OF THE EARTH.
It does not appear, on reflection, that any other proba ble cause can be assigned for a total destruction of marine animals; as we have no reason whatever to suppose a change in the chemical constitution of the ocean; and as, whatever changes the general surface may have under gone by the partial elevation of strata, it is evident that an ocean still remained, although under a different state of distribution. It has been conjectured that this early creation was limited to marine beings; but it was already shown that our proofs on this subject were of a negative nature, and insufficient to establish that point. \Ve need not recur to that question, nor to that which relates to the extinction of genera or of species, as it was sufficiently examined already; but if the argillaceous schists which are said to contain vegetable remains are really primary, the question, as far as it relates to that point, is determined.
As, from the unconformable position of the second ary strata on the primary, in many instances, it is certain that, even after that first derangement which elevated the latter, they must often have remained under water during the deposition of the secondary, it becomes more doubtful whether the earliest races were destroyed, unless such a change of temperature as that above alluded to took place. It was by a subsequent revolution that the remains which now occupy at least the lower members of the secondary strata were elevated. Yet, when we consider that the coal series, and the upper parts of the secondary strata, give proofs of a distinct set of revolutions, we must remain un certain to what extent the lower secondary strata were ele vated above the waters. That they were so in some in stances, is proved by the existence of land vegetables im mediately above them ; but if that was universally the case, we have no other reasons than in the first revolution, for assuming a total destruction of created beings, even at this interval. The same reasoning, in every respect, it is evident, applies to this case as to the former, whether as it relates to this fact, to the loss of species and genera, or to the existence of vegetables.
When we arrive at the coal deposits, we find marks of a set of revolutions that are very intricate, and that ap pear to have been very partial. Here we have evidences enough of the existence of terrestrial beings, Of plants at least ; although, as already shown, we have still no proofs of the existence of land animals. That these have been
again submerged in many cases, we are certain ; and, further, beneath an ocean, as we find then' followed by strata containing marine fossils. In others, it must yet remain doubtful whether they were submerged after their final elevation from whatever waters they were formed in; as we cannot be certain, in the case of the Scottish coal deposit, for example, whether the same marine strata which now lie above that series in England were ever pre sent above these also. If these revolutions were thus partial, we have no reason to suppose that a general de struction of created beings took place at that period, al though a partial one must have been produced ; so that here also we are left to conjectures that will probably never be reduced to certainties. The evidence on this subject, which consists in the tropical analogies of the sub merged plants, has been shown to he insufficient for this purpose.
The depression of the coal Strata beneath the waters, which is partial as it relates to them, but which, lbr aught we know to the contrary, may have been parts of a general revolution, is followed by the extensive deposit of the red marl, and of the calcareous beds called lias; which latter contain not only marine shells, but amphibious animals and vegetable fragments that appear to have been deposit ed in them by alluvia, and which therefore prove that some dry land remained at the catastrophe which depress ed the coal strata. The numbers of genera and species here begin to increase ; and therefore it has been supposed that either a new, or a progressively augmenting creation took place. But it must here be remembered that this evidence is inconclusive; because the stratum in question has escaped many revolutions which the earlier rocks un derwent, and because many other circumstances, against the existence of which we cannot decide, might have modified the earlier depositions of animal remains so as to vitiate this partial testimony. That which is here said applies to the whole of the secondary strata as far as the chalk ; as the order of these is consecutive, and as the whole appear to have been formed during one period of repose.