Paleo-Geological und Geographical Maps of the British Islands. 271 
Pirate XXVII. 
Old Red Sandstone and Lower Carboniferous Periods. 
In order to save the engraving of a separate plate, I have endeavoured to include 
the above sets of strata in one pair of maps, although the Old Red Sandstone is a 
member of the Upper Devonian Series, rather than of the Carboniferous. This is 
proved by the occurrence of Old Red fishes (Coccosteus, Picrichthys, Asterolepis, &c.), 
together with plants (Adiantites Mibernicus), and fresh-water molluses (Anodonta 
Jukesii), in the beds of this formation in Ireland. In many districts, however, the 
Old Red Sandstone appears to be conformable to the overlying Lower Carboniferous 
beds, while unconformable to all strata older than the Middle Devonian beds, and 
as these are only present in the south of England, Belgium, and France, the Old 
Red Sandstone is elsewhere unconformable to the strata on which it reposes. 
The strata included in Plate XXVII., range from the Old Red Sandstone or Con- 
glomerate to the top of the Carboniferous Limestone. At the commencement of the 
deposition of these beds the greater part of the area now described existed as land. 
But as time went on, the British area became depressed, and the sea gradually 
gained on the land; so that, at its close, only the northern and western tracts were 
unsubmerged, together with portions of the border districts of Scotland. ‘The 
Cumberland mountains, and a tract ranging* from North Wales, Shropshire, and 
the centre to the east of England was also unsubmerged. Over the submerged 
areas the Lower Carboniferous strata were deposited ; from the unsubmerged dis- 
tricts they are absent. Throughout South Staffordshire, parts of Salop, Leicester- 
shire, and Warwickshire, the Upper and Middle Carboniferous beds rest directly 
on the Silurian or Cambrian beds.t+ 
Nature of the Old Red Sandstone—The Old Red Sandstone is found over the S. 
of Ireland in the form of a massive conglomerate, forming fine escarpments in the 
Commeragh and Dingle mountains, and passing upwards into finer red sandstones, 
and beds of flagstone and shale. The uppermost beds, called the “Kiltorcan 
beds,” contain fish-remains, a fresh-water mussel (Anadonta Jukesii), and plants. 
They are lucustrine deposits over the area of the south of Ireland, and mark the 
upper limit of the Old Red Sandstone. 
In South Wales, along the northern margin of the coal-basin, the Old Red 
Sandstone forms bold cliffs, rismg from below the Carboniferous limestone and 
shale, and consists of yellow sandstone and conglomerate. In North Devon, it is 
* It is possible that the sea may have spread between North Wales and the Wicklow mountains 
‘during this time. 
{South of Halesowen, the Upper Silurian beds were penetrated by a coal-shaft under the Upper 
‘Coal-measures, and at Dudley, Forest of Wyre, Shrewsbury, &c., the Upper Coal-measures rest on 
Lower Paleozoic beds. 
