We have already, in previous chapters, noticed the parallelism of the succession of life in the earth as revealed in Genesis with that disclosed by geology; but this subject must be farther referred to in the sequel, and in the mean time the reader may compare for himself the succession of life in the table with that in the later creative days. 5. The lapse of time embraced in the geological history of the earth is enormous. Fully to appreciate this it is necessary to study the science in detail, and to explore its phenomena as disclosed in actual nature. A few facts, however, out of hundreds which might have been selected, will suffice to indicate the state of the case. The delta and alluvial plain of the Mississippi have an area of more than 12,000 square miles, and must have an average depth of about 800 feet. At the present rate of conveyance of sediment by the river, it has been calculated that a period of about 33,000 years is implied in the deposition of this comparatively modern formation.[143] To be quite safe, let us take 30,000 years, and add 50,000 more for the remainder of the Post-pliocene or Quaternary. We may then safely multiply this number by forty, for the length of the Tertiary period. We may add three times as much for the Mesozoic period, and this will be far under the truth. It will then be quite safe to assume that the Palaeozoic period was three times as long as the Mesozoic and Tertiary together. This would give altogether, say, 51,280,000 years for the whole of geological time from the beginning of the Palaeozoic, leaving the duration of the Eozoic and previous periods undetermined, but requiring perhaps nearly as much time. Great though these demands may seem, they would be probably far below the rigid requirements of the case were it not for the probability that the present rate of transference of material by the great river is less than it was in Post-pliocene and early modern times. This might enable us to reduce our estimate considerably within the scope of a hundred millions of years.[144] Take another illustration from an older formation. An excellent coast section at the Joggins, in Nova Scotia, exhibits in the coal formation proper a series of beds with erect trunks and roots of trees _in situ_, amounting to nearly 100. About 100 forests have successively grown, partially decayed, and been entombed in muddy and sandy sediment. In the same section, including in all about 14,000 feet of beds, there are 76 seams of coal, each of which can be proved to have taken more time for its accumulation than that required for the growth of a forest. Supposing all these separate fossil soils and coals to have been formed with the greatest possible rapidity, forty thousand years would be a very moderate calculation for this portion of the Carboniferous system; and for aught that we know thousands of years may be represented by a single fossil soil. But this is the age