It is different with the objects found in the peat-mosses, and especially in those which the Danes call skovmoses, that is, forest mosses. These formations are found in hollows of irregular form which have been excavated in Quaternary clays, reaching at times a depth of thirty feet or more. The detailed study which Steenstrup especially has made of them led him to distinguish among them the central region or peat-moss, and the exterior region or forest region.
The first is formed by the cavity itself. It is the peat-moss properly so called, formed by the layers of peat which fill the cavity, and have been deposited subsequently to its formation. A meagre vegetation grew upon the surface, which divides this mass of vegetable débris into distinct zones. They are, proceeding downwards:—1st, certain trees, such as the birch, alder, and hazel, etc., mixed with heaths; 2nd, small stunted, but sturdy pines (Pinus sylvestris), which had grown upon peat in which mosses of a high organisation, such as the hypnum, were found; 3rd, compact, amorphous peat, the elements of which for a long time it was considered impossible to discover, but in which MM. Steenstrup and Nathorst discovered in 1872 undoubted remains of five species of plants now confined to the Arctic circle, such as, Salix herbacea, S. polaris, S. reticulata, Betula nana, Dryas octopetala; 4th, a bed of clay evidently resulting from material washed down by rain from the sides of the hollow, when the latter were still bare.
The forest region occupies the sides themselves. The trees were there protected from the wind, and extending their roots into a fertile clay they attained a magnificent development. Now we at once meet with a very remarkable fact, the beech tree is not found in the skovmoses. At the present day it is the essential constituent of the Danish forests; it is the national tree, and the most ancient traditions give no suspicion that it has ever been wanting in Denmark. In its place the peat-mosses contain at first nothing but oaks (Quercus robur sessilifolia) which disappeared from the country in prehistoric times, and is only found in a few places in Jutland. Then, as we descend deeper into the peat, the oaks give way to pines. In their turn the latter gain the ascendant, and occupy the lowest parts of the peat exclusively.
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.
This fact is again proved by the discovery of a human station, made by M. Fraas, at Schussenried in Wurtemberg. Here man, whose presence is attested by worked flints of various forms, by weapons and instruments of bone, by phalanges of reindeer made into whistles, lived with the reindeer, the glutton, and the polar fox, and gathered mosses which are now confined to Northern Europe, such as Hypnum sarmentosum, fluitans, and aduncum. As in Denmark, he seems to have followed the glaciers step by step, as the melting of the latter opened out new lands to his activity.
IV. Without claiming such accuracy for the historic dates, or even such an approximation as that derived from the Aryan traditions on the most ancient monuments of Egypt, is it possible to estimate the number of years which have elapsed since the times we have just been discussing?
This question has often attracted the attention of geologists and anthropologists, and several attempts have been made to solve it. But the results are still far from being satisfactory. They are none the less interesting, and calculated, to a certain extent, to encourage fresh research. The method is good; it has only been hitherto wanting in sufficiently precise dates, and we may hope that they will be sooner or later forthcoming.