HEARD ISLAND. 



223 



fantastic irregularly conical masses, composed of very numerous 

 thin layers of scoriae, conspicuous because of their varying and 

 strongly contrasted colours and very irregular bedding. The 



BROKEN-DOWN CRATER, WHISKY BAY, WITH SNOW UPON IT. 



lava flow is seen in section in the low cliffs forming; the coast- 



o 



line of the harbour. 



The present condition of Heard Island is evidently that which 

 obtained in Kerguelen's Land formerly. Glaciers once covered 

 Kerguelen's Land almost entirely and dipped down into the sea. 

 It is, however, an extraordinary fact that Heard Island, only 300 

 miles south of Kerguelen's Land, should thus still be in a 

 glacial epoch, whilst in Kerguelen's Land, a very much larger 

 tract, the glaciers should have shrunk back into the interior, and 

 have left so much of the land surface entirely free of ice, the ice 

 epoch being there already a thing of the past. 



The great height of Big Ben, and consequent largeness of the 

 area where snow constantly accumulates and cannot be melted, 

 no doubt accounts to a considerable extent for the peculiar 

 conditions in Heard Island. A similar rapid descent of the 

 snow-line within a few degrees of latitude occurs in the Chilian 

 Andes,* so great is the chilling influence of the vast southern sea. 



* Grisebach, "Die Vegetation der Erde." Leipzig, 1872. 2. Bd. 

 s. 467. Ibique citato. 



