56 THE MODERN PERIOD. 



period^ when the inhabitants were small-sized men, brachykephalous 

 or short headed, like the modern Lapps, using stone implements, and 

 subsisting by hunting. Then the country, or a considerable part of it, 

 was covered by forests of Scotch fir [Pinus sylvestris). 2c?, A bronze 

 period, in which implements of bronze as well as of stone were used, 

 and the skulls of the people were larger and longer than in the previous 

 period ; while the country seems to have been covered with forests of 

 oak {Quercus rohiu^). ScZ, An iron period, which lasted to the historic 

 times, and in which beech forests replaced those of oak." All of these 

 remains are geologically recent ; and, except the changes in the forests, 

 and of some indigenous animals in consequence, and probably a slight 

 elevation of some parts of Denmark^ no material changes in organic 

 or inorganic nature have occurred. 



The Danish antiquaries have attempted to calculate the age of the 

 oldest of these deposits by considerations based on the growth of peat, 

 and the succession of trees; but these calculations are obviously 

 unreliable. The first forest of pines would, when it attained maturity, 

 naturally be destroyed, as usually happens in America, by forest 

 conflagrations. It might perish in this way in a single summer. The 

 second growth which succeeded would, in America, be birch, poplar, 

 and similar trees, which would form a new and tall forest in half a 

 century ; and in two or three centuries would probably be succeeded 

 by a second permanent forest, wliich in the present case seems to have 

 been of oak. This would be of longer continuance, and would, inde- 

 pendently of human agency, only be rejjlaced by beech, if, in the 

 course of ages, the latter tree proved itself more suitable to the soil, 

 climate, and other conditions. Both oak and beech are of slow ex- 

 tension, their seeds not being carried by the winds, and only to a 

 limited degree by birds. On the other hand, the changes of forests 

 cannot have been absolute or universal. There must have been oak 

 and beech groves even in the pine woods; and the growing and 

 increasing beech woods would be contemporary with the older and 

 decaying oak forest, as this last would probably perish, not by fire, but 

 by decay, and by the competition of the beeches. The growth of peat 

 has also been appealed to in connexion with the succession of forests 

 as affording a mark of time ; but this is very variable even in the same 

 locality. It goes on very rapidly when moisture and other conditions 

 are favourable, and especially when it is aided by wind-falls, drift- 

 wood, or beaver-dams, impeding drainage and contributing to the ac- 

 cumulation of vegetable matter. It is retarded and finally terminated 

 by the rise of the surface above the drainage level, by the clearing of 

 the country, or by the establishment of natural or artificial drainage. 



