Page:Antiquity of Man as Deduced from the Discovery of a Human Skeleton.djvu/28

22 feet thick, exclusively consists. I need hardly remark that the species of Sphagnum, a genus which contributes most to bog-formations, are mosses that grow in air; they send their roots most abundantly in swampy, clayey soils. Here the plant testifies, as does the man three strata below, to the nature of the atmosphere in which they lived and breathed.

After 3⋅58 feet vertical thickness had been thus attained the ground again subsided, again became overflowed, and again received deposits of mud to nearly four feet of vertical thickness (no. 5). Then, again, the water recedes or the land rises, and exposes to the atmosphere a surface overgrown by air-breathing plants. But the thickness of the stratum, 4, testifies to a briefer period of dry or boggy land at this locality; for, before two feet of pure peat had been formed, a stratum of mixed mud and peat, nearly two feet thick (no. 3), is overlaid. This then subsides to receive ten vertical feet thickness of unmixed mud (no. 2). In the course of subsidence changes in the land-surfaces wasted by the then fluvial current lead to a final deposit of six feet thickness of clay (no. 1), which now supports the marshy level at which the Dock-excavations commenced. They have extended, since the discovery of the skeleton, to the bottom of the black-sand deposits, which rest upon the gravel-bed known as "ballast," in which flint implements are more commonly found.

Let any equal mind, receptive of evidence to be judged on its own, exclusive, merits, without prepossessing bias, attempt to conceive the difference between the recorded lapse of time since the actual surface was first trod by a Roman soldier and the lapse of unrecorded time since the