Chap. XI.] OLD EED SANDSTONE OF SCOTLAND. 251 
Lyell in his ' Manual of Geology/ Since this section was made, great 
additions have been made to our acquaintance with the details of the Old 
Bed series in this part of Scotland. Some years ago, in company with 
Section across the Old Eed op Forfarshire. 
S.W. N.E. 
Whiteness. Sidlaw Hills. Strathmore. 
c b a a a b c d c b a 
a. Clay-slate, b. Grey paving-stone and tilestone, with green and reddish shale, 
containing Pterygotus and Parka decipiens * c. Eed conglomerate, d. Eed sand- 
stone, with Ichthyolites &c. g. Eed shale or marl, unconformable to the lower rocks. 
Mr. Powrie, I saw that the mass marked b is, on the eastern or moun- 
tainous side (where it reposes on the crystalline rocks), a very hard and 
grey gritty conglomerate charged with Parka decipiens f. 
Mr. Powrie has since shown that, after great flexures, the lower strata, 
passing under red sandstones and conglomerates, reappear on the east 
coast, their prominent fossiliferous member being the Arbroath flagstones. 
He has, indeed, communicated two interesting memoirs to the Geological 
Society on this subject J. In the first of these he shows that, east of the 
Grampians, all the old stratified sediments of Forfar which he has ex- 
amined consist of these two divisions only of the Old Eed Sandstone. In 
the second he indicates how their equivalents in Fifeshire are surmounted 
by an Upper Old Eed deposit — the yellow sandstone of Dura Den, so cele- 
brated for its numerous and peculiar Ichthyolites. 
It was indeed very gratifying to find that, since the last edition of 
'Siluria' appeared, both Mr. Powrie and his very skilful coadjutor Mr. 
Page, whose writings on geology are so widely known, had seen fit to 
acknowledge that the lower sandstones and flags of Forfar, with their 
Cephalaspis, Pteraspis, Pterygotus, and Parka decipiens, are, as I had pre- 
viously placed them, inferior to, or older than, the great fish-beds of the 
north, viz. the Caithness Flags. These authors admit, in short, that the 
Lower Old Eed of Eoss, Sutherland, and Caithness, which I described 
forty years ago, and of which I treat in the sequel as the base of that 
series, is the true equivalent of the Arbroath paving-stones and the lowest 
Old Eed of Forfarshire §. 
* My valued friend the late Eev. J ohn Fleming, tacle, and that the round covering bodies are 
D.D., who wrote original papers on the organic carpels or fruits. It is now known as the Parka 
remains of the Old Red Sandstone, first assured decipiens, and is usually regarded as the eggs of 
me that a fruit-like body found in Fifeshire and Crustaceans. See p. 239, and notes, pp. 238, 239. 
in the Arbroath paving-stones of Forfarshire was | See also Page's ' Advanced Text-book of Gre- 
unquestionably a vegetable, and could not be ology.' 
classed as the egg of a Mollusk as suggested by T Quart. Journ. Greol. Soc. vol. xvii. p. 534, and 
Lyell, or as the egg of a Batrachian as more re- vol. xviii. p. 427. 
cently proposed by Mantell. The figure which § Whilst these pages were going through the 
Dr. Fleming gave in the year 1831, Edin. Journal press, I received from the Natural History Society 
of Nat. Science, vol. iii. pi. 2. f. 5, certainly favoured of Montrose photolithographic representations of a 
the opinion that it was an aggregate fruit. Since splendid specimen of Pterygotus Anglicus, found 
then he examined both the upper and under sur- in the Lower Old Eed Sandstone of Carmylie, 
faces, and quite satisfied himself that it is a recep- Forfarshire. Accompanying the Keport of the 
