THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE V. VOL. III. 



No. XII. — DECEMBER, 1906. 



O^^IC3-I3S^JL3L .A_I?.TIGLES. 



I.— The Antarctic Ice-oap. 



By H. T. Ferkar, M.A., F.G.S., 



Geologist to the late " Discovery" Antarctic Expedition, 

 of the Survey Department, Cairo. 



IN a recent number of the Geological Magazine, Dec. V, VoL III, 

 March, 1906, p. 120, there is an article by Prof. E. H, L. Schwarz 

 which deals with the thickness of ice-caps during the various Glacial 

 periods. At the outset Professor Schwarz takes the data furnished 

 by Captain Scott's narrative of the voyage of the " Discovery " as the 

 main support of the physicists' contention that an ice-sheet cannot 

 exceed 1,600 feet in thickness. 



It is true that at the present day no ice more than 1,600 feet has 

 been recorded. Dr. Nausen estimates the thickness of the Greenland 

 ice-sheet to be nearly four times that amount, and, judging by the size 

 of the icebergs said ^ to have been met with in the Southern seas, 

 maintains ^ that the Antarctic Ice-cap must attain a very great 

 thickness. These estimates, however, may be neglected, as the 

 recent expeditions seem to show that the size of icebergs recorded 

 in the Antarctic seas has been exaggerated. Both Von Drygalski^ 

 and Captain Scott* show that in times past the ice-caps of Greenland 

 and South Victoria Land respectively attained a much greater 

 thickness than they do now, and if we wish to prove that ice-sheets 

 ever exceeded the 1,600 feet limit we have only the traces left by 

 previous Glacial periods to fall back upon. 



The thickness of an ice-sheet or iceberg, estimated by means of 

 the unsubmerged height, is only very approximate. Von Drygalski 

 gives 300 feet as the maximum height above water, and maintains 

 that any iceberg which is higher than 300 feet must have turned 

 over. In high latitudes the air is commonly misty, though in certain 



1 H. C. Russell : JTournal of the Royal Society of 'Nevf South Wales, vol. xxxi 

 (1897), p. 2-11, reference number 172. 



2 Nausen : Nature, vol. Ivii (1898), p. 424. 



3 Drygalski : Greenland Expedition, p. 33. 



* Scott: Geog. Journ., April, 1905, p. 360. 



DECADE v. VOL. III. NO. XII. 34 



