Oaks and pines, when they fell from old age, accident, or human agency, generally fell towards the interior of the bog. Their interlaced branches supported and consolidated the peat, which was then in the best condition for preserving, as they fell, any solid substances which may have been dropped or thrown into the bog. Man used to frequent the skovmoses, and it is well known that he cannot live in any place without losing a number of objects, even those upon which he sets most value. He lost in the bogs weapons, tools, and instruments of all kinds, and they all remain where they fell. The skovmoses have thus become a kind of chronologically stratified museum, where each generation has left its trace in the contemporaneous peat. We have only to explore it layer by layer to obtain many definite ideas about the predecessors of the present Danes, and to find in this prehistoric past _relative dates_ or _epochs_. In this manner the Scandinavian savants have arrived at the idea of the _Ages of Iron_, _Bronze_, and _Stone_, which are now universally adopted. I shall not here follow the development which these fundamental ideas have received, nor the manner in which they have been applied to the _Lake dwellings_ of Switzerland and elsewhere. I shall not insist further upon the different degrees of civilization betrayed by the use of two metals and of polished or ground stone. I shall confine myself to the remark that in Denmark the Iron age entirely corresponds with that of the beech tree, while the Bronze age corresponds with the entire period of the oak, and the close of that to the pine. Lastly, the pine is the tree of the Stone age. The presence of objects formed by human industry proves the presence of man. Thanks to their irrefutable testimony, there is no difficulty in tracing him through the zones of the oak and the pine. The immense number of objects, which have been left by him in the peat period, points to the existence of a somewhat dense population. These objects, on the contrary, become very rare, and at the same time ruder, in the layer of amorphous peat. They were, for some time, even thought to be wanting altogether, till they were finally discovered by Steenstrup associated with the remains of the reindeer. Man, then, was living in Denmark when Arctic plants, such as _Betula nana_ and _Salise polaris_ grew at the bottom of the skovmoses; he was accompanied by the reindeer, which completes the resemblance between the past state of that country and the present state of Lapland. Now we know that such a state of things could only have existed in Denmark in the latter part of the Quaternary epoch, when the ice, retreating from the south northwards, would still be far removed from its present limits. We can then affirm that man existed and lived in Europe at the very dawn of the present geological epoch.