The geology of the neighbourhoods of Flint, Mold, and Ruthin ...

1* CARBONIFEROUS BOCKS.
Shale, .-penetrated only blue clay, the result of the grin;ling-up of
the latter rock in the fault.
. The next section occurs in the stre»n>bed, 450 yards north of
Llanbedr Hall. The New: Red Sandstone runs to within about
yards of the Silurian rocks, the intervening space being
20 .
occupied, by a purplish clay apparently containing fragments of
Wenlock Shale, and perhaps all fault-stuff. The Silurian rocks
are much shattere 1, and have a purplish tinge. The two are seen
again, in close juxtaposition 120 yards north -northreast of the-
Hall, where the Wenlock Shale shows no staining, and the Trias
possesses its usual character of a soft non-conglomeratic sand. .-i.
Immediately to the south of the Hall the limestone suddenly
reappears, in the brook and in a quarry at Oae-glas. The brook;
enters a subterranean course at the fault between the limestone
ancl the Wenlock Shale, and issues at the foot of a little limestonecfift,
in a mass of red and purple clay containing fragments , of
limestone and New Red Sandstone jumbled together, and np.
doubt a fauh-stuff. The rest of the stream-bed lies in Triasi
The quarry shows in part a thin-beddecl- sandy limestone, with
yellow and greenish, shales, dipping to the south-west at 3p°^
These strata seem to belong to the lower limestones of Flintshire,
in which case the fault on the west of the limestone must form
the line of greatest ' displacement. Here, as is generally the
case, the limestone occurs merely as a wedge between two parallel
lines of fracture, forming parts of one great line of dislocation.
It is not seen again south of the quarry.
In the next dingle the line of fault is obscured by Drift, and
in the stream running down to Bathafarn the Wenlock Shale
only' is seen. It appears close to the reservoir, and lias been
tunnelled into in search of coal. The Carboniferous (if any) and
Triassic rocks are concealed by red gravelly Drift. From the
absence of any feature to mark the line of fault, it seems likely
that the New Ked Sandstone is in direct contact with the Silurian
rocks along this part of the Vale.
The Carboniferous Rocks reappear in the dingle running down
to Ysgubor. The Wenlock Shale is shattered for a distance of
grey limestone with thin bands of shale^
130 yards from the fault ;
dipping nearly west at 87° to 90°, occupies the dingle for a
distance of 6 yarJs, and is succeeded westwards by thin-bedded
black limestone, dipping in the same direction at 65° to 70°, the
total distance occupied by limestone being 35 yards. Over the
limestone lies deep-red or purple shale breaking into rhornboidal
fragments, and occupying the dingle for about 15 yards. The
Trias, which comes next, eeems from its disturbed condition to be
introduced by a fault; The black limestone seen in this ding'e is
probably the same bed that runs through the
fechan (Quarter-sheet 74 N.E.).
quarries on Graig-
The great Vale of Clwyd Fault may be traced southwards in
the adjoining Quarter-sheet by Sined, Pentre-coch, and along
the east side of Graig-feehan (Y Graig-wyllt on the one-inch map)