Cause of the Glacial Period 
These successive submarine plains and plateaus were the result of littoral denudation at times when the continents, 
high above water, were gradually sinking (like the smaller “Raised Beaches” during uprise of land), with such 
intervals of stability as allowed the destructive action of the air, water, and ice to make great horizontal notches along 
coasts and across river-channels. Consequently certain portions of the continents have been in former times at least 
two miles higher above the sea-level than they are now. With this elevation and wider extent of land the climate 
must have been much colder, even frigid enough for what has been termed a “ Glacial Age.” 
Other points also are considered by the author. It was in late geological times that the coasts of the Northern 
Atlantic Ocean, both on the American and the European side, and across its northern region, had an elevation high enough 
for an arctic climate. ‘The equatorial current could not then have had the heat it now obtains by its local confinement 
in the torrid Gulf of Mexico; and the vicinity of the snow-laden coasts of the North Atlantic would have reduced 
the equatorial warmth ; so that it would have had little influence in ameliorating the climate of North-Western Europe 
in the “Glacial Age.” 
He also intimates that, on account of the slow and unequal movements of the earth’s surface, the coming and 
going of arctic conditions must have been different at times and places ; and the glaciation of one region would not 
be quite synchronous with that of another. At all events a great part of North America, with North-Western Europe, 
had a glacial climate in late Pliocene or early Pleistocene times. 
Mr. Warren Upnam, F.G.S.A., writes :— 
Sr. Paut’s, Minnesota, Fanuary 3rd, 1898. 
The explanation of the climatic changes and ice accumulations of the Glacial epoch presented in Professor Hull’s 
paper, with its accompanying map, seems to me a most valuable addition to our understanding of this very exceptional 
and unique geological epoch. There can be no doubt that the epeirogenic uplifting ot the lands on each side of the 
North Atlantic Ocean produced important changes of the Gulf Stream and of its influence on the climate of Europe. 
The lowering of the temperature of that great sea current may well have been a chief element in the causation of the Ice 
Age in the British Isles and Northern Europe, supplementing the effect due to the greatly increased altitude of the 
land, of which the fjords bear testimony. 
In North America, however, where our storms and waves of varying barometric pressure and temperature sweep 
from west to east and north-east across the country, thence passing over the North Atlantic, we must, I think, ascribe 
the chief part in the production of the Glacial epoch to the high elevation of the land, probably 3000 to 5000 feet above 
its preglacial and its present height. 
Professor Hull’s map might indeed well be coloured farther into the present sea area between Europe and Green- 
land, to the submarine contour of 450 or 500 fathoms, as for the Blake Plateau of America. If the preglacial uplift of 
the sea-bed between the Atlantic and Arctic Oceans was so great, which is very probable, these oceans were completely 
separated by land,-and the Gulf Stream and warm superficial oceanic drift from it were wholly excluded from contact 
with Scandinavia. That condition, in combination with the high land uplift, gives an ample explanation of the origin 
of the Ice Age in Europe, which seems to have been essentially contemporaneous with that of North America. 
The Rev. R. Asuinctron Butien, B.A., F.G.S., writes :— 
There can be but one opinion about the interest and importance of the theory set forth by Professor Hull. 
Huxley leaves undecided the influence of the Gulf Stream in ameliorating the climate of Great Britain, and hints at 
the possibility of warm currents being due to the dominant south-westerly winds of the temperate part of the Atlantic. 
Under any circumstances, however, the lowering of the temperature of the Gulf Stream would have a marked effect on 
the temperature of the ocean and the air in the North Atlantic, and would affect the assumed currents due to the south- 
westerly winds. 
To my mind the amelioration of our climate is mainly due to the Gulf Stream or to subsidiary currents proceeding 
from it. The existence of such fragile West Indian shells as Spirula Perouii on Portrush Beach, N. Ireland, and at 
Woolacombe, Devon, perfectly uninjured,” points to a branch of the Gulf Stream touching first the Irish and then the 
Devon coast. Mr. R. Welch of Belfast and friends have collected eight to ten ata time, especially in September.® 
Tellina radiata, another West Indian shell, has occurred at Courtmacsherry Bay, S.W. Ireland, and other places. Sir A. 
Geikie* points to the occurrence of West Indian plants on the Irish coast as having been drifted across the Atlantic 
from west to east, or north-east. 
In September 1897, in the Allan liner Parisian, from Liverpool to Montreal, the sea-water temperatures were 
logged approximately as follows :— 
September roth about 55° 20’ N. lat. g° o! W. long. 58° F. 
» rath 5, 56°25’ 4, 25°31. 5 55°F. 
» gE my GO 2H By ae mB I 
» 14th » 55° 12! » 43° 6! » 48° FB. 
mp MD gy SY py 
Re 16th, Gulf of St. Lawrence, Cape Norman, E.S.E. 33° F. 
1 Physiography, 2nd edit. p. 174- 2 Science Gossip, 1897, p. 150. 3 Ibid. 4 Geikie, Physical Geography, p. 139. 
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