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 
débris 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 scale, 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, and 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 carhonaceous schists, with vegetable imprints, 
