Man before metals / by N. Joly.

Nicolas Joly

Date:: 1902

Credit: Man before metals / by N. Joly. Source: Wellcome Collection.

21/384 page 9

$THE ANTIQUITY OF THE HUMAN RACE. CHAPTER 1. THE riiEIIISTORIC AGES. I, GENERAL NOTIONS OP THE STRUCTURE OP THE EARTH. It seems necessary, for the better understanding of the following chapters, to give to those of our readers who are unfamiliar with geological terms, a general idea of the various stages through which our globe has passed before arriving at the condition which it now presents to our view. The immense majority of geologists hold that the earth was originally a mass of incandescent and Huid matter. As it gradually cooh^l an outer crust was formed, and the vapours dispersed in the atmosphere were con- densed upon the surface of the globe, and formed the seas. At the bottom of these original seas the primary rocks and those of the transition period were depositecl. These were followed by those of the tertiary period, which Lyell has divided into eocene, meiocene, and pleiocene;' ' The beds of the tertiary period liave been thus divided by Lycll according to the number of recent shells contained in them as compare*! to the fossil ones. The lowest layer, the eocene beds (tcos, dawn, and »co(><ds, recent), that is, the most ancient deposit of the tertiary epoch, contains only 3i sjjccios per cent, similar to those which now exist. The meiocene, or middle layer {fxuov, less, and Kattis, recent) is that in which the recent shells, less numerous than in the pleiocene, are in the proportion of 17 or 20 per cent, as compared to the extinctspccies. The proportion increases to 40 or 50 per cent, in the upper layer, the pleiocene beds (xAeiov more, and Kaiv6s, recent). An important remark$

Man before metals / by N. Joly.

Licence and re-use

Contents