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It will be much more convenient to discuss this question in the chapter on the Imperfection of the geological record; and I will here only state that I believe the answer mainly lies in the record being incomparably less perfect than is generally supposed; the imperfection of the record being chiefly due to organic beings not inhabiting profound depths of the sea, and to their remains being embedded and preserved to a future age only in masses of sediment sufficiently thick and extensive to withstand an enormous amount of future degradation; and such fossiliferous masses can be accumulated only where much sediment is deposited on the shallow bed of the sea, whilst it slowly subsides.
Obviously, if the earliest fossiliferous rocks now known are coeval with the commencement of life, and if their contents give us any just conception of the nature and the extent of the earliest fauna and flora, the insignificant amount of modification which can be demonstrated to have taken place in any one group of animals, or plants, is quite incompatible with the hypothesis that all living forms are the results of a necessary process of progressive development, entirely comprised within the time represented by the fossiliferous rocks.
No Vertebrata as yet discovered in the oldest Fossiliferous Rocks. Objections to the Theory of Progression considered. Causes of the Popularity of the Doctrine of Progression as compared to that of Transmutation.
Considering the difference in latitude between these several places, and the small number of species altogether collected, namely thirty-six, I conceive the above proportional number of species in common, is sufficient to show that the lower fossiliferous mass belongs nearly, I do not say absolutely, to the same epoch.
On the absence of intermediate varieties at the present day On the nature of extinct intermediate varieties; on their number On the lapse of time, as inferred from the rate of denudation and of deposition number On the lapse of time as estimated by years On the poorness of our palaeontological collections On the intermittence of geological formations On the denudation of granitic areas On the absence of intermediate varieties in any one formation On the sudden appearance of groups of species On their sudden appearance in the lowest known fossiliferous strata Antiquity of the habitable earth.
We can thus, also, understand the general want of that close sequence in fossiliferous formations which we might theoretically have anticipated; for, without we suppose a subsiding movement to go on at the same spot during an enormous period, from one geological era to another, and during the whole of this period sediment to accumulate at the proper rate, so that the depth should not become too great for the continued existence of molluscous animals, it is scarcely possible that there should be a perfect sequence at the same spot in the fossil shells of the two geological formations.
Many gigantic specimens of the Ostraea Patagonica were collected in the Gulf of St. George. A good section of the lowest fossiliferous mass, about forty feet in thickness, resting on claystone porphyry, is exhibited a few miles south of the harbour. The shells sufficiently perfect to be recognised consist of: Pecten Paranensis, d'Orbigny, "Voyage, Pal." Nucula ornata, G.B. Sowerby. 6.
What then does an impartial survey of the positively ascertained truths of palæontology testify in relation to the common doctrines of progressive modification, which suppose that modification to have taken place by a necessary progress from more to less embryonic forms, or from more to less generalized types, within the limits of the period represented by the fossiliferous rocks?
Not only may any kind of fossiliferous rocks occur next to the Archæan, but even the "youngest" may be so metamorphosed and crystalline as to resemble exactly in this respect the so-called "oldest" rocks.
Near Cromer, blocks of granite from 6 to 8 feet in diameter have been met with, and smaller ones of syenite, porphyry, and trap, besides the wreck of the London Clay, Chalk, Oolite, and Lias, mixed with more ancient fossiliferous rocks. Erratics of Scandinavian origin occur chiefly in the lower portions of the till.
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