CHAP. II. WORKS OP ART IN DANISH PEAT-MOSSES. 9 



ten to thirty feet, have been formed in hollows or depres- 

 sions 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 sjjhagnum, 

 above which lies another growth of peat, not made up ex- 

 clusively 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 after- 

 wards 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 Rohur 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 has now in its turn been almost superseded in Denmark by the 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?), characterize the lower part of the bogs, and disappear 

 from the higher; while others, again, like the aspen (Populus 

 tremida), 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 shell- 

 mounds of the aborigines pi-esently to be described, the 



