remains of those two members of the series which are
known as the “Old Red Sandstone” and the
“Devonian” rocks proper. This discrepancy,
however, is not complete; and, as we have seen, can
be readily explained on the supposition that the one
group of rocks presents us with the shallow water
and littoral deposits of the period, while in the
other we are introduced to the deep-sea accumulations
of the same period. Nor can the problem at issue
be solved by an appeal to the phenomena of the British
area alone, be the testimony of these what it may.
As a matter of fact, there is at present no sufficient
ground for believing that there is any irreconcilable
discordance between the succession of rocks and of
life in Britain during the period which elapsed between
the deposition of the Upper Ludlow and the formation
of the Carboniferous Limestone, and the order of the
same phenomena during the same period in other regions.
Some of the Devonian types of life, as is the case
with all great formations, have descended unchanged
from older types; others pass upwards unchanged to
the succeeding period: but the fauna and flora
of the Devonian period are, as a whole, quite distinct
from those of the preceding Silurian or the succeeding
Carboniferous; and they correspond to an equally distinct
rock-system, which in point of time holds an intermediate
position between the two great groups just mentioned.
As before remarked, this conclusion may be regarded
as sufficiently proved even by the phenomena of the
British area; but it maybe said to be rendered a certainty
by the study of the Devonian deposits of the continent
of Europe—or, still more, by the investigation
of the vast, for the most part uninterrupted and continuous
series of sediments which commenced to be laid down
in North America at the beginning of the Upper Silurian,
and did not cease till, at any rate, the close of
The following list comprises the more important works
and memoirs to which the student of Devonian rocks
and fossils may refer:—
(1) ‘Siluria.’ Sir Roderick
(2) ‘Geology of Russia in Europe.’
Murchison (together with De
Verneuil and Count von
(3) “Classification of the Older Rocks
of Devon and Cornwall”—’Proc.
vol. iii., 1839. Sedgwick and Murchison.
(4) “On the Physical Structure of Devonshire;”
and on the
of the Older Stratified Rocks of Devonshire
Geol. Soc.,’ vol. v., 1840. Sedgwick
(5) “On the Distribution and Classification
of the Older or Palaeozoic
Rocks of North Germany
and Belgium”—’Geol. Trans.,’
vol. vi., 1842.
Sedgwick and Murchison.
(6) ‘Report on the Geology of Cornwall,
Devon, and West Somerset.’
De la Beche.
(7) ‘Memoirs of the Geological Survey