File:The Quarterly journal of the Geological Society of London (12711701523).jpg

412 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. .Apr. 4,
ous wooded mass, the culminating points of which never exceed 3500
EngUsh feet above the sea, and whose main direction is from N.W.
to S.E. Its length from the environs of Eisenach on the N.W. to
those of Kronach on the S.E. is upwards of sixty miles, and swelling
in width from a narrow apex on the N.W. it attains a maximum
width of about twenty miles in its S.E. portion.
The south-eastern half of this tract is essentially distinct from the
north-western ; the first or wide part being made up of very ancient
sedimentary strata, the second of crystalline rocks chiefly eruptive
and here and there of metamorphic character ; whilst the whole is
surrounded by a girdle of Permian rocks, followed by lower mesozoic
deposits which delineate the dominant direction of the mountains
which they subtend.
Fig. 1 . — Diagram showing the General Succession of the Palaeozoic
Rocks in the ThUringerwald. Horizontal distance about 12 miles.
N.W. S.E.
1. t tx
e, Permian (Rothe-todte-liegende, Zechstein,
and Sandschiefer).
d. Lower Carboniferous.
c. Upper Devonian.
b. Lower Silurian .b*. Courses of limestone).
a. Bottom rocks.
Lower Grauwacke or Cambrian^ and Silurian. — The most ancient
rocks, as seen in the S. Thiiringerwald, consist of greenish talcose
schists, traversed by white quartz veins, and of ferruginous and
purple sandstone, the latter much resembling certain rocks of the
Longmynd in Shropshire. When examined in detail, these rocks
(marked a in the general diagram, fig. 1) exhibit towards the base
quartz rock and dark slaty schist, the latter containing aluminiferous
schist. These form the lowest courses, as seen in several undu-
lations ; the upper and chief part being the greenish slaty rocks above
mentioned, and in which whetstones occur. In these rocks ("griine
grauwacke" of Richter, or " Cambrian" of the British Geological Sur-
vey), which have all been affected by a slaty cleavage, no other organic
remains except Fucoids .Phycodes circinatus) have been found.
These fundamental rocks («), exhibited in masses of great dimen-
sions, and attaining, in the Oberland of Meiningen, elevations of up-
wards of 3000 feet above the sea, are covered conformably by the
deposits which M. Richter termed grey grauwacke, an extensive and
diversified group (6) of slate and sandstone with some courses of alumi-
niferous schist .graue grauwacke, dach-schiefer, griff el-schiefer, &c.),
the whole of which is referable through its fossils to the Lower Silu-
rian rocks. The section, fig. 1, merely represents the general suc-
cession. But from the observations of M. Richter, we believe that
this fossiliferous Lower Silurian consists in its inferior portion of