30 NOTES. ON THE GEOLOGY OF 
The bed /a) exposed in the road cutting is a kind of ancient 
rainwash loam, fine and homogeneous, and much frequented 
by wild bees. 
On the opposite side of the road there is a steep cliff of drift 
generally bare of vegetation nearly down to the mill race. The 
bottom of the cliff for about 50 feet is less well exposed, as the 
talus accumulates near the base, and I do not know whether the 
lowest part should not be referred to the older or Welsh 
Mountain drift. Inthe upper part a few fragments of shell occur 
here and there. The rock is nowhere seen, but it occurs at the 
level of the base of the cliff on the other side of the valley. 
Higher up the valley of the Elwy, the red sand of the 
Clwydian drift is seen in a small section above the cottages 
at the bend of the river below Dolben; and still higher up the 
gorge, at the bend of the river near Dol, there is a very fine 
section in yellowish sand associated with reddish boulder-clay, 
which must all be referred to the Clwydian drift (see fig. 17.) 
It rests on blue boulder-clay, probably the older or Welsh 
Mountain drift. 
Fic. 17. 
Section of River Cliff near Dol, Valley of the Elwy. 
Black peaty silt and clay. 
Reddish boulder-clay. 
Sand. 
. Grey boulder-clay. 
The beds a, 4, and c, have slipped over d, and probably may 
not here occur 7” sz/u quite at the bottom of the valley, but their 
relative position can be made out from an examination of the 
whole section. The peaty bed on top probably belongs to some 
pond in surface of the drift which has slipped with the rest. 
The marine drift of the upper part of this hill was probably 
continuous with that by Bryn-y-pin, and belongs to the 
Clwydian series. 
Down the road between Wern and Pen-y-banc, N. of Pont- 
yrddol, there is a grey gravel and here and there beds of 
sand. It was all, as far I could see, composed of Silurian 
and Cambrian rocks, and seemed to belong to one of the later 
ages of denudation. 
At the east end of the estuary it lies on the flanks of the 
limestone hills about Dyserth, where mining operations have 
proved it to 170 feet in places—Figs. 18-19. 
Fic. 18. 
Diagram Section Talargoch, Dyserth. Oct. 7, 1875. 
a. Mountain Limestone. 
[Millstone Grit is shewn on Survey Map, but I could not verify 
its occurrence in this section. ] 
b. Marine gravel, sand, and clay drift. The details of this part of the 
section are given in Fig. 19. 
c. Lode. 
AD SB 
