120 
THEORY OF THE FORMATION 
Ch. V. 
three loops, together sixty miles in length ; or like 
Eimsky Korsacoff, narrow, crooked, and fifty-four miles 
long ; or like the northern Maldiva atolls, made up of 
numerous ring-formed reefs, placed on the margin of 
a disk, — one of which disks is eighty-eight miles in 
length, and only from ten to twenty in breadth ? A 
further difficulty on this theory of the origin of atolls 
arises from the necessary assumption of so large a 
number of immense craters crowded together beneath 
the sea. But, as we shall presently see, a greater diffi- 
culty is involved, namely, that all these craters must 
lie within nearly the same level beneath the sea. 
Nevertheless, if the rim of a crater afforded a basis 
at the proper depth, I am far from denying that a 
reef like a perfectly characterized atoll might not be 
formed on it. Some such, perhaps, now exist ; but 
it is incredible that the greater number could have 
thus originated. 
An earlier and better theory was proposed by 
Chamisso : 1 he supposes that as the more massive kinds 
of corals prefer the surf, the outer portions of a reef will 
first reach the surface and consequently form a ring . 2 
I remarked in the third chapter that a reef, growing on 
a detached hank, would tend to assume an atoll-like 
structure ; if, therefore, corals were to grow up from a 
bank some fathoms submerged in a deep sea, having 
steep sides and a level surface, a reef not to be dis- 
1 Kotzebue’s First Voyage, vol. iii. p. 331. 
2 [By anticipation, some of the objections which have been raised 
of late years (see Appendix II.) are considered in this section.] 
