124 THE OCEAN. 



turn was refrozen, soon changed the lowest stratum 

 into a mass of dense and transparent ice. Centuries 

 of alternate winters and summers have thus produced 

 ao-oreo-ations of enormous bulk. Scoresby mentions 

 one of eleven miles in length, and four hundred feet 

 in height at the seaward edge, whence it slopes up-- 

 ward and backward till it attains the height of six- 

 teen hundred feet; an inclined plane of smooth 

 unsullied snow, the beauty and magnitude of which 

 render it a very conspicuous landmark on that inhos- 

 pitable shore. The upper surface of a land iceberg is 

 usually somewhat hollow, and during the summer the 

 concavities are filled with pools or lakes of the purest 

 water, which often wears channels for itself through 

 the substance, or is preeipitated in the form of a 

 cataract over the edge. The water freezing in fissures 

 thus produced, and expanding with irresistible force, 

 tears off large fragments from the outer edge, which 

 are precipitated into the ocean; and high spring 

 tides, lashed by storms, undermine portions of the 

 base, and produce the same effect. The masses thus 

 dislodged float away, and form ice-islands. When 

 newly broken, the fracture is said to present a 

 glistening surface of a clear greenish blue, approach- 

 ing an emerald green ; but of such as I have myself 

 had an opportunity of examining in Newfoundland, 

 the hollows Avere of the purest azure. 



" On an excursion to one of the Seven Icebergs," 

 says Mr. Scoresby, "in July, 1818, I was particu- 

 larly fortunate in witnessing one of the grandest 

 effects which these polar glaciers ever present. A 

 strong north-westerly swell having for some hours 



