94 REPORT—187 4. 
These beds have been thrown into a number of large flexures, minor contortions, 
and crumplings, as represented in many places on the sections. 
Contemporaneous with these beds are a number of felspathic ashes, interbedded 
felstones, and intrusive felspathic and minette dykes; these, for the most part, occur 
along the lines of bedding and are inclined and contorted with them. They are 
mostly to be found in the Portaferry and Downpatrick districts *. 
After these there seems to come the Granite of Slieve Croob, by some thought to 
be of metamorphic origin, and being probably of Paleozoic aget. 
Subsequent to this Granite, or at any rate after the great contorting up of the Silu- 
rian beds, there occur a large number of dykes, melaphyres, dolerites, and diabase, 
penetrating those contorted beds, mostly in vertical dykes, and which are of an age 
anterior to the Mourne Granite. Of these, the chief source seems to have been towards 
the south of the county; and many of the old pipes or vents are still to be found, as 
on Slieve Moughanmore, Leckanmore, and Slieve Martin +. 
The Carboniferous rocks seem to follow next; but the remains of them are only 
to be found in three localities, viz. at Soldier’s Point, at Castle Espie, and at Holy- 
wood. They probably extended over a large portion of the county, but have suffered 
great denudation, and these isolated patches alone remain. Whether the Coal- 
measures did exist over the Lower Limestone here, as most probably they did, we 
have now no trace of them whatever remaining, they have been entirely swept away ; 
and this denudation seems to have been carried on till the Silurian rock was laid 
bare over most of this district. 
Here may be mentioned the occurrence of the Permian beds in two localities, but 
each of very small extent, viz. near Cultra on the shore of Belfast Lough, and iden- 
tified by the presence of such fossils as Bakewellia antiqua, Schizodus Schlotheimi, 
Productus horridus, and Turbo helicinus ; these beds rest directly and unconformably 
upon the Lower Limestone*. 
The other locality is about 23 miles S.K. of Moira, where asmall patch of breccia 
and earthy magnesian limestone occurs, resting directly on Silurian beds*. 
Next seems to occur the Granite of the Mourne Mountains, in its fullest and 
widest sense an eruptive Granite, carrying up the Silurian beds with it, and cutting 
off the older melaphyric dykes at the junction, as is so well seen in many places, 
especially on Sheve Muck f. 
Subsequent to this Granite, there are two distinct sets of igneous rocks penetrating 
it and the Silurian beds adjacent, with their older dykes. These may be classed as 
uartziferous porphyries and felstones (basic), as found on Slieve Meelmore and 
Slieve Bearnagh. And last of all some basalt dykes, which are supposed to be of 
Tertiary age. 
The author then described in detail the several sections, pointing out the relation- 
ships between the different formations and the different igneous dykes penetrating 
them. 
Referring more minutely to the Scrabo-Hill section, as having a special and more 
local interest, on account of their recent search for coal in that neighbourhood, he 
described the upward passage from the Silurian beds near Killinchy to the Carboni- 
ferous or Lower Limestone and Limestone Shale at Castle Espie, where the lime- 
stone is largely worked and burned in a Hoffman’s laln, at the works of Samuel Mur- 
land, Esq., a thickness of 45 feet being attained by the limestone in the quarries. This 
limestone extends for about 1} mile towards Comber, but is covered with a thick 
head of Drift. It dips northward under the New Red Sandstone formation, which 
in this part of the county comes in and forms the flanks of Scrabo Hill, filling up the 
old valley of denudation extending from Strangford Lough to Belfast Lough. The 
section showed the succession of beds through the Bunter Sandstones, Waterstones, 
and Keuper Sandstones, to the cap of dolerite forming the top of the hill, with an 
elevation of 540 feet. This dolerite or hypersthene rock may be associated with 
the basaltic plateau of the co. Antrim, possibly as an outlier, or a separate pipe 
may exist somewhere to the westward of the summit. 
This trap penetrates the New Red Sandstone beds in horizontal sheets and in 
* Detailed accounts to be found in the memoirs of the Geological Survey of Ireland. 
+ Vide “ Granitic, Plutonic, and Volcanic Rocks of the Mourne Mountains and Slieve 
Croob,’”’ Report Brit. Assoc. 1871, Trans. Sect. p. 101. 
