292 Paleo-Geological and Geographical Maps of the British Islands. 
elevations of about 600 feet.* The “high-level” gravels of Berks, Wilts, Dorset, and 
Oxfordshire are also probably referable to this division of the drift series. Repre- 
sentative beds are also present in the east of England, interposed between 
two boulder clays. In the west of Scotland I have found similar beds of gravel and 
sand high up amongst the hills of Cantyre, and at less. elevations in the neighbour- 
hood of Glasgow. Out of these gravel beds the more recent Eskers or Kames 
appear to have been constructed. The south of England was probably only very 
slightly submerged at this stage. 
Such then is a general account of the distribution of these interglacial beds. The 
elevation at which the gravels are found is assumed as an index to the measure 
of submergence of the land, as they were certainly formed 7m situ, amongst the 
mountains. This submergence probably reached its maximum of 1,300 or 1,400 
feet about the centre of the British Isles, and was less in the south, and perhaps 
north, of Scotland. At the time the shelly gravels were deposited the British Isles 
became an archipelago in miniature, and in the httle map, plate XXXV.,, fig. 1, 
I have endeavoured to represent their condition during the epoch of greatest 
submergence.t+ 
Puate XXXYV. Fic. 2. 
The Epoch of the Upper Boulder Clay. 
The epoch of greatest submergence, represented in Plate XXXV., Fig. 1, when » 
marine gravels were deposited on mountain slopes of the British Isles at elevations 
as high as 1,360 feet, and when glacial conditions disappeared, except perhaps 
amongst the islets formed of the summits of the Scottish Highlands, was succeeded 
by a second epoch of glacial conditions; not, however, as severe as the first, and 
one which took place when the lands were partially submerged. After the pause 
accompanying the deep submergence above referred to, the land began to rise, and 
considerable tracts of mountainous and hilly ground, previously overflowed by the 
sea, reappeared, and were converted into dry land. This uprising was accompanied 
by a return of cold, so that small snowfields giving birth to smaller glaciers began 
to accumulate on the higher elevations ; and as the glaciers in some cases entered 
the sea, small bergs and rafts of ice dotted the surface of the water, and carried 
their freights of boulders, stones, clay and sand in the direction towards which they 
were impelled by the winds and currents of the period, and as they melted dropped 
their loads over the submerged tracts. At the same time, owing to the melting of 
the snow or ice, numerous streams of red, muddy, glacier water entered the sea, 
which must have been thus discoloured over the central and northern portions of 
* Quart. Journ. Geol. Soc., vol. xi., p. 477. Dr. J. Geikie places the submergence in Scotland at not 
less than 526 feet, or much more, bid. pp- 163 and 329, Lyell suggests 2,000 feet for Scotland. 
“ Antiquity of Man,” p. 324. 
{ This may be compared with that of Lyell. did. p. 325. 
