36 A SUBMERGED AND GLACIATED ROCK-VALLEY. _ [ Feb. 1902, 
and cast-iron cylinders were sunk. Therock was not met with until 
a depth varying between 34 and 42 feet below summer water-level 
was reached, or as much as 19 feet below the glaciated surface exposed 
on the northern bank, and it was found then to be sloping towards 
the south at an angle varying from 28° to 18° with a vertical line, 
so that to get a full bearing for cylinders 6 feet in diameter it was. © 
necessary to cut away the rock to a depth of 45 to 56 feet below 
summer water-level, at which depth the rock was still sloping down- 
ward at the same precipitous angle. The face of the rock presented 
an even surface, but the conditions under which it had to be cut away 
did not admit of proofs of glaciation being observed. Scratched stones. 
and pebbles were, however, met with in the clay near the rock. 
About 60 feet farther to the south the silty clay (beneath 16 feet 
of gravel) was penetrated to more than 30 feet below summer 
water-level without reaching the rock. 
The low summer water-level in the river is 48 feet above Ordnance 
datum, so that the glaciated surface which was exposed on the 
northern bank is only 25 feet above that level, and 60 feet farther 
south the rock is sloping down at a precipitous angle at 8 feet below 
mean sea-level, at a distance of 18 miles from the mouth of the river. 
There is here, as in the instances given in the paper above referred 
to, evideice of a very considerable elevation of the Jand during the- 
Glacial Period, with a corresponding greater distance to the sea. 
It was my intention to have exposed to view in the new 
bridge a well striated block of gritstone from the foundation, but 
the glaciated surface began to flake off, and so the block was sent to 
Carmarthen for preservation. Some smaller glaciated and scratched 
stones and pebbles have also been preserved. 
Discussion. 
Prof. Boyp Dawkins pointed out that the Author’s observations,. 
as to the pre-Glacial valleys on the Welsh seaboard having been 
excavated when the land stood at a higher level than it does 
now, were amply confirmed by the examination of the whole of the 
area reaching from Wales to Cumberland. In this area all the 
lower portions of the valleys are filled with Boulder-drift. In some 
cases—as, for example, in the Lancashire and Cheshire plain—they 
have been completely filled up. The observations made for the 
purposes of the Manchester Ship Canal prove that the rock-valley 
of the pre-Glacial Mersey exists at a depth of about 160 feet below 
Ordnance datum to the north-west of Runcorn, and the barrier of 
Red Sandstone reaching across from Liverpool to Birkenhead proves 
that the outlet seaward was not in that direction: it was in 
the Drift-covered region to the north of Liverpool. When these 
valleys were being cut by the pre-Glacial rivers, the 100-fathom 
line was probably the Atlantic seaboard. 
The AvrHor, in connexion with Prof. Boyd Dawkins’s remarks, 
called attention to the specimens of pebbles exhibited, which were 
perfectly rounded before they were scratched. 
