12 
MISSIONARY TOUR 
dently calcareous, and apparently a kind of sediment 
deposited by the sea, in which branches of white coral, 
bones of fish and animals, and several varieties of 
marine shells, are often found. A number of wells have 
been recently dug in different parts of the plain, in which, 
after penetrating through the calcareous rock, sometimes 
twelve or thirteen feet, good clear water has been always 
found ; the water in all these wells is perfectly free from 
any salt or brackish taste, though it invariably rises 
and falls with the tide, which would lead to the suppo¬ 
sition that it is connected with the waters of the adja¬ 
cent ocean, from which the wells are from 100 yards to 
three quarters of a mile distant. The rock is always 
hard and compact near the surface, but becomes soft and 
porous as the depth increases; and it is possible that 
the water in these wells may have percolated through 
the cells of the rock, and by this process of filtration 
have lost its saline qualities. The base of the moun¬ 
tains which bound the plain in the interior, appears to 
have formed the original line of coast on this side of the 
island, but probably in some remote period an eruption 
took place from two broad-based truncated mountains, 
called by foreigners Diamond Hill and Punchbowl Hill, 
evidently extinguished craters: the ashes and cinders 
then thrown out were wafted by the trade-winds in a 
westerly direction, filled up the sea, and formed the pre¬ 
sent extensive plain; the soil of its surface having been 
subsequently produced either by the decomposition of 
lava, or the mould and decayed vegetable matter washed 
down from the mountains during the rainy season of 
the year. 
Across this plain, immediately opposite the harbour 
of Honoruru, lies the valley of Amianu, leading to a 
