40 “TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
of the overlying much later sedimentary rocks of carboniferous 
date, and over these limestones and sandstones we see the 
boulder clays and sands of the great Ice age, bringing us 
within measurable distance of the Historic period. 
Let us, in imagination, while gazing at this panorama, 
dissect our Island, remove it layer by layer, and watch for the 
evidence of colossal changes in nature as we pass back through 
the ages. Remove, in the first place, the houses and fences, 
and other traces of man’s occupancy and mdustry, and then 
wash away from the rocks all the superficial soi! formimg the 
fields and the moorlands, and you have then reduced the surface 
to the condition it was in at the end of the Glacial period, and 
just before the first men made their appearance in this part of 
Britain—and conditions were certainly very different then 
from what they are now. The climate must have been much 
colder. It had recently been arctic, the whole land had been 
buried in glaciers—perhaps, the present condition of Greenland 
or Alaska gives one the best picture of what the scene then was. 
Then again, sometime during the Glacial period, the land 
was much higher than now, and these islands were continuous 
with the Continent of Europe. The Irish Sea, which is now 
of such importance to us, so essential for our welfare and 
prosperity that one can scarcely imagine this land without it, 
did not then exist. It was temporarily filled up to the north, 
south, and east of the Isle of Man, and to the west the deep 
channel which now separates us from Ireland probably existed 
only in the form of a long narrow fresh-water lake or series of 
lakes on the course of a mighty river—perhaps the largest 
river in the British Isles, and far greater than any now existing. 
It started with the Clyde in the north, and running southwards 
along what is now the Firth of Clyde, between Scotland and 
Ireland, received as tributaries the Boyne, and the Liffey, and 
the Mersey, the Dee, and the Ribble, and the imnumerable 
smaller streams from Scotland, Ireland, England and Wales, 
