66 REPORT—1857. 
district prevents one getting a good section.. The lines of stratification are also often 
much effaced by joints, cleavage, and weathering of the surface, Under the limestone 
comes the carboniferous slate, consisting of black shale, brown grits, and some cal- 
careous bands, full of fossils, the thickness being about 500 feet. Next comes the 
yellow sandstone of Dr. Griffith, consisting of yellowish grit and shales, varying from | 
500 to 1000 feet in thickness. The former is the thickness at the Slieve-Mish 
mountains near Tralee; the latter that near Bird Island. Here I discovered a thin 
bed full of plants, all branching and some having a cellular structure ; there are some 
leaves that look like those of Cyclopteris Hibernica. 
Below the yellow sandstone comes a considerable thickness of red sandstones and 
slates, amounting at Slieve-mish to about 800 feet; from this they pass downward into 
a conglomerate. A remarkable point about this conglomerate is the manner in which 
it varies both in thickness and character. Its thickness where it is shown on the line 
of section, is about 80 feet, and it consists of large and small rounded pebbles of 
quartz, jasper, and hornstone, in a base of red sand; while about one mile and a half 
further west (on the south side of the anticlinal of the Slieve-mish range, where the 
beds are thrown down by a fault), it is more than 200 feet thick, and consists of large 
angular fragments of gneiss, mica-schist, grey grit, trap ashes, &c., thinning out on 
the northern slope to about 50 feet. 
This conglomerate is the lowest rock seen in this section, but it must not be con- 
founded with that which is now considered as the base of the carboniferous rocks in 
this district, and which is several hundred feet below it, and lies unconformably on 
the Silurians. 
On the Relations of the Rocks at or below the base of the Carboniferous Series 
of Ireland. By Sir Ricuary Grirrith, Bart, LLED., MRA, F.GS. 
The author stated that he had found great difficulty, when preparing the several 
editions of his Geological map of Ireland, in deciding on the class to which certain 
rocks characterized by brown and reddish-brown grits and conglomerates ought to be 
assigned. 
These rocks occur in three districts in the north; viz. one in the neighbourhood of 
Pomeroy and Omagh, in the counties of Fermanagh and Tyrone, one forming the 
Curlew mountains in Sligo and Mayo, one forming the Croaghmoyle mountains and 
neighbourhood in Mayo, and one extensive district in the south occupying large por- 
tions of the counties of Cork and Kervy. 
The author then referred to his paper read at the Cork meeting of the British — 
Association for the Advancement of Science, from which it appeared that he was then 
inclined to connect the conformable brownish-red sandstones and conglomerates with 
the Silurian system. 
The author next referred to his paper read to the Belfast meeting of the Asso- 
ciation on the yellow sandstone of the north shore of Mayo, and to the advice tendered 
to him by Sir H. De la Beche and Mr. Jukes, with reference to the omission on his 
map of the so-called Old Red Sandstone district, as the red rocks appeared to them to 
be all carboniferous, an opinion confirmed by the subsequent discovery of Sigillaria 
and Stigmaria ficoides within the area, as also in similar rocks at MacSwyne’s Bay in 
Donegal, a very large specimen from which locality is preserved in the court-yard of 
the Royai Dublin Society. 
It appears therefore that these supposed Old Red Sandstone rocks of the North are 
undoubtedly carboniferous; but it is yet doubtful to what series the red rocks below 
lying unconformably to them may belong. fj 
The author then mentioned the limits of the true Old Red Sandstone of the South, 
from the east to the west side of the island, reposing on other red and purple rocks, 
which in the Dingle district become distinctly unconformable to them, while the red 
and purple rocks themselves repose conformably on fossiliferous Silurian rocks. ; 
He then described the grounds on which he based his division of yellow sandstone, 
principally from the occurrence of plants subsequently found by Professor Haughto 
Mr. Jukes and others, to extend still lower down into the red rocks; and stated, that 
he considered the plants to be the proof of the yellow sandstone being of carboniferous 
age, he was not prepared to deny the inference that the whole of the fish-beds 
