RESEARCHES AMONG THE PALEOZOIC ROCKS OF IRELAND. 131 
inference, that there is no doubling up or repetition of the strata, 
in the fact, that the fossiliferous band at Ferriter’s Cove, composed as 
it is of greenish and gray slaty rocks, with abundance of Catenipora 
esciiaroides , is by its strike in the lower part of this section, and the 
fossiliferous band at Foyleatliurrig, which has neither green nor gray 
slates, nor Catenipora escharoides , but brown slates and grits, and 
other species of fossils, is evidently in? the upper part. Those two 
bands are not the two arms of a convolution; but one band near 
the base, and another near the top of a continuous unbroken section, 
which here is twelve miles from north to south, with an average 
dip of 70°, making a thickness of 59,500 feet, without seeing either 
the bottom or the top of the group. By the fossils alone, without 
reference to the thickness, this group, which consists of alternating 
bands of brownstone, and brown, red, and purple slates, green and 
gray grits, and green and gray slates, is all Silurian, without any 
doubt: and the overlying sandstone, with its band of conglomerate 
for a base, and its unconformable position, is the true Old Red Sand¬ 
stone of the Carboniferous system, which, as was said before, passes 
in parallel beds and conformable succession, upwards into the moun¬ 
tain limestone. 
Besides the Dingle peninsula, there are other brownstone dis¬ 
tricts in Ireland, some of which are intimately associated with strata 
containing Silurian fossils. I shall notice them separately, beginning 
in the north of Ireland, and proceeding southward as they occur 
upon the map. 
1. The first is a region in the counties of Tyrone and Fermanagh, 
stretching in a south-west direction, between Pomeroy and Ennis¬ 
killen. It is forty miles long, and nearly ten broad. It is inter¬ 
sected by many dykes of greenstone, and has numerous bosses of 
brown porphyry. The brownstone of this district consists of the 
following varieties :■—First. A strong brown conglomerate, composed 
chiefly of pebbles of brown quartz rock, hard and semi-transparent 
atLisnanick,on the north-west corner. Second. The chief part is com¬ 
posed of brown grit, near the south-east border. Third. Some softer 
slates and shales, apparently in the upper part, about Fintona and 
Trillick. A remarkable characteristic point in the grit beds here 
and elsewhere is, that they contain angular fragments of brown 
slate, of very fine grain, two to four inches long. 
At the north-east end, near Pomeroy, the Silurian gray grits 
