488 PREHISTORIC EUROPE. 



to six feet or more. To this bed succeeds a second forest-layer 

 composed of the stools and trunks of Scots firs and birches, 

 which in their turn are buried under overlying peat, which may 

 be as thick as the peat below. Mr. Axel Blytt says there are 

 perhaps even more than two buried forest-layers, but certainly 

 two would seem to be the common number. It is worthy of 

 note that in the Norwegian bogs the oak-forests underlie the 

 pine-forests, and the same is the case in the peat of Sweden, 

 according to Lindeberg and Olbers. Blytt remarks that the 

 bogs of Norway prove that the bare sea-coast, where now scarcely 

 a tree grows, was once clothed with forests all the way from 

 Lister to Nordvaranger, in East Finmark. Not only, he says, 

 has the Scots fir formerly grown still farther to the north, but 

 it also at one time reached a greater elevation in the mountains, 

 for its remains occur in bogs above the limits attained by the 

 tree at present. Sometimes, indeed, it grew in places where not 

 even the birch is now to be found. According to Blytt, the 

 succession of changes to which the peat-bogs bear witness is as 

 follows: — 1st, A wet period, when bog-mosses formed the bottom- 

 peat, which in some places underlies the older of the two forest- 

 beds. 2d, A genial period, when all the low grounds were 

 covered with a thick growth of oak, hazel, ash, and other trees, 

 and when the horizontal and vertical range of the forests was 

 much greater than it is now. 3d, A wet, ungenial period, during 

 which bog-mosses and other moisture-loving plants increased 

 abundantly, while the trees at the same time, ceasing to flourish, 

 fell, and sooner or later were buried in the accumulating peat. 

 4th, A return of drier conditions, when the bogs no longer increased 

 so generally, but dried up and allowed trees to grow upon their 

 surface. The forests which at this time overspread the country 

 were formed of great coniferous trees, 1 that enjoyed a much 

 more extensive horizontal and vertical range than the same trees 

 do now. 5th, Another wet period succeeded, when the forests 

 decayed as before and were gradually overwhelmed by a renewed 



1 Blytt mentions stumps that measured 12 feet in circumference. In one 

 stump with a girth of 6 feet he counted 200 rings of growth. 



