234 HAWAIIAN ISLANDS. 
on the northeast, the Eastern Range, and those of the southwest the 
Western Range. These mountains have an irregular serrated outline, 
and are intersected by deep valleys. ‘Two peaks in the former, ad- 
joining the valley of Nuuanu, called Konahuanwi and Waolani, are 
about 4000 feet high; and the peak Kaala in the latter, as ascertained 
by Dr. Gairdner, is 3850 feet in altitude. 
There are no mountain craters and no distinct cones among 
the summits of the range. Yet there is a general regularity of 
structure, which enables us to trace out the relations of these heights 
to those of more simple outline. The dividing plain, as we call the 
intermediate low land, slopes into both ranges of high land, and gra- 
dually declines on opposite sides to the sea. Its height, where 
greatest, is about six hundred feet. 
The mountain declivities, for the lower six to ten hundred feet, are 
mostly covered with a growth of grass; beyond this, they are enve- 
loped in forests. The shore plains on the southern or leeward side 
are dry, and the dusty soil of Honolulu is scarcely laid by a day’s rain. 
‘The shores of the island are deeply indented on the south side, 
where the dividing plain reaches the sea, and there is here a delta-like 
area of shallow waters or lagoons seven miles in breadth. ‘There is 
another bay of larger size, more open to the sea on the northeast side, 
called Kaneohe Bay. 
Through a large part of the circuit of the island, as shown on the 
map, there are extensive coral reefs, and to this feature, Oahu is in- 
debted for its principal harbour,—the one at Honolulu. The elevated 
reefs, the extent of which is shown by the yellow tint on the map, 
give increased interest to the geology of Oahu. 
The island is well watered, even on the leeward side, owing to 
the peculiar character of the mountains. The largest stream empties 
near Wailua on the northwest, after having cut a deep course through 
the dividing plain. It rises in the northwestern declivities of the 
astern Range, and in rainy seasons receives additions from the 
Waianae Mountains. ‘Till within half a mile of the coast it is but a 
rivulet; here it is enlarged from some subterranean springs and from 
the influx of the sea, and becomes a river sixty or seventy feet wide 
and six feet deep. From the same region, two or three streams flow 
southward into Pearl River lagoon. ‘There is another stream worthy 
of mention on the northeast side of the island in the Koolau district, 
which flows from the mountains over the plains of Kailua, passing 
through some pretty lakes; it has a width towards its mouth of eighty 
feet. 
