308 
SILUKIA. 
[Chap. XIII. 
CHAPTEE XIII. 
PEKMIAN KOCKS. 
CHANGES OF THE FORMER SURFACE. ORIGIN OF THE TERM ' PERMIAN ' AS APPLIED TO THE 
HIGHEST GROUP OF PALAEOZOIC DEPOSITS. THE PERMIAN ROCKS OF RUSSIA, GERMANY, AND 
BRITAIN. THE ORGANIC REMAINS OF THE GROUP. 
In the two previous Chapters, slight allusions only have been made to ig- 
neous or volcanic materials ejected and spread out on the sea-bottom con- 
temporaneously with the ordinary sedimentary deposits ; for during the 
Devonian and Carboniferous eras such eruptions were by no means so 
abundant in the British area as when the Lower Silurian rocks were 
accumulated. (See pp. 76 &c.) 
The great Upper Coal-fields considered in the previous Chapter were 
probably, in regions like Britain and America, evolved under conditions 
which geologists would consider comparatively quiescent. This is supposed 
to have been particularly the case with those coal-beds which were formed 
either by continuous depressions of low lands beneath the waters or by 
alternations of subaqueous and terrestrial surfaces. The close, however, of 
that period was specially marked by ruptures of the crust of the earth, 
which, from the physical evidences placed before us, must have extended 
over very distant regions. Whatever may have been the previous changes, 
it was then that the coal-strata and their antecedent formations were very 
generally broken up, by upheavals, into separate troughs and basins, dis- 
torted by numberless powerful dislocations. The order of ancient sedi- 
mentary succession was thus very widely, though not universally, inter- 
rupted ; and all the strata previously spoken of were so disturbed as to 
produce a prevalent break or discordance between the Carboniferous de- 
posits and those which succeeded to them. 
This disturbance, however, was not general, since there are exceptional 
tracts in which the Carboniferous and overlying Permian deposits are in 
apparently conformable relation to each other. 
The general effect of the great disseverment alluded to, in determining a 
former outline of the earth, is obvious ; for, whilst the Silurian, Devonian, 
and Carboniferous rocks were at that period so heaved up as to constitute 
portions of mountain-chains, the strata which we are now considering have 
been for the most part spread out in lesser elevations, constituting coun- 
tries with a lower level. Yet, notwithstanding these physical changes, 
the animals and plants of the Permian era, though chiefly of new spe- 
cies, are gcnerically connected with those of the preceding or Carboni- 
