132 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
and slates are surmounted by brownstone. Although no actual 
contact is got of the two rocks, yet a comparison being made of the 
dips, where the two are found nearest to each other, leads to the 
conclusion that they are conformable. Near the south-west angle 
of this region, at Lisbellaw, the fossiliferous Silurian gray grits and 
slates are covered by the brownstone conformably, both having the 
same strike and dip at their junction. The thickness of the brown¬ 
stone is pretty well seen in the middle of the district, in the line of 
country between Clogher and Fintona. Proceeding along the road, 
about a mile from Clogher, it dips north-west, at an average angle 
of about 40°, and this is observed here and there for about two 
miles, and perhaps farther, for the country becomes covered with 
drift. With such dip, two miles of a country would give a thick¬ 
ness of 6780, or say 7000, feet. In the brownstone strata of the 
district, no fossils have been discovered; the examination made 
having been hasty and superficial. There are some beds of red 
limestone in the vicinity of Nine-mile House, on the north-east 
quarter, which are worthy of a closer search. 
In the Tyrone district, along the south-east border, the brown¬ 
stone lies below the Old Red Sandstone unconformably. It dips 
generally to the north-west, while the Old Red Sandstone, of which 
the lower part is red, and the upper part yellow, has a contrary 
dip, being to the south-east. This might be considered the top of 
an anticlinal line, the rock being sandstone at both sides; but it is 
not so. The brownstone, as just stated, is of great thickness, com¬ 
posed of brown grits, very hard, and dipping north-west 40° ; 
while on the south-east of this, the band of sandstone is red near 
base, yellow near the top, all very soft, with some beds of black 
calcareous slate interstratified, and is immediately succeeded by 
carboniferous limestone. The whole band of sandstone being thin, 
and dipping at a low angle, shows that it is not a counterpart of 
the hard, brown, thick-bedded group, just described, and, there¬ 
fore, not an anticlinal line. 
2. The second brownstone district is that of the Curlew Moun¬ 
tains, in the northern part of Roscommon, and extending westwards 
into Mayo—a narrow band of about thirty miles long, by five or 
six miles 'wide. At the east end, near Keadue, green grits and 
slates occur; and at Uggool, at the other end, five miles north-west 
of Ballaghaderreen, gray grits, limestones, and slates occur, abound- 
