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CHAPTER II.

RECENT PERIOD- DANISH PEAT AND SHELL MOUNDS -SWISS

LAKE DWELLINGS.

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

TED - NO EXTINCT SPECIES — CHRONOLOGICAL COM-
PUTATIONS 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. W HEN treating in the · Principles of Geology of the

W changes of the earth which have taken place in comparatively modern times, I have spoken (chap. xlv.) 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 bumid 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 enquiries 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

* 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 Société Vaudoise des Sci. Nat., t. vi. Lausanne, 1860.

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ten to thirty feet, have been formed in hollows or depressions in the northern drift or boulder formation hereafter to be described. The lowest stratum, two to three 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 three 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 fourish in Denmark. All the land and fresh-water shells, and all the mammalia as well as the plants, whose remains occur buried in the Danish peat, are of recent species.

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 shellmounds of the aborigines presently to be described, the Danish and Swedish antiquaries and naturalists, MM. Nilsson, Steenstrup, Forchhammer, Thomsen, Worsäae 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.*

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

* Morlot, Bulletin de la Société Vaudoise des Sci. Nat., t. vi. p. 292.

CHAP. II.

WORKS OF ART IN DANISH PEAT-MOSSES.

ten to thirty feet, have been formed in hollows or depressions in the northern drift or boulder formation hereafter to be described. The lowest stratum, two to three 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 three 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 fresh-water shells, and all the mammalia as well as the plants, whose remains occur buried in the Danish peat, are of recent species.

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 shellmounds of the aborigines presently to be described, the Danish and Swedish antiquaries and naturalists, MM. Nilsson, Steenstrup, Forchhammer, Thomsen, Worsäae 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.*

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

* Morlot, Bulletin de la Société Vaudoise des Sci. Nat., t. vi. p. 292.

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