Chap. XVII.l 
SILURIAN ROCKS OF SPAIN. 
417 
Silurian age, on account of the existence of very imperfect Orthoceratites and 
Corals *. Judging, however, from the mineral structure of the deposits and the 
nature of the intruding greenstones, viz. the abundance of limestone, and the 
absence of granite, so common in the Silurian range of the Sierra Morena, M. de 
Verneuil is disposed to think that these metamorphosed rocks, or at least the 
upper calciferous part of the mass, may be of Triassic age. It is well known 
that these rocks are the sites of some of the richest mines of argentiferous 
galena, particularly near Carthagena, in the Sierra Almagrera, as well as in the 
Sierra di Gador and at the foot of the Sierra Nevada. 
The fossils found in the Sierra Morena and the Toledo Mountains occur usually 
in black shivery schist. The most prevalent is perhaps the Calymene Tristani ; 
but recently many other of the well-known French forms of Trilobites^jn all 
about twenty species, have been detectedf, including Illsenus Lusitanicus ? or 
II. Salteri, Asaphus nobilis, Calymene Tristani, C. Arago, Phacops socialis, Ph. 
Dujardini, Dalmania socialis, and D. Phillipsi, Barr. ; Trinucleus Goldfussi, 
Barr. ; Homalonotus (Plesiocoma) rarus, Placoparia Tournemini, Orthoceras 
duplex, Bellerophon bilobatus, Redonia Deshayesiania, &c. ; also occasionally 
Graptolites have been discovered, of species well known in Brittany, Normandy, 
Bohemia, and Saxony. 
Now, whilst most of these fossils are also found, as has been stated, in the 
slaty schists of Angers and Vitre, in France, which the French geologists have 
mapped as Lower Silurian, several are identical with Bohemian species pub- 
lished as of the same age by Barrande. It is also well worthy of notice, since 
the fossils generally resemble so much those of Central Europe, that the very 
common British species Bellerophon bilobatus, and the remarkable Cephalopod 
Orthoceras duplex (so characteristic of the Lower- Silurian fauna of Scandinavia 
and the North of Europe), should also be found, though very rarely, as M. de 
Verneuil remarks, in this southern parallel. Some of the Silurian fossils enu- 
merated were first discovered by M. Casiano de Prado, near Molina, in Aragon. 
They have subsequently been traced there by the same geologist, and also along 
the eastern borders of New Castile, where they occur in black Graptolite-schists 
which jut out from beneath the Secondary deposits. These Silurian schists have 
further been followed by the same author in the mountains of Checa, Horea, 
Origuela, and Monterde. 
If any Upper Silurian rocks can be said to exist in Spain, they are, as in 
France, only thin courses of black schist, with spheroidal calcareous concre- 
tions in which Graptolites occur, together with Orthoceras Bohemicum and O. 
styloideum of Barrande, and the British Cardiola interrupta. Such rocks, faintly 
exhibited in parts of the Sierra Morena, are also seen on the south flank of the 
Pyrenees, near Ogasa and San Juan de las Abadesas, where they are recognized 
by the presence of Cardiola interrupta and Orthocerata J. It is also supposed that 
a band of siliceous limestone pierced by elvans, or granitic dykes, and which ex- 
tends along the south side of the chain from Gerona, by Hostalrich, to Barcelona, 
may be referred to the same age, Orthocerata having been found in it near the 
* The fossils, alluded to by various authors, t In an examination by Casiano de Prado, 
were to be seen only in very old slabs used as Eusebio Sanchez, and E. de Verneuil. For de- 
floor-stones in some of the houses of Carthagena. tails see the memoir of Casiano de Prado, de 
M. de Verneuil went to that town to examine Verneuil, and Barrande (Bull. Soc. Geol. Fr. ser. 
these slabs, and recognized in them two of the 2. vol. xii. p. 964). 
commonest fossils in Sweden, namely Orthoceras J By MM. de Verneuil and de Loriere. The 
duplex and Asaphus expansus. The red colour of fossils near San Juan de las Abadesas were dis- 
the rock, as well as the fossils, suggested to him covered by M. Amalio Maestre ; they have been 
the idea that these slabs must have been brought quoted by Prof. Leymerie, from near St. Be'at on 
from Scandinavia. If this be the case, in the me- the north side of the Pyrenees, and they exist 
tamorphic rocks of the south coast-range no or- also in Sardinia, 
ganic remains are at present known. 
2e 
