SCIENTIFIC SUMMARY. 
181 
Correlation of the Rocks of the South of Ireland with those of other 
Districts. — Prof. Hull, Director of the 4 Geological Survey of Ireland, read 
an interesting paper before the Geological Society on this subject, on 
March 10th. He referred to a previous paper in which he had discussed the 
geological age of the Glengariff (or Dingle) beds, and arrived at the con- 
clusion that these are Upper Silurian (Upper Ludlow) deposits, greatly 
expanded vertically. These rocks were disturbed, elevated, and denuded, 
and ultimately submerged in such a manner, that the later Old Red Sand- 
stone and Lower Carboniferous strata are found resting transgressively upon 
them. In comparing these Irish rocks with those of North Devon, Prof. 
Hull first showed that the true division between the Old Red Sandstone 
and Carboniferous series must be taken at the top of the 1 Kiltorcan Beds ’ 
with the freshwater bivalve Anodonta Jukesii. He held that the Coomhola 
grits and Carboniferous slate series of the south of Ireland are represented 
in Devonshire by the Barnstaple, Pilton, and Marwood beds, thus relegating 
these divisions of the Devonshire geologists to the Carboniferous. This 
conclusion is borne out by palaeontological evidence. 
The Upcot Flags and Pick well Down Sandstone are to be regarded as 
the representatives of the Kiltorcan beds and Old Red Sandstone and 
Conglomerate of the south of Ireland ; but here the correlation of the forma- 
tions of the two districts ends, for the Martinhoe, Ilfracombe, Hangman, 
and Lynton beds have no representatives in the latter locality. These 
groups, the Lower and Middle Devonian marine deposits, were deposited 
during the upheaval of the Irish Upper Silurians. 
The Foreland Grits, which lie at the base of the whole Devonian series in 
Devonshire being identified by him with the uppermost Silurian, or 
1 passage-beds ’ of Murchison, the author inferred that the great gap 
existing in Ireland between the Glengariff beds and the succeeding Old 
Red and Carboniferous series, was filled up in Devonshire by the beds 
lying between the Pickwell Down Sandstone and the Foreland Grits. 
Accepting Prof. Geikie’s suggestion, that the Scotch ( Lower Old Red ’ 
is the representative of the Irish Glengariff beds, Prof. Hull concluded 
that this ‘ Lower Old Red ’ is really the lacustrine equivalent in time of 
the marine uppermost Silurian strata (a view which is supported by fossil 
evidence); while the 1 Upper Old Red ’ of Scotland is the equivalent of the 
formation bearing the same name in Ireland. Hence it follows that there is 
only one formation properly called i Old Red Sandstone/ and this is the equi- 
valent of the Upper Devonian as restricted to the Pickwell Down 
Sandstone of Devonshire. 
In the district north of the Severn, embracing the region of 1 Siluria/ the 
limestone shale, both by its position and fossils, is shown to be the greatly 
reduced representative of the Barnstaple, Pilton, and Marwood beds ; while 
the Yellow and Red Sandstone and Conglomerate represent the Pickwell 
Down Sandstone, or true Old Red Sandstone. Between this and the Upper 
Ludlow and Passage-beds comes the Cornstone group, to which Mr. 
God win- Austen and Prof. Ramsay have assigned a lacustrine origin. Prof. 
Hull is of opinion that the thickness of this group has been greatly over- 
estimated, and regards 5000 — 6000 feet as the maximum. It was probably 
deposited in an estuary opening seawards towards the south. He accepted 
