ual evolution of human culture. The lower strata in these great bowls were found to be made up chiefly of mosses and various plants matted together with the trunks of fallen trees, sometimes of very large diameter; and the botanical examination of the lowest layer of these trees and plants in the various bowls revealed a most important fact: for this layer, the first in point of time, was always of the Scotch fir—which now grows nowhere in the Danish islands, and can not be made to grow anywhere in them—and of plants which are now extinct in these regions, but have retreated within the Arctic Circle. Coming up from the bottom of these great bowls there was found above the first layer a second, in which were matted together masses of oak-trees of different varieties; these, too, were relics of a bygone epoch, since the oak has almost entirely disappeared from Denmark. Above these came a third stratum made up of fallen beech-trees, and the beech is now the most common tree of the Danish Peninsula.
And now came a second fact of the utmost importance as connected with the first: scattered, as a rule, through the lower of these deposits, that of the extinct fir-trees and plants, were found implements and weapons of smooth stone; in the layer of oak-trees were found implements of bronze; and among the layer of beeches were found implements and weapons of iron.
The general result of these investigations in these two sources, the shell mounds and the peat deposits, was the same: the first civilization evidenced in them was marked by the use of stone implements more or less smooth, showing a progress from the earlier rude Stone period made known by the bone caves; then came a later progress to a higher civilization, marked by the use of bronze implements; and, finally, a still higher development when iron began to be used.
The labors of the Danish archæologists have resulted in the formation of a great museum at Copenhagen, and on the specimens they have found, coupled with those of the drift and bone caves, is based the classification between the main periods or divisions in the evolution of the human race above referred to.
It was not merely in Scandinavian lands that these results were reached; substantially the same discoveries were made in Ireland and France, in Sardinia and Portugal, in Japan and in Brazil, in Cuba and in this country; in fact, as a rule, in nearly every part of the world which was thoroughly examined.
- For the general subject, see Mortillet, Le Préhistorique, p. 498, et passim. For examples of the rude stone implements, improving as we go from earlier to later layers in the bone eaves, see Boyd Dawkins, Early Man in Britain, chap, vii, p. 186; also Quatrefages, Human Species, New York, 1879, pp. 305 et seq. An interesting gleam of light is thrown on the subject in De Baye, Grottes Préhistoriques de la Marne, pp. 31 et seq.; also Evans, as cited in the previous chapter. For the more recent investigations in the Danish shell-heaps, see