CHAPTER 2. — RECENT PERIOD—DANISH PEAT AND SHELL MOUNDS—SWISS

LAKE-DWELLINGS.

Plate 1. A Village Built on Piles in A Swiss Lake

(Restored by Dr. F. Keller, partly from Dumont D'Urville's

Sketch of similar habitations in New Guinea.)

Works of Art in Danish Peat-Mosses.

Remains of three Periods of Vegetation in the Peat.

Ages of Stone, Bronze, and Iron.

Shell-Mounds or ancient Refuse-Heaps of the Danish Islands.

Change in geographical Distribution of Marine Mollusca

since their Origin.

Embedded Remains of Mammalia of Recent Species.

Human Skulls of the same Period.

Swiss Lake-Dwellings built on Piles.

Stone and Bronze Implements found in them.

Fossil Cereals and other Plants.

Remains of Mammalia, wild and domesticated.

No extinct Species.

Chronological Computations of the Date of the Bronze and

Stone Periods in Switzerland.

Lake-Dwellings, or artificial Islands called "Crannoges,"

in Ireland.

WORKS OF ART IN DANISH PEAT.

When treating in the "Principles of Geology" of the changes of the earth which have taken place in comparatively modern times, I have spoken of the embedding of organic bodies and human remains in peat, and explained under what conditions the growth of that vegetable substance is going on in northern and humid climates. Of late years, since I first alluded to the subject, more extensive investigations have been made into the history of the Danish peat-mosses. Of the results of these inquiries I shall give a brief abstract in the present chapter, that we may afterwards compare them with deposits of older date, which throw light on the antiquity of the human race.

The deposits of peat in Denmark,* varying in depth from 10 to 30 feet, have been formed in hollows or depressions in the northern drift or boulder formation hereafter to be described.(* An excellent account of these researches of Danish naturalists and antiquaries has been drawn up by an able Swiss geologist, M. A. Morlot, and will be found in the "Bulletin de la Societe Vaudoise des Sci. Nat." tome 6 Lausanne 1860.) The lowest stratum, 2 to 3 feet thick, consists of swamp-peat composed chiefly of moss or sphagnum, above which lies another growth of peat, not made up exclusively of aquatic or swamp plants. Around the borders of the bogs, and at various depths in them, lie trunks of trees, especially of the Scotch fir (Pinus sylvestris), often 3 feet in diameter, which must have grown on the margin of the peat-mosses, and have frequently fallen into them. This tree is not now, nor has ever been in historical times, a native of the Danish Islands, and when introduced there has not thriven; yet it was evidently indigenous in the human period, for Steenstrup has taken out with his own hands a flint instrument from below a buried trunk of one of these pines.

It appears clear that the same Scotch fir was afterwards supplanted by the sessile variety of the common oak, of which many prostrate trunks occur in the peat at higher levels than the pines; and still higher the pedunculated variety of the same oak (Quercus robur, L.) occurs with the alder, birch (Betula verrucosa, Ehrh.), and hazel. The oak has now in its turn been almost superseded in Denmark by the common beech. Other trees, such as the white birch (Betula alba), characterise the lower part of the bogs, and disappear from the higher; while others again, like the aspen (Populus tremula), occur at all levels, and still flourish in Denmark. All the land and freshwater shells, and all the mammalia as well as the plants, whose remains occur buried in the Danish peat, are of Recent species.[Note 3]

It has been stated, that a stone implement was found under a buried Scotch fir at a great depth in the peat. By collecting and studying a vast variety of such implements, and other articles of human workmanship preserved in peat and in sand-dunes on the coast, as also in certain shell-mounds of the aborigines presently to be described, the Danish and Swedish antiquaries and naturalists, MM. Nilsson, Steenstrup, Forchhammer, Thomsen, Worsaae, and others, have succeeded in establishing a chronological succession of periods, which they have called the ages of stone, of bronze, and of iron, named from the materials which have each in their turn served for the fabrication of implements.

The age of stone in Denmark coincided with the period of the first vegetation, or that of the Scotch fir, and in part at least with the second vegetation, or that of the oak. But a considerable portion of the oak epoch coincided with "the age of bronze," for swords and shields of that metal, now in the Museum of Copenhagen, have been taken out of peat in which oaks abound. The age of iron corresponded more nearly with that of the beech tree.*

(* Morlot "Bulletin de la Societe Vaudoise des Sci. Nat."

tome 6 page 292.) [Note 4]

M. Morlot, to whom we are indebted for a masterly sketch of the recent progress of this new line of research, followed up with so much success in Scandinavia and Switzerland, observes that the introduction of the first tools made of bronze among a people previously ignorant of the use of metals, implies a great advance in the arts, for bronze is an alloy of about nine parts of copper and one of tin; and although the former metal, copper, is by no means rare, and is occasionally found pure or in a native state, tin is not only scarce but never occurs native. To detect the existence of this metal in its ore, then to disengage it from the matrix, and finally, after blending it in due proportion with copper, to cast the fused mixture in a mould, allowing time for it to acquire hardness by slow cooling, all this bespeaks no small sagacity and skilful manipulation. Accordingly, the pottery found associated with weapons of bronze is of a more ornamental and tasteful style than any which belongs to the age of stone.

Some of the moulds in which the bronze instruments were cast, and "tags," as they are called, of bronze, which are formed in the hole through which the fused metal was poured, have been found. The number and variety of objects belonging to the age of bronze indicates its long duration, as does the progress in the arts implied by the rudeness of the earlier tools, often mere repetitions of those of the stone age, as contrasted with the more skilfully worked weapons of a later stage of the same period.

It has been suggested that an age of copper must always have intervened between that of stone and bronze; but if so, the interval seems to have been short in Europe, owing apparently to the territory occupied by the aboriginal inhabitants having been invaded and conquered by a people coming from the East, to whom the use of swords, spears, and other weapons of bronze was familiar. Hatchets, however, of copper have been found in the Danish peat.

The next stage of improvement, or that manifested by the substitution of iron for bronze, indicates another stride in the progress of the arts. Iron never presents itself, except in meteorites, in a native state, so that to recognise its ores, and then to separate the metal from its matrix, demands no inconsiderable exercise of the powers of observation and invention. To fuse the ore requires an intense heat, not to be obtained without artificial appliances, such as pipes inflated by the human breath, or bellows, or some other suitable machinery.

DANISH SHELL-MOUNDS, OR KJOKKENMODDING.*

(* Mr. John Lubbock published, after these sheets were

written, an able paper on the Danish "Shell-mounds" in the

October number of the "Natural History Review" 1861 page

489, in which he has described the results of a recent visit

to Denmark, made by him in company with Mr. Busk.)

In addition to the peat-mosses, another class of memorials found in Denmark has thrown light on the pre-historical age. At certain points along the shores of nearly all the Danish islands, mounds may be seen, consisting chiefly of thousands of cast-away shells of the oyster, cockle, and other molluscs of the same species as those which are now eaten by Man. These shells are plentifully mixed up with the bones of various quadrupeds, birds, and fish, which served as the food of the rude hunters and fishers by whom the mounds were accumulated. I have seen similar large heaps of oysters, and other marine shells with interspersed stone implements, near the seashore, both in Massachusetts and in Georgia, U. S. A., left by the native North American Indians at points near to which they were in the habit of pitching their wigwams for centuries before the white man arrived.

Such accumulations are called by the Danes, Kjokkenmodding, or "kitchen-middens." Scattered all through them are flint knives, hatchets, and other instruments of stone, horn, wood, and bone, with fragments of coarse pottery, mixed with charcoal and cinders, but never any implements of bronze, still less of iron. The stone hatchets and knives had been sharpened by rubbing, and in this respect are one degree less rude than those of an older date, associated in France with the bones of extinct mammalia, of which more in the sequel. The mounds vary in height from 3 to 10 feet, and in area are some of them 1000 feet long, and from 150 to 200 wide. They are rarely placed more than 10 feet above the level of the sea, and are confined to its immediate neighbourhood, or if not (and there are cases where they are several miles from the shore), the distance is ascribable to the entrance of a small stream, which has deposited sediment, or to the growth of a peaty swamp, by which the land has been made to advance on the Baltic, as it is still doing in many places, aided, according to Puggaard, by a very slow upheaval of the whole country at the rate of 2 or 3 inches in a century.

There is also another geographical fact equally in favour of the antiquity of the mounds, namely, that they are wanting on those parts of the coast which border the Western Ocean, or exactly where the waves are now slowly eating away the land. There is every reason to presume that originally there were stations along the coast of the North Sea as well as that of the Baltic, but by the gradual undermining of the cliffs they have all been swept away.

Another striking proof, perhaps the most conclusive of all, that the "kitchen-middens" are very old, is derived from the character of their embedded shells. These consist entirely of living species; but, in the first place, the common eatable oyster is among them, attaining its full size, whereas the same Ostrea edulis cannot live at present in the brackish waters of the Baltic except near its entrance, where, whenever a north-westerly gale prevails, a current setting in from the ocean pours in a great body of salt water. Yet it seems that during the whole time of the accumulation of the "kitchen-middens" the oyster flourished in places from which it is now excluded. In like manner the eatable cockle, mussel, and periwinkle (Cardium edule, Mytilus edulis, and Littorina littorea), which are met with in great numbers in the "middens," are of the ordinary dimensions which they acquire in the ocean, whereas the same species now living in the adjoining parts of the Baltic only attain a third of their natural size, being stunted and dwarfed in their growth by the quantity of fresh water poured by rivers into that inland sea.*

(* See "Principles of Geology" chapter 30.)

Hence we may confidently infer that in the days of the aboriginal hunters and fishers, the ocean had freer access than now to the Baltic, communicating probably through the peninsula of Jutland, Jutland having been at no remote period an archipelago. Even in the course of the nineteenth century, the salt waters have made one irruption into the Baltic by the Lymfiord, although they have been now again excluded. It is also affirmed that other channels were open in historical times which are now silted up.*

(* See Morlot "Bulletin de la Societe Vaudoise des Sci.

Nat." tome 6.)

If we next turn to the remains of vertebrata preserved in the mounds, we find that here also, as in the Danish peat-mosses, all the quadrupeds belong to species known to have inhabited Europe within the memory of Man. No remains of the mammoth, or rhinoceros, or of any extinct species appear, except those of the wild bull (Bos urus, Linn., or Bos primigenius, Bojanus), which are in such numbers as to prove that the species was a favourite food of the ancient people. But as this animal was seen by Julius Caesar, and survived long after his time, its presence alone would not go far to prove the mounds to be of high antiquity. The Lithuanian aurochs or bison (Bos bison, L., Bos priscus, Boj.), which has escaped extirpation only because protected by the Russian Czars, surviving in one forest in Lithuania) has not yet been met with, but will no doubt be detected hereafter, as it has been already found in the Danish peat. The beaver, long since destroyed in Denmark, occurs frequently, as does the seal (Phoca Gryppus, Fab.), now very rare on the Danish coast. With these are mingled bones of the red deer and roe, but the reindeer has not yet been found.

There are also the bones of many carnivora, such as the lynx, fox, and wolf, but no signs of any domesticated animals except the dog. The long bones of the larger mammalia have been all broken as if by some instrument, in such a manner as to allow of the extraction of the marrow, and the gristly parts have been gnawed off, as if by dogs, to whose agency is also attributed the almost entire absence of the bones of young birds and of the smaller bones and softer parts of the skeletons of birds in general, even of those of large size. In reference to the latter, it has been proved experimentally by Professor Steenstrup, that if the same species of birds are now given to dogs, they will devour those parts of the skeleton which are missing, and leave just those which are preserved in the old "kitchen-middens."

The dogs of the mounds, the only domesticated animals, are of a smaller race than those of the bronze period, as shown by the peat-mosses, and the dogs of the bronze age are inferior in size and strength to those of the iron age. The domestic ox, horse, and sheep, which are wanting in the mounds, are confined to that part of the Danish peat which was formed in the ages of bronze and iron.

Among the bones of birds, scarcely any are more frequent in the mounds than those of the auk (Alca impennis), now extinct. The Capercailzie (Tetrao urogallus) is also met with, and may, it is suggested, have fed on the buds of the Scotch fir in times when that tree flourished around the peat-bogs. The different stages of growth of the roedeer's horns, and the presence of the wild swan, now only a winter visitor, have been appealed to as proving that the aborigines resided in the same settlements all the year round. That they also ventured out to sea in canoes such as are now found in the peat-mosses, hollowed out of the trunk of a single tree, to catch fish far from land, is testified by the bony relics of several deep-sea species, such as the herring, cod, and flounder. The ancient people were not cannibals, for no human bones are mingled with the spoils of the chase. Skulls, however, have been obtained not only from peat, but from tumuli of the stone period believed to be contemporaneous with the mounds.

These skulls are small and round, and have a prominent ridge over the orbits of the eyes, showing that the ancient race was of small stature, with round heads and overhanging eyebrows—in short, they bore a considerable resemblance to the modern Laplanders. The human skulls of the bronze age found in the Danish peat, and those of the iron period, are of an elongated form and larger size. There appear to be very few well-authenticated examples of crania referable to the bronze period—a circumstance no doubt attributable to the custom prevalent among the people of that era of burning their dead and collecting their bones in funeral urns.

No traces of grain of any sort have hitherto been discovered, nor any other indication that the ancient people had any knowledge of agriculture. The only vegetable remains in the mounds are burnt pieces of wood and some charred substance referred by Dr. Forchhammer to the Zostera marina, a sea plant which was perhaps used in the production of salt.

What may be the antiquity of the earliest human remains preserved in the Danish peat cannot be estimated in centuries with any approach to accuracy. In the first place, in going back to the bronze age, we already find ourselves beyond the reach of history or even of tradition. In the time of the Romans the Danish Isles were covered, as now, with magnificent beech forests. Nowhere in the world does this tree flourish more luxuriantly than in Denmark, and eighteen centuries seem to have done little or nothing towards modifying the character of the forest vegetation. Yet in the antecedent bronze period there were no beech trees, or at most but a few stragglers, the country being then covered with oak. In the age of stone again, the Scotch fir prevailed, and already there were human inhabitants in those old pine forests.

How many generations of each species of tree flourished in succession before the pine was supplanted by the oak, and the oak by the beech, can be but vaguely conjectured, but the minimum of time required for the formation of so much peat must, according to the estimate of Steenstrup and other good authorities, have amounted to at least 4000 years; and there is nothing in the observed rate of the growth of peat opposed to the conclusion that the number of centuries may not have been four times as great, even though the signs of Man's existence have not yet been traced down to the lowest or amorphous stratum. As to the "kitchen-middens," they correspond in date to the older portion of the peaty record, or to the earliest part of the age of stone as known in Denmark.

ANCIENT SWISS LAKE-DWELLINGS, BUILT ON PILES.