184 
THE GEOLOGISTc 
perties. In fact most of the facts in natural history can be explained 
by this theory ; but there are a few which at present cannot, such as 
the colours of certain larvsD, which are asexual. Even these may 
perhaps be the effects of the mysterious and unknown laws of corre- 
lation of growth and sympathy between different parts. 
We must remember that the theory of natural selection is subordi- 
nate to, and totally distinct from, that of the transmutation of species; 
and that if the former should be found wanting it would not effect the 
latter in the least degree. 
The third great argument urged against the theory of transmutation 
of species is the geological one ; and may be divided into two heads. 
1. The almost entire absence* of the remains of the numerous con- 
necting links that must have existedo 
2. The sudden appearance of groups of allied species, particularly 
in the lowest known fossiliferous formations. 
The answer to the first is that the geological record is extremely 
imperfect. There are reasons for thinking that most sedimentary- 
strata have been formed during subsidence. Besides the difficulty of 
accounting for the very thick ones in any other way, we must re- 
member that during subsidence a newly-formed deposit has the 
advantage of remaining quiet until it has had time either to harden 
or to be covered up. When land is rising, on the contrary, the loose 
deposits will be continually washed further and further away from it 
until a period of rest or subsidence gives them time to consolidate ; 
but while subsidence is going on the land and the inhabitable part of 
the sea will be decreasing, consequently there will be much extinction 
and little variation. When land is being elevated the contrary will 
obtain, therefore, most of the intermediate varieties will not be 
preserved. 
Most sandstones and clays have been accumulated near land ; for 
the finest mud or sand must sink before it can travel very far. Even 
in the exceptional case of the mouth of a great river, sediment 
has never been detected more than three hundred miles from the 
land. If rolled along the bottom by a current it would be stopped 
by the first valley it came across, which would act as a pm-ifier to the 
current in the same way that a lake does to a river. Limestones may 
certainly be formed at any depth ; but we have proofs in the organic 
remains of which they are generally full that most of them were 
deposited in not very deep water ; and although some, like chalk, may 
be forming in the middle of the ocean, yet I think that the pm^ity of 
deep water in most places, as proved by its blue colour,t is a sufficient 
guarantee that no deposition is going on ; and that this is true is 
* One reviewer has even said the " thorough and complete absence." See An. 
Nat. Hist, Feb. 1860, p. 140. 
* It is the purity, not the depth of the blue that proves the absence of 
sediment ; the depth of colour depends in a great measure on the quantity of salt 
it contains in solution. The North Atlantic between Ireland and Canada is not 
pure blue. 
