260 HAWAIIAN ISLANDS. 
The eruptions of the eastern mountain continued long subsequent 
to the extinction of the western vent. The two mountains, as the 
extent of valley-degradation and other facts show, had nearly the 
relation in age of the two which constituted Maui, or the two, Loaand 
Kea, of Hawaii. The lavas of the former, as now with those of Mount 
Loa, flowed over the foot of the other cone, and raised the intervening 
plain by accumulations of layers of compact rock and tufa or conglo- 
merate. ‘The features of the eastern slopes of the Waianae ridge 
exhibit distinctly this half-buried character. 
Subsequent to the convulsion that rent the island of Oahu, the 
eruptions of Kaneohe Bay, now not far from the centre of former 
action, must have taken place, and they may have been one of the 
immediate effects. ‘The scoria and cinders about the Pali, at the 
head of Nuuanu Valley, were also ejected after this event. Nuuanu 
Valley itself may have been the course of an earlier outbreak, like that 
which we have alluded to on Hale-a-kala. The several tufa cones 
and the lava eruptions associated, occur over fissures. Respecting 
their age we can arrive at no very definite conclusions, though we 
may infer with probability, that they were the last extinguished fires. 
That corals had already begun to grow, is apparent both from the 
fragments of coral imbedded in the tufa, and the incrustations of lime. 
The nature of the eruptions producing these tufa cones is evident 
from their position and structure. Previous to the rise of twenty-five 
or thirty feet, which the island has experienced since its fires became 
extinct, their bases were below the level of the sea. The cones of 
Koko Head, which constitute a peninsula, even now rise from the 
water’s edge, and must have commenced beneath the sea; and Dia- 
mond Hill and Kaneohe Point are other regions made into dry land by 
the eruptions, and enlarged by the subsequent elevation of the island. 
The finely laminated character of the tufas, so much like some 
alluvial deposits, would, alone, prove the same fact as regards their 
semi-submarine, or, at least, maritime origin; for large quantities of 
water and steam must have ascended and descended with the showers 
of the conical mountain into the sea.—p. 185. Humboldt mentions, (see Researches, i, 
238 ; also Cosmos,) that the volcano of the Andes, Capac-Urca, was once more lofty than 
Chimborazo ; but suddenly fell in. Carguairazo, eighteen thousand feet in height, crum- 
bled together on the night of the 19th of July, 1698, leaving only two enormous rocky 
horns of the crater. On 'Timoa, one of the Moluccas, in 1638, a mountain entirely dis- 
appeared, and a lake took its place ; previous to the catastrophe it had served as a prodi- 
gious watch-light, and was seen at a distance of more than three hundred miles. See 
farther, Scrope on Volcanoes, p. 163. 
