In the seventh place, numerous races of animals and plants must have occupied the globe previous to those which now inhabit it, and have successively passed away, as catastrophes occurred, or the climate became unfit for their residence. Not less than thirty thousand species have already been dug out of the rocks; and excepting a few hundred species, mostly of sea shells, occurring in the uppermost rocks, none of them correspond to those now living on the globe. In Europe, they are found to the depth of about six and a half miles; and in this country, deeper; and no living species is found more than one twelfth of this depth. All the rest are specifically and often generically unlike living species; and the conclusion seems irresistible, that they must have lived and died before the creation of the present species. Indeed, so different was the climate in those early times,--it having been much warmer than at present in most parts of the world,--that but few of the present races could have lived then. Still further: it appears that, during the whole period since organized beings first appeared on the globe, not less than four, or five, and probably more--some think as many as ten or twelve--entire races have passed away, and been succeeded by recent ones; so that the globe has actually changed all its inhabitants half a dozen times. Yet each of the successive groups occupied it long enough to leave immense quantities of their remains, which sometimes constitute almost entire mountains. And in general, these groups became extinct in consequence of a change of climate; which, if imputed to any known cause, must have been an extremely slow process. Now, these results are no longer to be regarded as the dreams of fancy, but the legitimate deductions from long and careful observation of facts. And can any reasonable man conceive how such changes can have taken place since the six days of creation, or within the last six thousand years? In order to reconcile them with such a supposition, we must admit of hypotheses and absurdities more wild and extravagant than have ever been charged upon geology. But admit of a long period between the first creative act and the six days, and all difficulties vanish. In the eighth place, the denudations and erosions that have taken place on the earth's surface indicate a far higher antiquity to the globe, even since it assumed essentially its present condition, than the common interpretation of Genesis admits. The geologist can prove that in many cases the rocks have been worn away, by the slow action of the ocean, more than two miles in depth in some regions, and those very wide; as in South Wales, in England. As the continents rose from the ocean, the slow drainage by the rivers has excavated numerous long and deep gorges, requiring periods incalculably extended.