THE CONTINENTAL GLACIERS OF POLAR REGIONS 293 



In both the northern and southern hemispheres those bergs 

 which have floated into lower latitudes have suffered profound 

 transformations. Their exposed surfaces have been melted in the 

 sun, washed by the rain, and battered by the waves, so that they 

 lose their relatively simple forms but acquire rounded surfaces in 

 place of the early angular ones (Fig. 318, p. 291). Sir John Murray, 

 who had such extended opportunities of studying the southern ice- 



FIG. 321. Tabular Antarctic iceberg separating from the shelf ice (after Shackleton) . 



bergs from the deck of the Challenger, has thus described their 

 beauties : 



"Waves dash against the vertical faces of the floating ice island as 

 against a rocky shore, so that at the sea level they are first cut into ledges 

 and gullies, and then into caves and caverns of the most heavenly blue, 

 from out of which there comes the resounding roar of the ocean, and into 

 which the snow-white and other petrels may be seen to wing their way 

 through guards of soldier-like penguins stationed at the entrances. As 

 these ice islands are slowly drifted by wind and current to the north, they 

 tilt, turn and sometimes capsize, and then submerged prongs and spits are 

 thrown high into the air, producing irregular pinnacled bergs higher, pos- 

 sibly, than the original table-shaped mass." 



READING REFERENCES FOR CHAPTERS XX AND XXI 

 General : 



I. C. RUSSELL. Glaciers of North America. Ginn, Boston, 1897, pp. 



210, pis. 22. 

 CHAMBERLIN and SALISBURY. Geology, vol. 1, pp. 232-308. 



