+-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
| | | | Brittany and | | |
| Stages. | Ardennes. | Rhineland. | Normandy. | Bohemia. | Harz. |
/ +-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
| | | Limestone of | Cypridina slates. | Slates of | | Cypridina |
U | | | Etroeungt. | Pön sandstone (Sauerland). | Rostellec. | | slates. |
P | | Famennien | Psammites of | Crumbly limestone (Kramen- | | | Clymenia |
P | | (Clymenia | Condroz (sandy | zelkalk) with Clymenia. | | | limestone and |
E | | beds). | series). | Neheim slates in Sauerland, | | | limestone of |
R | | | Slates of Famenne | and diabases, tuffs, &c., | | | Altenau. |
| | | (shaly series). | in Dillmulde, &c. | | | |
D / +-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
E \ | | Slates of | Adorf limestone of Waldeck | Limestone of | | Iberg limestone |
V | | | Matagne. | and shales with Goniatites | Cop-Choux | | and Winterberg |
O | | Frasnien | Limestones, marls | (Eifel and Aix) = | and green | | limestone; |
N | |(Intumesce- | and shale of | Budesheimer shales. | slates of | | also Adorf |
I | | cens beds). | Frasne, and | Marls, limestone and dolomite| Travuliors. | | limestone and |
A | | | red marble of | with Rhynchonella cuboides | | | shales |
N | | | Flanders. | (Flinz in part). | | | (Budesheim). |
. | | | | Iberg limestone of Dillmulde.| | | |
\ +-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
/ | | Limestone of | Stringocephalus limestone, |Limestones | H_{2} (of | Stringocephalus |
M | | | Givet. | ironstone of Brilon and | of Chalonnes,| Barrande) dark | shales with |
I | | Givérien | | Lahnmulde. | Montjean and | plant-bearing | Flaser and |
D | |(Stringocep- | | Upper Lenne shales, crinoidal| l'Ecochère. | shales. | Knollenkalk. |
D | | halus beds).| | limestone of Eifel, red | | | Wissenbach |
L | | | | sandstones of Aix. | | | slates. |
E | | | | Tuffs and diabases of Brilon | | H_{1}. | |
| | | | and Lahnmulde. | | | |
D / | | | Red conglomerate of Aix. | | | |
E \ +-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
V | | | Calceola slates | Calceola beds, Wissenbach | Slates of | G_{3} Cephalo- | Calceola beds. |
O | | | and limestones | slates, Lower Lenne beds, | Porsguen, | pod limestone. | Nereite slates, |
N | | Eifélien | of Couvin. | Güntroder limestone and | greywacke | G_{2} Tentacu- | slates of |
I | | (Calceola | Greywacke with | clay slate of Lahnmulde, | of Fret. | lite limestone.| Wieda and |
A | | beds). | Spirifer | Dillmulde, Wildungen, | | G_{3} Knollen- | limestones of |
N | | | cultrijugatus. | Griefenstein limestone, | | kalk and | Hasselfeld. |
. | | | | Ballersbach limestone. | | mottled Mnenian| |
\ | | | | | limestone. | |
+-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
/ | Coblentzien |Greywacke of | Upper Coblentz slates. | Limestones | | Haupt quartzite |
L | | | Hierges. | Red sandstone of Eifel, | of Erbray, | | (of Lossen) = |
O | | |Shales and conglom-| Coblentz quartzite, lower | Brulon, Viré| | Rammelsberg |
W | | | erate of Burnot | Coblentz slates. | and Néhou, | | slates, Schal- |
E | | | with quartzite, | Hunsrück and Siegener | greywacke | | lker slates = |
R | | | of Bierlé and | greywacke and slates. | of Faou, | | Kahleberg |
| | | red slates of | Taunus quartzite and | sandstone | | sandstone. |
D | | | Vireux, greywacke | greywacke. | of Gahard. | F-{2} of | Hercynian slates|
E / | | of Montigny, | | | Barrande. | and lime- |
V \ | | sandstone of Anor.| | | White Konjeprus | stones. |
O | +-------------+-------------------+------------------------------+--------------+ Limestone with | |
N | | Gédinnien |Slates of St Hubert| Slates of Gédinne. | Slates and | Hercynian | |
I | | | and Fooz, slates | | quartzites | fauna. | |
A | | | of Mondrepuits, | | of Plou- | | |
N | | | arkose of Weis- | | gastel. | | |
. | | | mes, conglomerate | | | | |
| | | of Fèpin. | | | | |
\ +-------------+-------------------+------------------------------+--------------+-----------------+-----------------+
The chief interest of the Russian rocks of this age lies in the fact,
first signalized by Murchison and his associates, that they unite
within themselves the characters of the Devonian and the Old Red
Sandstone types. In some districts they consist largely of limestones,
in others of red sandstones and marls. In the former they present
molluscs and other marine organisms of known Devonian species; in the
latter they afford remains of fishes, some of which are specifically
identical with those of the Old Red Sandstone of Scotland. The
distribution of these two palaeontological types in Russia is traced
by Murchison to the lithological characters of the rocks, and
consequent original diversities of physical conditions, rather than to
differences of age. Indeed cases occur where in the same band of rock
Devonian shells and Old Red Sandstone fishes lie commingled. In the
belt of the formation which extends southwards from Archangel and the
White Sea, the strata consist of sands and marls, and contain only
fish remains. Traced through the Baltic provinces, they are found to
pass into red and green marls, clays, thin limestones and sandstones,
with beds of gypsum. In some of the calcareous bands such fossils
occur as _Orthis striatula_, _Spiriferina prisca_, _Leptaena
productoides_, _Spirifer calcaratus_, _Spirorbis omphaloides_ and
_Orthoceras subfusiforme_. In the higher beds _Holoptychius_ and other
well-known fishes of the Old Red Sandstone occur. Followed still
farther to the south, as far as the watershed between Orel and
Voronezh, the Devonian rocks lose their red colour and sandy
character, and become thin-bedded yellow limestones, and dolomites
with soft green and blue marls. Traces of salt deposits are indicated
by occasional saline springs. It is evident that the geographical
conditions of the Russian area during the Devonian period must have
closely resembled those of the Rhine basin and central England during
the Triassic period. The Russian Devonian rocks have been classified
in Table II. There is an unquestionable passage of the uppermost
Devonian rocks of Russia into the base of the Carboniferous system.