igio.] 



INLAND-ICE OF THE ARCTIC REGIONS. 



63 



highest plateaus which rise above the general table-land of the 

 country. Projecting mountain peaks appear with few exceptions 

 only near the thinnest margins of the ice, where they form either 

 comb ridges or sharp peaks (see Figs. 3 and 4). White and 

 altogether free from surface rock debris except in the vicinity of 

 their margins, these ice-caps offer in this respect additional con- 

 trast to mountain glaciers. The largest of the Iceland ice-caps is 

 the Vatna Jokull, which has an area of 8,500 square kilometers, 



Fig. 3. Maps of the Hofs Jokull and the Lang Jokull (after Thoroddsen). 



while the surfaces of the Hofs Jokull, Lang Jokull and ]\Iyrsdals 

 Jokull each exceed a thousand square kilometers. The shield- 

 like boss of the Vatna Jokull is brought out in the section of Fig. 5.^ 

 Those borders of this ice mass which lie upon the plateau, the 

 northern and western areas, are broadly lobate ; but upon the 

 southern and eastern margins, where the ice mass descends to 

 lower levels and approaches the sea, its tongues sometimes end a 

 few meters only above sea level. It is noteworthy, however, that 

 where deeply incised valleys invade the plateau upon this margin, 

 the lobes of ice push out mainly upon the upland remnants between 



' Hans Spethmann, " Der Nordrand des islandischen Inlandeises Vatna- 

 jokull," Zcitsch. f. Gletscherk., Vol. 3, 1909, pp. 36-43. 



