154 R. WM. Deeley—Glacial Deposits in the Midlands, ete. 
and yet they are separated from each other by the whole of the 
Middle Pleistocene series. 
I do not mean to affirm that on this account the classification 
adopted by Mr. Jukes-Browne is incorrect, but it is possible that 
some of the brown and purple clays he describes belong to the 
Older and not to the Newer Pleistocene series. Such deposits would 
be difficult to recognize on the east side of the Chalk Wolds, as they 
would contain chalk and flint; but on the west the comparative 
scarcity or even total absence of these rocks should render their 
detection tolerably easy. In the Trent Basin, south and west of 
Newark, there are no signs of a submergence having occurred in 
Newer Pleistocene times. With the close of the Middle Pleistocene 
epoch marine conditions came to an end, and rivers commenced to 
re-excavate their valleys through the masses of Boulder Clay and 
.sand which had been formed in them. Subaerial erosion also seems 
to have been active in Lincolnshire at the same time, for there 
the Newer Pleistocene Hessle and Purple Boulder Clays are found 
at low levels in valleys excavated subsequently to the formation 
of the Chalky Boulder Clay. This would make the Later Pennine 
Boulder Clay of the Midland Counties the equivalent of the 
Hessle and Purple Clays. In the Trent Basin, as I have remarked, 
the Later Pennine Boulder Clay shows no signs of aqueous action, 
whereas the equivalent low-level deposits in Lincolnshire seem to 
be of marine origin. If we admit the possibility of a Newer Pleisto- 
cene submergence of about 400 feet, such as Mr. Jukes-Browne 
requires, great difficulties present themselves; indeed, it would be 
necessary to assume great but local earth-movements without we 
imagine the whole of Central England to have been occupied by an 
ice-sheet, which displaced the water. The severity of the glacial 
conditions which really obtained in Newer Pleistocene times is as 
yet scarcely realized, yet at this age the cold was sufficiently severe 
to permanently freeze the ground in the South of England, and 
bring down great glaciers from the Cambrian and Cumbrian Moun- 
tains, which, spreading over Lancashire and Cheshire, eventually 
passed over the watershed into the Trent Basin. I am aware that 
this is disputed, many geologists regarding the striz as being due 
to large icebergs grating along the bottom of a sea about 1200 feet 
deep; glaciers being with them ata discount. Now an iceberg is 
merely a fragment of a glacier, and therefore the larger the iceberg 
the larger the glacier. Consequently I prefer to make my glaciers 
larger than my icebergs, not vice versa. 
During the Middle Pleistocene epoch the ice-flow seems to have 
passed from the north-east over the submerged Chalk Wolds, giving 
rise to the intensely Chalky Boulder-clay. Ata still later stage, in 
Newer Pleistocene times, the ice came from the Pennine Hills or 
further west, and passing down the Trent Valley, pressed against 
the escarpment of the Middle Oolite. Through the gaps of the 
Humber and Witham Valleys the subglacial streams poured their 
sediment into the sea forming the Purple Clays. At one time it 
is probable that the ice actually passed out through the Witham and 
