152 J. E. Marr—The Work of Ice- Sheets. . 



their summits standing up from the surrounding ice as islets of rock 

 known as " Nunatakker," until finally nothing is seen but a gently 

 sloping plain of ice extending into the interior. The "Nunatakker" 

 of Jensen, situated at a distance of over forty English miles from the 

 edge of the ice-sheet, have a height of over 5000 feet above the sea. 

 The ice to the east of them is elevated to a height of 5000 feet, 

 whilst to the west it is considerably lower, as it becomes heaped up 

 against the eastern side of the barrier like running water against a 

 projecting rock. For a considerable distance to the west the ice is 

 nearly horizontal, and afterwards it slopes downwards at a very 

 small angle, having at first an average of 0° 49' and afterwards at 

 greater angles, which do not exceed 2° 14'. 



The effects produced upon the movements of the ice by these 

 partially buried barriers are most remarkable, and remind one 

 strongly of the phenomena described by Messrs. Tiddeman and 

 Goodchild in the area of and around the Pennine Chain. 



If we examine the map of the directions of movement of the ice in 

 Phillips's Geology of Yorkshire, third edition, part i. p. 9, and read 

 it in the light of recent discovery, we are at once struck with the 

 similarity of the conditions to those now presented by Jensen's and 

 Dalager's "Nunatakker," as described in part i. of the "Meddelelser." 

 This map may be taken to represent roughly the emergence of the 

 Pennine " Nunatakker " above the ice about the period of maximum 

 glaciation. The whole of the low tract to the west of the Pennines 

 was occupied by the great masses of ice which, as shown by Messrs. 

 Tiddeman and Goodchild,^ came from the Lake District hills and 

 from those of the south of Scotland. This ice passed over the Pen- 

 nines at Stainmoor, and by the low watershed separating the valleys 

 of the Eibble and Aire further to the south. The Scotch ice and 

 apparently some of the Lake District ice passed over the low land 

 between the northern extremity of the Pennine Chain and the 

 Cheviot Hills, and it is generally recognized that this ice spread out 

 far and wide over the Yorkshire plains. 



This ice is considered by Mr. Goodchild not to have risen much 

 above the 2400 feet contour-line in the Dale district examined 

 by him, and judging from his map, the highest marks of glacia- 

 tion occur here, where the ice would be heaped up against the 

 Pennine Chain. In the district to the south described by Mr. 

 Tiddeman, the marks of glaciation occur up to a height of 1400 feet 

 on Bowland Knotts. The distance from Baugh Fell, where the' 

 highest marks are found in Mr. Goodchild's district, to Bowland 

 Knotts, is over twenty miles, giving a fall of not more than 1 in 110 

 for the surface of the ice-sheet. 



In the case of the Greenland "Nunatakker," we find that the 

 greater part of the ice passes round the buried ridge of rock, 

 describing a nearly complete circle, but that the upper portion flows 

 over the depressions which separate the different " Nunatakker," 

 and moves over the main mass of ice on the lee-side of the obstruct- 

 ing ridge, usually at right angles to the course of that ice, and that 

 ^ Q. J. G. S. vol. xxviii. p. 471, and vol. xxxi. p. 55. 



