210 FOREST LANDS OF NORTHERN RUSSIA. 



latter frequented the low-lying places, and more especially 

 the littoral depressions, where the fresh water coming from 

 the interior accumulated, and gave rise to lagoons as vast 

 in extent as they were shallow in depth. The Arctic 

 lands, which did not then differ in heat or climate from 

 those of our latitudes, produced, beyond all doubt, both of 

 these two kinds of vegetables, of which the one is well 

 known to us, thanks to the multitude of imprints which 

 the coal deposits have preserved, though the other has 

 scarcely left itself visible through the extreme rarity of 

 debt is capable of attesting its ancient existence. 



' The carboniferous age must have been one of enormous 

 duration, although we cannot for one moment suppose this 

 to have equalled that of the' Silurian. The Devonian 

 period serves as a transition between them, and leads by 

 insensible degrees from one to the other. The ocean was 

 then immense in its area, and the emerged land, more 

 extensive than one is at first disposed to admit, composed 

 only primitive crystalline regions. Without being strongly 

 marked in profile, or offering an ossature established on a 

 very large bcale, these palaeozoic lands had, however, a 

 certain elevated contour ; and the coast-line must have 

 been marked out with some measure of distinctness. It 

 is to emersions produced from many reprisals in such a 

 way as to draw each time from the waters a low girdle 

 around the continents of the epoch, that are due in reality 

 the formations of coal, and the deposits in which these are 

 found. Elsewhere it is always along the shore-line, and 

 most frequently on the marine formations immediately 

 anterior to their production, that these coal basins have 

 established themselves. And in this respect we see well, 

 by the descriptions of Dr Heer, arid by the indications 

 given by the celebrated Swedish explorer, Nordenskjoeld, 

 that the Arctic localities differ in nothing, so far as their 

 conditions can be determined, from those which have been 

 observed on Europe belonging to the same period. The 

 most remote in time of these emersions following deposits 

 of coal and of carbonaceous schists, with vegetable imprints, 



