Park. — The Great let Age of IS ew Zealand. 60o 



coast ; and the smooth contours, domed crests, and U-shaped valleys in 

 Southland and eastern Otago woiild indicate that this was actually the 

 case. 



The maximum thickness of the ancient ice-sheet in North America has 

 been estimated at 7,000 ft. ; and the southern limit of the ice in Illinois 

 was not less than 1,500 or 1,600 miles south of the Labradorian* centre of 

 movement, reaching down to 37° 30' N. latitude. 



The distance from the Livingstone centre of movement west of Waka- 

 tipu to the present east coast is about a hundred and ten miles, and from 

 Kingston about eighty-five miles. 



If the North American ice-sheet, 7,000 ft. thick, was able to travel 

 1,500 or 1,600 miles from its centre of movement, does it seem impossible 

 for the Wakatipu sheet, 6,000 ft. thick at Kingston, to travel a hundred 

 miles ? The answer is that it not only reached the present coast-line, but 

 in all probability extended far beyond it as the result of gravitation stress. 



Nansen found that the surface of the Greenland ice-sheet rose with a 

 steep gradient at either margin, and flattened as the summit was reached. 

 In the central parts of the icefield he found that the gradient varied from 

 26 ft. to 27 ft. per mile. For larger sheets Chamberlin and Salisburyf 

 believe that the slope was probably less. 



Discussing the thickness of the ice-sheet that covered northern Europe, 

 GeikieJ says that the ice may have been 6,000 ft. or 7,000 ft. thick in 

 Scandinavia, and 4,000 ft. or 5,000 ft. as far south as Scotland, where ice 

 grooves have been found at a height of 3,000 ft. above the sea. 



Now, we know that the southern limit of the ice-sheet in Great Britain 

 was the Thames Valley, a distance of over three hundred miles from the 

 Scottish Highlands — the centre of movement. This distance has an im- 

 portant bearing on the gradient of the ice-sheet, for, if we take the thickness 

 at 5,000 ft., it is obvious that the gradient of the British sheet must have 

 been only 1 in 17. 



If we take 500 ft. as the height of the abruptly sloping ice at the 

 terminal face of the Otago ice-sheet, we have a vertical height of 5,500 ft. 

 remaining ; which, with a gradient of 50 ft. per mile, would give a flow 

 of 110 miles, more than the distance from Wakatipu to the present coast- 

 line. The Labradorian ice-sheet that extended southward to the mouth 

 of the Missouri could not have had a gradient exceeding 5 ft. per mile, 

 except we are to believe that the thickness of the ice-sheet greatly exceeded 

 8,000 ft., which Salisburj^ says was not the case. With a gradient of 20 ft. 

 per mile, the thickness would amount to the exaggerated thickness of 

 32,000 ft. The gradient of 50 ft. per mile I have assumed is probably 

 far in excess of the actual mean gradient of the Otago ice-sheet. 



It is noteworthy that Captain Hutton, in his map of the ancient glaci- 

 ated area§ of New Zealand, shows nearly half of the South Island covered 

 with a continuous ice-sheet. 



My discoveries \\\ the Wakatipu region in 1907-8 prove that the 

 glaciation of the South Island attained a magnitude hitherto unknown 

 to Hutton and other New Zealand geologists. My own view of the 



* Chamberlin and Salisbury, " Geology," vol. iii, p. 357. 



t Chamberlin and Salisbury, " Geology," vol. i, p. 358. 



% A. Geikie, " Geology," vol. 



§ F. W. Hutton, pamphlet, " Report of the Research Committee appointed to col- 

 lect Evidence as to Glacial Action in Australasia in Tertiary or Post-Tertiary Times,*"^ 

 p. 12. 



