574 C. CALLAWAY ON THE ARCHAAN AND 
slightest reason for separating it from the Orthis-bearing grit and 
conglomerate which occurs within 200 or 300 yards, and with which 
it is connected by almost continuous outcrops. At its base, the 
Llanfihangel conglomerate rests upon a small inlier of granitoidite. 
The dip here also is towards the east. We may, then, safely con- 
clude that the rocks in this line of section are arranged synclinally. 
On the western side of the basin, the conglomerate covers a much 
larger surface than in the eastern outcrops; but, owimg to the 
obscurity of the bedding and the want of continuity in some parts 
of the section, I could not ascertain whether this was due to 
faulting or folding. | 
Section (2) south of the Holyhead Road.—About Llechylched and 
Bryn-gwyrain the rock is a grey felspathic grit (no. 132, p. 587). 
At the stream near “‘ Factory,” the green conglomerate comes in. 
It is of the same type as in the last section. The dip, as seen south- 
south-west of Cymunod, is clearly to the north-west at 60°. This 
rock is overlain at Tyn-lon by black shale with bands of greenish- 
erey grit, contorted, but striking west-south-west and south-west. 
At Allwyn-goch, the dip of these strata is north-north-west at 80°. 
They are here overlain by green conglomerate, whether a repe- 
tition by folding or a higher band, I could not ascertain; but the 
former seems the more probable. The main points to be noted in 
this section are that the green conglomerate is overlain by black 
shale with grit bands; that the dip rises nearly to the vertical 
towards the contact with the Archzean ; and that the strike is rather 
more to the west than the direction of the Paleozoic zone, which, as 
stated, is south-south-west. 
Section (3) north of the Holyhead AKoad.—This is similar to the 
last, save that the ground on the strike of the green conglomerate is 
covered, so that we can only infer the presence of that band. The 
strike of the black shales varies between west-south-west and 
south-west. 
Section (4) from Ty-hen to the Archean west of Treiorwerth.—This 
line runs obliquely across the zone from south-east to north-west. 
At the bottom of the slope east of Ty-hen, granitoidite is exposed, 
and a few yards to the west is a quarry of the Orthis-grit. In the 
road beyond we pass through a considerable thickness of grit, which, 
towards the north-west, approaches in its composition the grit of the 
green conglomerate series. Overlying this, though we must follow 
the strike to the north to find exposures, is the Treiorwerth or 
Llanfihangel conglomerate. Near a cottage on the main road, 
south-west of Treiorwerth, the grit bands of the black shale occur 
in place, striking to the south-west. <A little further to the west, 
the shales, without grit, are vertical, and in the quarry the dip 
gradually falls to 80°, east-south-east. These beds may berfollowed 
on the strike to the Cwaen locality. 
This section is similar to the last two; but higher beds come in, 
and the dip of these is reversed, as if we had reached the axis of a 
syncline. 
Section (5) from Llechyn-farwy to Cwaen-hen (fig. 5).—Leaying 
