42 PROCEEDINGS OK THE A N A I ( )M K'Al, AND ANTHROPOLOGICAL 



that of the Stone ami Bron/e, as hatchets of copper have been found 

 in the Danish peat in such positions as to give rise to this supposition. 



The next stage of improvement that manifested by the substitu- 

 tion of iron for bronze indicates a vast stride in the progress of the 

 arts, for iron does not, practically speaking, present itself in a native 

 state, so that to recognise its ores and then to separate the metal 

 demands no small exercise of the powers of observation and invention. 

 Also to fuse the ore requires an intense heat not to be obtained 

 without artificial means, such as blow-pipes, bellows or some other 

 suitable machinery. 



Besides the peat mosses another class of memorials found in 

 Denmark has thrown light on the prehistoric stage. Along the 

 shores of nearly all the Danish islands mounds may be seen con- 

 sisting chiefly of thousands of shells of the oyster, cockle, and other 

 molluscs. These shells are plentifully mixed up with bones of 

 various quadrupeds, birds and fish which served as the food of the 

 rude hunters and fishers by whom the mounds were accumulated. 

 Such accumulations are called by the Danes " kitchen-refuse heaps ". 

 Scattered all through them are Hint knives, hatchets and other imple- 

 ments of stone, horn, wood, and bone, with fragments of coarse 

 pottery mixed with charcoal, but no implements of bronze or iron. 

 The stone knives and hatchets have been sharpened by rubbing, 

 and are a degree less rude than those of an older date found 

 in France associated with the bones of long-extinct mammalia. 

 The mounds vary in height from 3 to 10 feet, and some of them 

 are as much as 1,000 feet long and from 150 to 200 feet wide. 

 These mounds are of great age as shown not only by the stone 

 implements found in them but also by the geographical fact that they 

 are not found along the shores bathed by the German Ocean, where 

 the waves are slowly eating away the land. Even stronger evidence 

 of their great age is furnished by the character of their embedded 

 shells. The oyster cannot live in the Baltic Sea now owing to the 

 water not containing a sufficiency of salt, and the cockle, mussel and 

 periwinkle attain only a third of their natural size from the same 



