30 Reviews—Daglish and Forster on the Permian Rocks. 
an upper stratum which is yellow, incoherent, false-bedded, and of 
very irregular thickness; and, occasionally, a lower stratum, which 
is red, slightly micaceous, less false-bedded, containing the remains 
of Coal-plants, and, when present, appearing to pass upwards into 
the yellow sandstone. Either singly or combined, these sandstones 
are found to follow the range and dip of the limestone, and thus to 
rest on much lower beds of the Coal-measures in the south of Dur- 
ham than they do in the north. Hence it is—on the doctrine of 
conformability—that the majority of geologists class this sandstone 
as Permian. On the other hand, all the fossils that have been 
discovered in it are referable to Carboniferous species; and for 
this reason it has been placed by other geologists with the Coal- 
measures. 
Messrs. Daglish and Forster admit both the unconformability of 
this deposit, and its containing Coal-measure plants ; but, so far as 
concerns the red sandstone, they are of the opinion, for several 
reasons, that it does not exist as an independent bed at all; but 
is merely the reddened edges of the Coal-measure rocks themselves ; 
the discoloration, they explain, being due to the oxidation of the 
iron originally contained in the sandstone, by a lengthened exposure 
to atmospheric action. Considerable ingenuity is undoubtedly shown 
in this suggestion, though we cannot see how it meets the case in 
point. Colour is only one element in the character of rocks; and, 
before so novel a view could be accepted, the authors ought to show 
that the general structure of the Red Sandstone agrees with the 
notion of its being merely the red edges of successively out- 
cropping Coal-measure strata. Moreover, atmospheric action— 
powerful though it undoubtedly is—is superficial. It acts on the 
surface, rather than on the interior of rock-masses ; and we most 
certainly dispute that it would ever discolour a rock for a depth of 
fifty feet, let it have been exposed to its influence for what length 
of time it might; and fifty feet is not one-twentieth part of the 
thickness which equivalent red deposits attain in other regions. 
For our part, we feel disposed to admit both the geological uncon- 
formability and the paleontological agreement of this ‘ Lower Red 
Sandstone ’ with the Coal-measures: but instead of attempting to dis- 
pute the existence of any part of the deposit, we think the facts of 
the case simply prove that the Carboniferous flora continued to exist 
after great physical disturbances in the British area;—and, per- 
haps, after all the strata we now call Carboniferous were deposited. 
Hitherto it has seemed most convenient to class this deposit as 
Permian; but there is much to be said in favour of each classifi- 
cation. 
The Magnesian Limestone.—This deposit was first described by 
Professor Sedgwick, whose able memoir is still the text-book for its 
lithology. Professor W. King and Mr. R. Howse followed up the 
investigations of Sedgwick; and in 1850 the former, in the Introduc- 
yived the establishment of the latter as an independent and very distinct formation 
—the ‘ New Red Sandstone’ proper.—Ep. 
