218 MB. E. J. GAKWOOD & DE. J. W. GEEGOEY [May 1 898, 



On the other hand, we found nothing among the morainic beds 

 exactly like the Cromer Till and the Essex Boulder Clay. And given 

 a supply of suitable materials, we see no impossibility in the forma- 

 tion in a quiet bay of a subaqueous deposit that would be indis- 

 tinguishable from a boulder-clay. 



The determination as to which of two types of ice has formed a 

 particular deposit must therefore be left to the general probabilities 

 of each case. 



(2) The Transmarine Passage of Glaciers. 



The rapidity with which glaciers are destroyed when they enter 

 the sea seemed to us a feature of some importance in connexion 

 with the suggested passage of an ice-sheet from Scandinavia into 

 England. Hammer's ^ careful observations upon the Jakobshavn 

 Glacier have given exact data as to the solution of glacier-ice by sea- 

 water at low temperatures : he found that in the winter, when 

 the sea-water was at a temperature below — 1° C, ice submerged 

 beneath it diminished 200 times as quicMy as when exposed to air 

 of the same temperature. It is therefore not surprising that no 

 case is known of the passage of a glacier across any belt of sea, as 

 the old Scandinavian Glacier is assumed to have done. 



It may be urged that an elevation of 250 feet would convert 

 most of the North Sea into dry land ; but the Norwegian Channel, 

 the highest ridge across which lies 140 fathoms deep, would still be 

 left. To drain it, an elevation of 1200 feet would be necessary. Even 

 if this great rise had taken place, the channel would still serve as a 

 serious obstacle to the passage of Scandinavian land-ice to the south- 

 west ; for, as Prof. Bonney ^ has pointed out in an unanswered 

 enquiry in ' Nature," the ice would tend to flow down the valley ta 

 the north. 



The value of another objection to the theory was impressed upon 

 us during the voyage along the Norwegian coast. Some of the 

 Lofoten Islands and smaller islets to the south have unglaciated 

 contours. Their jagged summits must have risen above the ice, 

 like the nunataks on the borders of the Greenland ice-cap. In 

 some places at least, the Scandinavian ice cannot therefore have 

 extended much farther west than the present coast-line. This 

 argument has been repeatedly advanced, and the evidence in its 

 support has been clearly summarized by Sir H. H. Howorth.^ 



1 H. R. J. Hammer, ' Undersogelser ved Jakobsbavns Isfjord og ngermeste 

 Omegn i Vinteren 1879-1880/ Med. om Gronl. vol. iv (1883) pp. 34, 36, 64, & 

 265. 



2 T. G. Bonney, ' The Scandinavian Ice- sheet,' Nature, vol. xlix (1894) 

 pp 388-389. 



3 H. H. Howorth, 'The Glacial Nightmare & the Flood' (1893), vol. ii, 

 pp. 703-710 ; ' On the Erratic Boulders & Foreign Stones of the Drift- 

 deposits of Eastern England,' Geol. Mag. 1897, p. 155. For arguments in 

 support of this view from a dijBferent line of consideration, see A. M. Hansen,. 

 * The Origin of Lake-basins/ Nature, vol. xlix (1894) pp. 364-365. 



