322 
SILUKIA. 
[Chap. XIII. 
Persistent in its character of contraction and great local expansion, the Roth- 
liegende, which has thinned out at Saalfeld, resumes its importance at Gera, near 
to which place it is to be partially seen, underlying and fairly passing into the 
Weiss-liegende j whilst to the north of that city, the lower red deposit, rising 
out from beneath all the Zechstein series, swells out to a vast thickness, and 
again occupies a broad tract extending far into Saxony on the north and east. 
The memoirs of Dr. Liebe, of Gera *, have fully explained the positions of the 
fossils which occur in such abundance in the environs of Gera, and which can be 
so well studied in the fine collection of M. Dinger of that town f. 
The material point which I seek to establish is, that there, and on the right 
bank of the Elster, the geologist sees a section which leaves no doubt of the pro- 
priety of binding together the different members of the Permian group in the 
manner indicated. 
It is true that on the banks of the Elster, near Gera, the uppermost bed only 
of the Roth-liegende can be observed ; but as this deposit has been pierced to a 
great depth in fruitless searches for coal on the opposite bank of the stream, no 
one can doubt that the true Permian foundation-rock is here developed on a great 
scale. The upper member of the Roth-liegende, which is there visible, presents 
all the unmistakeable characters of the deposit, being made up of fragments, more 
or less angular, of quartz, lydian stone, and particles of the older rocks in a deep- 
red sandy paste, here and there spotted with green. This rock passes gradually, 
and without the smallest appearance of discordance or separation, into a lighter- 
coloured conglomerate of about 10 feet in thickness, composed of broken fragments 
of quartz-rock and greywacke, somewhat ochreous downwards, and becoming 
white, or light-grey, upwards. The latter rock, containing many of the same 
fragments as the lower red mass, has in its upper part a calcareous and highly 
magnesian, instead of a siliceous and argillaceous paste. 
Now this whitish conglomerate, which is truly the upper part only of the 
Roth- and Weiss-liegende, and is conformably overlain by the Kupfer-Schiefer, 
already contains the following fossils, so typical of the Zechstein in various 
countries : viz. Productus Cancrini, de Vern., Lingula Credneri, Gein., Stropha- 
losia Leplayi, de Vern., Avicula, Pecten Mackrothi, von Schaur., Terebratula 
Geinitziana, with the Plants Ulmannia frumentaria and Ul. lycopodioides, Gop- 
pert, &c. 
In this way the basement conglomerate rocks are linked on by these animal 
remains, as well as by chemical constitution J, to the calcareous central strata. 
At the same time it is worthy of consideration that the same species of Mollusks 
were in existence whilst the action which evolved the inferior conglomerates was 
drawing to a close, and that even subsequent to the appearance of such Mollusks 
a remarkable change occurred in the sea-bottom, by which the dark-coloured 
mud, occupied by the remains of peculiar Fishes, and known as the ' Kupfer- 
Schiefer,' was spread out over a wide region. But the calcareous element recur- 
ring, the same Mollusca again flourished, and became still more abundant in the 
overlying Zechstein. 
Difference between the Permian Mocks of Northern and Southern Germany. — 
Although not yet very exactly defined in geological maps along its southern 
* See Zeitschr. Deutsch. Geol. Gesells. vol. vii. Mackrode is also celebrated, 
p. 406 &c. I See Liebe's Notice on the conglomerate Zech- 
t Dr. Liebe and M. Dinger obligingly accom- stein, Zeitscb. Geol. Gesells. ix. p. 407, which ! 
panied Professor Rupert Jones and myself to the shows an increase of magnesia from the Roth- 
examination of the strata here described ; and we liegende into the Weiss-liegende, and a greater 
were much gratified by the inspection of numerous quantity of it in the pebbly Zechstein than in the 
beautiful fossils in the museum of the last-men- overlying Zechstein. 
tioned gentleman. The collection of the Rev. M. 
