MARINE BIOLOGICAL STATION AT PORT ERIN. - 4] 
joined the Severn lower down, and finally opened into the 
North Atlantic, somewhere between Finisterre and the South 
of Ireland. 
The change from that picture to the period immediately 
succeeding the Ice age, when the land sank and the Atlantic 
flowed in and filled up the Irish Sea, and the climate became 
more genial, and forests covered the land, and the fauna and 
flora spread and multiplied, and finally neolithic man made 
his appearance in this island, pursuing the great Irish Elk, is, 
vou will agree, a considerable one—a change of a striking and 
wholesale nature, and yet it is slight compared with some of 
the changes which periodically affected different parts of our 
country in still older geological times. We find warmer and 
colder climates, as indicated by the fossil remains in the rocks 
q succeeding one another, we find land submerged and then 
elevated to form mountain ranges; coral reefs and deposits 
of coal may be found in succession in the same locality, and 
finally, vast volcanic outbursts, far transcending in extent 
anything that we know of at the present day, poured forth 
_ sheets of lava periodically, and have given rise to some of the 
_ most striking scenes of our western coasts, such as the columnar 
rocks of Antrim around the Giant’s Causeway, and the far- 
famed clifis and caves of Stafia. In one cliff on the western 
coast of Mull may be found, interbedded between two great 
horizontal layers of columnar basalt, a deposit of most beauti- 
fully preserved fossil leaves, one of them belonging to the 
Ginkgo tree, living at the present day in Japan. Think of the 
extreme changes of local conditions that that sequence of 
— rocks indicates. 
So far, I have spoken only of the superficial aspects of 
these great changes—matters with which I have no doubt you 
were all familiar; but I must now remind you that these 
superficial aspects represent profound changes in the funda- 
_ mental nature or chemical composition of the deposits that 
