218 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 22, 



Coming south from these high latitudes, I left blocks of Finnish 

 granite in plains near Berlin. In my view Irish glaciation is but a 

 small part of something far greater, which acted continuously from 

 the White Sea down to the Kerry sea-loughs ; and the question now 

 is, what was the nature of the engine that did all this vast glacial 

 work? 



XVII. Land-ice or sea-ice. — Nine years ago my smaller collection 

 of facts led me to account for all glaciation by causes upon the ex- 

 treme scale of the existing arctic current and Greenland ice, which 

 I travelled to look at afloat off Labrador and Newfoundland. As 

 my collection of facts grows, I am led towards something still 

 larger. Even an extension of the climate of Greenland to Ireland, 

 and the shifting of the arctic current to the Baltic, would hardly 

 account for marks which I have seen and which I have tried to 

 describe here and elsewhere. When I review all that I have 

 seen in Finland and Scandinavia, in Iceland and Labrador, in 

 Greece, in the Alps, in Spain, and in America west to the Missis- 

 sippi, and try to combine what I have seen with all that I have 

 learned from writings, maps, and pictures, the whole of my know- 

 ledge of facts leads me to a very great extension of all glacial 

 systems, and to a union of many to form one great Polar system, 

 which moved southwards, and reached far beyond the latitudes of 

 New York and Borne. Near New York, for example, the ice came 

 from Canada, and it was over 2000 feet thick when it passed along 

 the scarped face of the Catskills in the direction of the flow of the 

 Hudson river. 



I thought that icebergs floating in an arctic current would account 

 for horizontal grooves, which I copied by rubbings all the way up 

 the face of the mountain. The uncertainty of the marks upon the 

 top, where water would flow into the next valley, confirmed that 

 opinion. I now begin to think that the ice which passed over the 

 site of New York seawards in the latitude of Madrid may have been 

 part of a crust which spread from the Pole down to that latitude at 

 least, and there was over 2000 feet thick. My theory has grown 

 with my knowledge of facts. My separate icebergs have joined 

 together. To all that I have said in ' Frost and Fire ' I have added 

 more solid ice, and, as I believe, on solid grounds. 



XVIII. Theory. — This is the purport of the story which I have de- 

 ciphered from glacial rock-inscriptions in Ireland and elsewhere : — 

 During a late geological period; land in the northern hemisphere 

 was covered by thick crusts of ice, like ice in the southern hemi- 

 sphere. The crust was continuous then down to low latitudes, as 

 it is now in high southern latitudes. Where it ceased to be con- 

 tinuous, mountains supported large and small local systems, as moun- 

 tains now do. But the separate systems approached and may have 

 reached to the equator, as said by Agassiz. There was then, as 

 there is now, a general movement from north to south in high lati- 

 tudes. Where the water was shallow, glacier-ice grounded ; where 

 it was deep it floated ; and the depths at which ice grounded were 

 proportionate to the depth of the ice. At 2000 feet berg-ice, which 



