668 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 22, 
after the formation of the lowland plains, and during a period when 
all the hollows in the much-denuded glacial deposits, both in Lan- 
cashire and in the Isle of Man, were occupied by lakes, which threw 
down the grey silt which I have called the “ Lower Cyclas-clay,” 
and in which the Cervus megaceros is so often found entombed. 
4. It appears probable that glaciers still lingered in the deep 
valley of the Lake-district during the whole of the period occupied 
by the rising of the land, the pause, and its subsequent denudation 
and the connexion of England with the Isle of Man and Wales with 
Ireland. The climate would probably be rather colder than during 
the Hsker-drift period, owing to the greater extent of land cooling 
the air; but the temperature, apart from local causes, was no doubt 
becoming warmer. 
5. At the close of the pause in elevation, before the lake-period, 
when the sea still occupied the low plains of Western Lancashire, 
the Shirdley-Hill sand and the Preesall shingle banks came into 
existence, forming a line of old sand dunes, from which sand was 
blown over the face of the country around Ormskirk, covering up 
the ‘‘lower peat” formed during the period of the pause. Below 
these old sand dunes in the plain, flats of this sand are occasionally 
found, forming the actual sea-bottom of the Shirdley-Hill-sand 
sea. The surface of the sand is worn, more or less, into channels 
by brooks, or small rivers, which no doubt flowed into the lakes, 
which, gradually increasing in size, afterwards covered the whole of 
these low-lying plains, not only between Liverpool and Southport, 
but between Fleetwood and Lancaster, and all the broad estuaries of 
the rivers flowing down from the Cumberland mountains, on the north 
side of Morecambe Bay, with the freshwater “‘ lower Cyclas-clay.” 
6. During the formation of the Cyclas-clay, the entrance, or outlet, 
of all the river- and brook-valleys appears to have been choked and 
obstructed ; for freshwater lacustrine marls almost invariably form 
the base of the alluvium of the valleys in Lancashire and Cheshire. 
On the surface of the clay, on the plains and in the valleys, a forest 
of Scotch firs and oaks came into existence, the former sometimes 
appearing first, and being succeeded by the latter. The trees 
attained an immense size, owing probably to the continental condi- 
tions prevailing. 
7. The country began to subside; drainage became still more 
obstructed ; the growth of peat ensued ; the sea encroached upon the 
land, and gradually worked its way eastwards over the sea-bottom 
of postglacial times—a movement yet in progress, the lowland of 
Western Lancashire and Cheshire being preserved from it only by 
artificial means. In a few places the ground has, partly naturally, 
partly artificially, been reclaimed from the sea, as at the mouth of 
the Alt and Wyre, where it has deposited an Upper Scrobicularia- 
clay on the peat. 
8. Here and there, also, sand has begun to blow during the last 
three or four hundred years, the lines of sand dunes helping to keep 
the sea out. Everywhere the sand, when it first began to form, was 
blown into fresh water. 
