124 CORAL FORMATIONS. 
reason to believe that a distinct crater would seldom, if ever, be 
formed. 
b. The hypothesis, moreover, requires that the ocean’s bed should 
have been thickly planted with craters—seventy in a single archi- 
pelago,—and they should have been of nearly the same elevation ; for 
if more than twenty fathoms below the surface, corals could not grow 
upon them. But no records warrant the supposition that such a vol- 
canic area ever existed. ‘The volcanoes of the Andes differ from one 
to ten thousand feet in altitude, and scarcely two cones throughout 
the world are as nearly of the same height as here supposed. Mount 
Loa and Mount Kea, of Hawaii, present a remarkable instance of 
approximation, as they differ but two hundred feet: but the two sides 
of the crater of Mount Loa differ three hundred and fourteen feet in 
height. Mount Kea, though of volcanic character, has no large crater 
at top. Hualalai, the third mountain of Hawaii, is 4000 feet lower 
than Mount Loa. The volcanic summit of East Maui is 10,000 feet 
high, and is a fine example of a large crater; but the wall of the crater 
on one side is 700 feet lower than the highest point of the mountain ; 
and the bottom of the crater is 2000 feet below the rim of the crater. 
Similar facts are presented by all volcanic regions. 
c. It further requires that there should be craters at least fifty miles 
in diameter, and that twenty and thirty miles should be a common 
size. Facts give no support to such an assumption. 
d. It supposes that the high islands of the Pacific, in the vicinity 
of coral islands, abound in craters; while on the contrary there are 
none, as far as is known, in the Marquesas, Gambier, or Society 
Groups, the three which he nearest to the Paumotus. Even this 
supposition fails, therefore, of giving plausibility to the crater hypo- 
thesis. 
Thus at variance with facts, the theory has lost favour, and is no 
longer sustained even by those who were once its strongest advocates. 
The question still recurs with regard to the basement of coral islands, 
and the origin of their lagoon character. Shall we suppose, with some 
writers, that these islands were planted upon submarine banks, within 
one hundred and fifty feet of the surface of the sea? As has been 
said, there is no authority for the supposition. We nowhere find 
regions upon our continents with elevations so uniform in height; and 
submerged banks of this kind are of extremely rare occurrence. If 
such patches of submerged land existed, the lagoon structure would 
still be as inexplicable as ever; for the growing reefs of the Pacific 
