1870. ] DE RANCE—GLACIAL PHENOMENA. 653 
rather less than 20 fathoms. The coast-line, especially near the 
base of the Cumberland mountains, appears to have been surrounded 
by an ice-foot, which in winter not only caught up the beach 
formed in summer and before its formation, scratching the pebbles in 
every direction as the ice was lifted by the tide, but received on its 
surface vast quantities of lake-district pebbles, and boulders, brought 
down from the interior by land-ice, which, at the breaking up of the 
iceefoot, were spread in confused heap-like masses over the Lancashire 
and Cheshire lowlands, forming the marine Lower Boulder-clay. 
5. Middle Drift.—That at the close of the period of deposition 
of the Lower Boulder-clay, the climate ameliorated, the subsidence 
of the land still continuing, the influx of muddy sediment ceasing, 
owing to the: cessation of glaciers grinding the rocks on the land, 
and that of sand commencing, owing to the pulverizing of pebbles 
by the action of breakers on the coast-lines of the Middle-drift sea. 
6. That the sand and shingle of the Middle Drift, though found at 
all elevations from 40 to 100 feet between Blackpool and Preston, 
to 1200 feet on the Buxton Road near Macclesfield, was everywhere 
deposited in comparatively shallow water of the same depth, being 
deposited round the ever-sinking coast-lines, on higher and higher 
ground, in the form of sand-banks, whose crests mark the level of 
the mean high water of the immediate period of their deposition,— 
the sinking of the land causing the present elevation of these crests 
to gradually rise from west to east, or from the sea to the Penine 
chain, and everywhere (in West Lancashire) to show a marked uni- 
formity of level in a north and south direction. In the Manchester 
district, owing to the curving round of the high hills of the Penine 
chain, the Glacial sea extended further east'than in West Lancashire, 
though it does not appear ever to have passed over the ridge dividing 
it from the Yorkshire area, the eastern edge of which ridge is shown 
in fig. 1 of Mr. 8. V. Wood’s paper on the ‘‘ Boulder-clays of York- 
shire,” in the February number of the Quarterly Journal. 
7. That if the Middle Drift was thrown down in the form of 
sand-banks surrounding a gradually subsiding coast, it follows that 
though the Middle-drift beds at Blackpool, at an elevation of 80 
feet, and the Middle Drift at Macclesfield at 1200 feet, must have 
been formed during one set of conditions, and in the same geologi- 
cal epoch, yet a considerable period of time must have elapsed be- 
tween the formation of the two deposits; or, in other words, the 
Macclesfield beds must be newer than those of Blackpool. 
8. That the extreme lamination and current-bedding in the Middle 
Drift would, without the littoral character of the shells found in it, 
point to shallow-water conditions; but this current-bedding is 
often so intense as to preclude the idea of its being entirely due to 
ordinary tidal streams, and to suggest rather the sudden currents 
which would be caused by the occasional melting of ice altering the 
temperature of the water. That ice was occasionally present in the 
Middle-drift sea is proved by the fact that beds with scratchea 
pebbles are occasionally found in it, both in the Blackpool, Preston, 
and Chorley districts ; and the contorted and folded Middle Drift 
