TRANSACTIONS OF THE SECTIONS. a3 
appears, then, from this description, that above the Upper Silurian rocks, containing 
true Ludlow fossils, and having a thickness of 3000 or 4000 feet, red rocks set in quite 
conformable to, and graduating into these upper Silurian rocks, and that these red rocks 
have a total thickness of 10,000 or 12,000 feet. So far the facts are in exact accordance 
with those of the typical Silurian district of South Wales, &c., and the Glengariff grits 
and Dingle beds may be placed on a parallel with the Cornstone group of Siluria and 
the Cephalaspis beds of Scotland. Unfortunately this identification has not been con- 
firmed by the discovery of any fragments of Cephalaspis or other fish remains in the 
Dingle district, but it is one that few persons, perhaps, will be inclined to dissent from. 
Unlike Siluria, however, instead of being covered in apparent sonformity by red 
sandstone and conglomerates forming part of an apparently continuous series, the 
Glengariff grits and Dingle beds are totally separated in the Dingle promontory from 
these overlying sandstones and conglomerates by as complete a discordance of position 
as can anywhere be seen, even between the Trias or New Red Sandstone, forming the 
base of the Secondary, and the Carboniferous, Silurian, or other Palzeozoic rocks. It 
certainly seems to the authors impossible to group these two entirely separated and 
discordant things under one name like that of Old Red Sandstone, and advisable to give 
them two separate names. 
If the upper red sandstones and conglomerates which pass conformably upwards 
into the base of the true carboniferous rocks should retain the name of the Old Red 
Sandstone, some other designation should be given to the Glengariff grits and Dingle 
beds. If we call them Devonian, it follows that the terms ‘ Old Red Sandstone” and 
“Devonian” can no longer be considered synonymous; if, on the other hand, we 
keep those names as synonymous, then some other term must be introduced to desig- 
nate the Glengariff grits and Dingle beds of Ireland, and the Cornstone group of 
Siluria and Cephalaspsis beds of Scotland. The Old Red Sandstone, which passes con- 
formably up into the carboniferous rocks, may then be considered as the true base of 
that system, and with it may be classed the red sandstones and conglomerates having 
over them yellow sandstones often containing plants, which underlie the carboniferous 
slates and lower limestone shales of South Ireland, South Wales, and South England, 
the scraps of old red sandstones found here and there under the carboniferous lime- 
stone of North Wales and North England, and also the Upper Old Red or Yellow sand- 
stone of Scotland, containing Holoptychius nobilissimus, Cyclopteris (Sphenopteris) 
Hibernica, &c. 
The Middle Old Red of Scotland, or Cephalaspis beds of Miller, and also the Lower 
Old Red or Pterichthys beds of the same author, can, if the author’s views be correct, 
no longer be considered as Old Red Sandstone at all. What position the true Devonian 
rocks of Devonshire and the Eifel beds of the Rhine will occupy with respect to the 
two groups of red sandstone and conglomerate (the one capping the Silurian, and the 
other forming the base of the carboniferous), is still uncertain, ‘They may be either 
wholly or in part the contemporaries of the one or the other, or they may be inter- 
mediate between the two, deposited perhaps in the long interval which in the Dingle 
district was occupied by the elevation and contortion and great denudation of the 
lower group, and the exposure of the Silurian rocks on which they rested. 
Notes on the Old Red Sandstone of South Wales. 
By J. Beets Jukes, MA., P.RS., MRA. 
_ After examining the work of the Geological Survey of the Dingle district, and seeing 
that the rocks, which by most geologists would be considered to be Old Red Sandstone, 
were there apparently conformable at their base to the top of the Upper Silurian rocks 
containing Ludlow fossils, and conformable at their top to the base of the carbonife- 
rous rocks, while they were themselves separated into two groups by an utter discord- 
ance and wide unconformity in their centre, the author took a very hasty run on 
leave of absence into South Wales, for the purpose of seeing whether anything similar 
could be discovered there, if the country were to be re-examined with that express 
object. The short time at his disposal compelled him to confine his observations to 
three districts:—Ist, the country about Llandeilofawr, and thence to Llandovery; 
2ndly, the Beacons of Brecon; drdly, the valley of the Usk, south of Abergavenny and 
east of Pontypool. 
