawauan Islands are closely similar. Our interest centers about the 
peculiar features of their two active volcanoes, and the ways in which 
these agree and differ. 
The new volcano on the island of Savaii is assuredly the more im- 
pressive of the two. Its total mass is great, but this feature is not 80 
striking as its remarkably rapid development in the short period of 
five years; this development and the continual flow of fiery lava from its 
vast crater entitle it to supreme place in the array of volcanoes now in 
activity. It les about eleven miles back from the coast nearly opposite 
the middle of the north shore of Savaii, which is roughly rhomboidal 
in outline and forty miles long. Approaching this part of the island 
by day, the most striking features of the panorama are the two vast 
clouds of steam that rise from the places where molten lava pours in 
cascades into the ocean (Fig. 1). Upon the glistening black slopes 
beyond, jets of vapor mark the vents in the roofs of the tunnels through 
which the fluid lava runs upon its seaward journey from the crater; 
and from the crater itself, two thousand feet above sea level, rises a 
similar fountain of thin steam that quickly merges with the dense 
clouds above. 
When one looks upon the enormous mass of this new mountain, it 
seems impossible that five years could be sufficient for its formation, yet 
this is actually the case. The first crater appeared in August, 1905, 
upon the floor of a beautiful green valley. As cinders and lava were 
cast forth, they gradually built up a larger dome and spread out to form 
the first strata of the great volcanic field. The flow followed the valley 
