24 NOTES ON THE GEOLOGY OF 
the hill, the glacial groovings are clearly seen on the Silurian 
rock. They do not run down the steepest slopes—their general 
direction being E. 10° N. On the limestone behind the stables 
at Cefn the striations are seen running in an E.N.E. direction 
on rock which dips S. 10° E., and have been preserved under 
a small covering of reddish clay, with small rounded fragments 
chiefly of Silurian ; but there are also some pebbles of granite, 
&c., which, with the texture and colour of the mass, lead us to 
refer it to the Clwydian marine drift. 
At the S. end of the Vale on Bryngorlan the striz run easterly, 
some a little N., and some a little S. of E. I know of no striz 
running down the Vale of Clwyd. The ice ignored it altogether, 
and ran across it almost at right-angles to the direction of the 
valley. If we wander beyond the Vale, E. or W. or S., we find 
the same thing. In many places along the coast of N. Wales, the 
striz, instead of running down to the sea, are parallel to the 
coast line. The striz on Caer Drewyn, near Corwen, and near 
Nantbach below it, run a little N. of E. On Hope Mountain 
the glacial grooves run towards the great Cheshire plain, turning 
rather S. of E., while a little W. of Holywell they may be seen 
running in a north-easterly and south-westerly direction, but it 
is not clear whether from N.E. or S.W. 
It may be that the ice from the eastern slopes of the 
Welsh Mountains had to go east on to the Cheshire plain 
because the way north was blocked by ice from the Lake 
District. This would mean that there was one continuous mass 
of ice from Snowdon to Scawfell, and that a great confluent 
stream crushed its way over Chester on to the plain beyond. 
When we get into the high mountains there are obvious traces 
of glaciers (see Ramsay Glaciers of N. Wales.) There small 
glaciers belonging to a later period left their mark in almost 
every valley—but there is no evidence that there ever was 
a glacier travelling down the Vale of Clwyd—so that the 
marks of the great ice that came from Arenig and Snowdon 
were not obliterated by any small glacier of later times, when 
the conditions no longer allowed the Snowdon ice to reach 
so far. 
During the period of extreme glaciation all was covered by 
ice, and we could not have any fauna or flora in our district. 
If few peaks stood above the ice, but little material could 
fall on it, only just enough to act as a rasp on the underlying 
rock, for ice with no stones in it could not do much scratching 
work. The few stones that did get on it would soon be 
swallowed up in the crevasses, and be rolled and polished and 
scratched against one another and the rocks over which the 
glacier passed. So this must have been the time when the 
far transported boulder-clay was formed, with few stones in it, 
but most of those glaciated. 
Of this we cannot expect to find traces in our district. It 
— 
