1870.] DE RANCE—GLACIAL PHENOMENA. 645 
a tributary of the Mersey, can be proved historically to have been 
once the chief estuary of that river. The southern bank of this 
gorge extends westward to the river Dee, forming an abrupt termi- 
nation to the various ranges of hill and valley, which, coinciding with 
the strike of the component Triassic rocks, run in a series of north 
and south parallels. Most of these valleys are traversed by faults, 
also running in a northerly direction, which, generally throwing hard 
rocks against soft, have caused the initiation of the lines of denu- 
dation of the latter, the soft Keuper marls and upper mottled 
sandstones being denuded away, while the hard beds of the Keuper 
sandstone and Bunter pebble-beds form long lines of escarpment, 
whose steepest sides face the western gales. This, however, as 
has been peinted out by Mr. Hull, is the characteristic feature of 
the Triassic scenery of this part of England. 
With the exception of the crests of a few of the highest hills, the 
whole district 1s covered with glacial deposits—the slopes of the 
hills, equally with the bottoms of the valleys and plains, and even 
the bed of the Mersey itself. 
The low cliffs of Triassic pebble-beds between Eastham and the 
mouth of Bromborough Pool are capped with a thin coating of 
glacial deposits; at one point the Upper Boulder-clay is seen 
resting on some sand, which appears to represent the middle drift, 
about three feet in thickness, resting directly upon the rock, the 
Lower Boulder-clay being absent. On the Lancashire side of the 
river, opposite Eastham, the glacial deposits come down to the level 
of the beach ; it will therefore be seen that the cliff on the south (or 
Cheshire) side of the river, capped with drift, must have been formed 
since the glacial epoch, the river now flowing through an old pre- 
glacial valley since filled up with glacial débris and reexcavated by 
the present river Mersey. 
The Middle-drift sand at Egremont thins out in the direction of 
Liscard, probably terminating against the concealed cliff, or, to speak 
more correctly, the slope of the old valley. No Boulder-drift appears 
to be found in the bed of the Mersey between Egremont and Liver- 
pool ; and the rocks form a low terrace in the lower part of the town ; 
indeed a portion of it is reclaimed from the river itself. In this low 
district, however, certain postglacial deposits occur, hereafter to be 
described. These are about 20 feet thick, and rest directly upon the 
rock. 
I have described the marine Lower Boulder-clay as probably 
formed in water of a maximum depth of about twenty-five fathoms, 
in unequal heaps of deposition, upon a sloping sea-bottom—its 
surface, below the base of the Middle Drift, rising from 5 to 15 feet 
per mile from the sea towards the watershed. On its surface the 
Middle Drift is piled up to a thickness often of 60 and even 70 feet ; 
but at elevations of about 300 feet above the sea it generally rests 
upon rock, above that occasionally on the stiff blue-coloured Lower 
Boulder-clay. It is chiefly composed of sand, with beds of gravel 
dovetailed, so to speak, into the mass. The gravels are much current- 
bedded, apparently by a current moving from the north-west to the 
