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 
aggregations 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 precipitated 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 were 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 
