122 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
I have in this Table recorded the dips of both rocks, at or near 
the junctions, in seventy-eight localities; and I might easily give 
double the number, were it not that, when I was employed on the 
General Valuation of Ireland in the north, though careful to note 
the dip at every opening of sandstone I met, I omitted in many in¬ 
stances to take the necessary pains to determine the dip of the mica 
slate or clay slate in the vicinity, as that is frequently obscure, 
from the cleavage of the slate, or from being covered with drift. 
This was more especially the case in the county of Tyrone, about 
Plumbridge, and thence along the southern bases of the Bessy Bell 
and Mary Gray mountains, towards Castlederg. 
It will be seen also in the Table that, in those seventy-eight 
localities,— 
The Old Bed Sandstone rests on mica slate . . in 19 
On gray clay slate,.27 
On gray grit, or quartzite, . 3 
On gray grit, interstratified with gray clay slate, . 6 
On green grit,.3 
On green grit, interstratified with gray clay slate, . 2 
On brownstone, or brown hard grit,.7 
On brown micaceous flag, with brown or purple slate, 1 
On yellowish-white stratified quartz rock, ... 2 
On yellowish-white quartz rock, bedding obliterated, 2 
On brown porphyry,.1 
On greenstone,.4 
On granite, .. 1 
cases. 
n 
n 
»» 
« 
51 
51 
35 
13 
11 
5 ? 
51 
15 
This abstract shows, perhaps more clearly than any other evi¬ 
dence I could adduce, that, after the great disturbing forces which 
rolled the earliest stratified rocks into such undulations, as we now 
find in them, followed by a powerful denuding agency, that broke 
up and carried away the tops of many of the anticlinal convolutions 
formed in them, and left the beds thrown up on their edges, the 
conglomerate of the Old Red Sandstone was the first layer, or foun¬ 
dation of a new building—the Carboniferous formation. This 
band was laid down upon those edges of the older rocks, as they 
happened to present themselves, whether slate, grit, quartz, lime- 
