James Cr oil— The South of England Ice-sheet. 257 



V. — On the South of England Ice-sheet. 



By James Croll, of the Geological Survey of Scotland. 



IN the Beader, 14th October, 1865, and afterwards more fully in 

 my papers on the " Boulder-clay of Caithness," ^ and on the 

 " Transport of the Wastdale Crag Blocks," ^ the following were shown 

 from physical considerations to be necessary results, viz. : — 



1. That were the ice of Greenland much thicker than it is at pre- 

 sent, which it evidently was during the Glacial Epoch, it would not 

 float in Davis Straits and Baffin's Bay, and consequently would not 

 break up into icebergs, but would move over upon the North American 

 continent in one continuous mass, and pursue its course southwards, 

 until it gradually melted away imder the influence of the Sun's heat. 



2. That owing to the shallowness of the German Ocean, that sea 

 during the Glacial epoch must have been filled with land-ice moving 

 off Scandinavia, Scotland, and the North of England, and that this 

 ice in its course must have passed over Caithness, the Orkney, 

 Shetland, and Faroe Islands, and in reaching the deep trough of the 

 Atlantic, v/ould break up into bergs, forming a perpendicular wall 

 similar to that observed by Sir James Koss in the Antarctic Kegions. 



3. That the ice from Scandinavia must have filled the entire 

 Baltic, a portion of it passing southward over the plains of North 

 Germany, but the greater portion, however, keeping the bed of the 

 Baltic, would cross over Denmark into the German Ocean. 



4. And as we know from geological evidence that Scotland during 

 the period of maximum glaciation was entirely covered by a con- 

 tinuous sheet of ice of one or two thousand feet in thickness, it is 

 therefore physically impossible that the North of England could 

 have escaped being in a similar condition. 



5. In the paper on the "Transport of the Wastdale Ci'ag Blocks," 

 it was stated that if the summits of the Pennine range were carefully 

 examined, say under the turf, evidence that land ice had passed over 

 them similar to what had been observed by Mr. Bennie and myself 

 on the Pentlands would no doubt be found. These views for several 

 years met with considerable opposition, but they are now beginning 

 to be accepted by geologists. 



6. My object at present, however, is more particularly to refer to 

 another result, which at the time appeared equally to follow from 

 physical considerations (which will be more fully detailed on a 

 future occasion), but as it was one so much opposed to prevailing 

 opinions, I deemed it better not to advance it. The result to 

 which I refer is, if we admit that the Great Baltic Glacier, one or two 

 thousand feet in thickness, passed over Denmark, and of this we 

 have good geological evidence, then it is hardly possible to escape 

 the conclusion that a portion of it at least passed across the south 

 of England, entering the Atlantic in the direction of the Bristol 

 Channel. I have little doubt that in the course of a few years 

 the geological objections to a South of England ice-sheet will as 

 gradually disappear, as they are evidently now doing in reference 

 to a North of England ice-sheet. 



1 Geol. Mag. 1870, Vol. VII. pp. 209 and 271. 



2 Geol. Mag. 1871, Vol. Vlll. page 15. 



DECADE II. — VOL. I. — NO. YI. 17 



