Jame& Croll — On the Glacial Epoch, 347 



raise the general level of the ocean one foot, and the one mile of ico 

 melted off would raise the level 200 feet. This 200 feet of rise 

 resulting from the melted ice we must add to the rise resulting from 

 the displacement of the earth's centre of gravity. The removal 

 of the two miles of ice from the Antarctic Continent would displace 

 the centre of gravity 190 feet, and the formation of a mass of ice 

 equal to the one-half of this on the Arctic regions would carry the 

 centre of gravity 95 feet further ; giving in all a total displacement 

 of 285 feet, thus producing a rise of sea-level at the North Pole of 

 285 feet, and in the latitude of Edinburgh of 234 feet. Add to 

 this the rise of 200 feet resulting from the melted ice, and we have 

 then 485 feet of submergence at the Pole, and 434 feet in the lati- 

 tude of Edinburgh. A rise to a similar extent might probably take 

 place after the period of maximum glaciation, when the ice would be 

 melting on the northern hemisphere more rapidly than it would be 

 forming on the southern. 



If we assume the Antarctic ice-cap to be as thick as is represented 

 in the diagram, the extent of the submergence would of course be 

 double the above, and we might have in this case a rise of sea-level 

 in the latitude of Edinburgh to the extent of from 800 to 1000 

 feet. But be this as it may, it is evident that the quantity of ice on 

 the Antarctic Continent is perfectly sufficient to account for the sub- 

 mergence of the Glacial epoch, for we have little evidence to 

 conclude that the general submergence much exceeded 400 or 500 

 feet.^ We have evidence in England and other places of submer- 

 gence to the extent of from 1000 to 2000 feet, but these may be 

 quite local, resulting from subsidence of the land in those particular 

 areas. Elevations and depressions of the land have taken place in 

 all ages, and no doubt during the Glacial epoch also. 



In favour of this view of the cause of the submergence of the 

 Glacial epoch, it is a circumstance of some significance, that in every 

 part of the globe where glaciation has been found, along with it, 

 evidence of the submergence of the land has also been found. The 

 invariable occurrence of submergence along with glaciation points 

 to somfe physical connexion between the two. It would seem to 

 imply, either that the two were the direct effects of a common cause, 

 or that the one was the cause of the other ; that is, the submergence 

 the cause of the glaciation, or the glaciation the cause of the sub- 

 mergence. There is, I presume, no known cause to which the two 

 can be directly related as effects. Nor do I think that there is any 

 one who would suppose that the submergence of the land could have 

 been the cause of its glaciation, even although he attributed all 

 Glacial effects to floating ice. The submergence of our country 

 would, of course, have allowed floating ice to pass over it had there 

 been any to pass over ; but submergence would not have produced 

 the ice, neither would it have brought the ice from the Arctic regions 

 where it already existed. But although submergence could not have 



1 In a former paper I considered the eflfects of another cause, viz. the melting of 

 polar ice resulting from an increase of the Obliquity of the Earth's Orbit. — Trans. 

 Glasgow Geol. Soc. vol. ii. p. 177. Phil. Mag. June, 1867 (Supplement). 



