401 
SILURIA. 
[Chap. XVI. 
The reader will see that the Lower Carboniferous rocks (c), consisting of 
the ' Kiesel- ' and ! Posidonomyen-Schiefer,' which in their true positions 
are overlying, here dip under the Upper or calcareous Devonian group, b ; 
whilst the last have been carried under still older members of that series 
(a), or the slaty ' Grauwacke' of this region. Nay, more, he perceives that 
igneous rocks (porphyries, greenstones, &c), formed in part successively 
on the bottom of the same seas in which the Devonian strata (6) were 
accumulated, have also been overthrown en masse with all the other rocks. 
It follows, therefore, that the regular order in which these formations are 
traceable along so wide an adjacent region is here completely deranged, 
and that all the rocks are inverted, the older being incumbent on the 
younger ! Now, this very same phenomenon of the overturning of huge 
masses of the solid crust of the earth has not had its limit in the Rhenish 
Provinces, but has extended into Belgium, where the same strata, as 
described by M. Dumont, are affected along a band having precisely the 
same strike as those great folds in Westphalia and the Eifel*. They are 
therefore to be regarded as great parallel wave-like undulations, similar 
to those of the United States which have been theoretically explained by 
the Professors Sogers. 
In looking back to p. 145, we see indeed that, in Cornwall, this great 
European inversion has proceeded much further to the west, and that 
masses of an antiquity unknown in the Rhenish Provinces and Belgium 
(i. e. the Lower Silurian) there overlie Devonian strata. In that example, 
both the rocks being fossiliferous, no doubt as to the intensity of the 
overthrow can exist. 
It may also be remarked that in one district of Thuringia certain Plant- 
beds which belong to the Lower Carboniferous division plunge under Upper 
Devonian beds charged with Cypridinae and Clymeniae, and that near Ober- 
Steinach, in Meiningen, these Devonian strata are likewise apparently 
surmounted by true Lower Silurian ! 
If a young geologist had detected for the first time such abnormal 
relations in a country like the Eifel, where, besides igneous eruptions of 
remote periods similar to those in the last diagram, the strata have been 
pierced by volcanos which have certainly been in activity under the atmo- 
sphere, he might suppose that the latter, with their craters and coulees, 
must have been associated with some influence analogous to that which 
produced the inversions ; but examination dispels such an hypothesis ; for 
we see that these subaerial volcanos, with their scoriae, pumice, lava, and 
ashes, are nothing more than superficial pustules, which, in bursting forth, 
and spending their energies, produced no sort of alteration in the position 
or nature of the rock-masses. They merely vomited their contents into 
depressions already prepared to receive them, thus showing us that when 
they appeared the present system of hills and valleys had been completed. 
* See the very remarkable geological map of all the volcanic tracts in the Rhenish Provinces, by 
C. von Oeynhausen. 
