ANTARCTIC CRUISE. 



331 



stratification in horizontal layers from six inches to four feet in thick- 

 ness. When the icebergs are fully formed, they have a tabular and 

 stratified appearance, and are perfectly wall-sided, varying from one 

 hundred and eighty to two hundred and ten feet in height. These 

 were frequently found by us in their original situation, attached to the 

 land, and having the horizontal stratification distinctly visible. 



In some places we sailed for more than fifty miles together, along a 

 straight and perpendicular wall, from one hundred and fifty to two 

 hundred feet in height, with the land behind it. The icebergs found 

 along the coast afloat were from a quarter of a mile to five miles in 

 length ; their separation from the land may be effected by severe frost 

 rending them asunder, after which the violent and frequent storms 

 may be considered a sufficient cause to overcome the attraction which 

 holds them to the parent mass. In their next stage they exhibit the 

 process of decay, being found fifty or sixty miles from the land, and 

 for the most part with their surfaces inclined at a considerable angle 

 to the horizon. This is caused by a change in the position of the 

 centre of gravity, arising from the abrading action of the waves. 



INCLINED ICEBERG. 



By our observations on the temperature of the sea, it is evident that 

 these ice-islands can be little changed by the melting process before 

 they reach the latitude of 60°. The temperature of the sea (as 

 observed by the vessels going to and returning from the south), 

 showed but little change above this latitude, and no doubt it was at its 

 maximum,' as it was then the height of the summer season. 



During their drift to the northward, on reaching lower latitudes, and 

 as their distance from the land increases, they are found in all stages 

 of decay ; some forming obelisks ; others towers and Gothic arches ; 

 and all more or less perforated : some exhibit lofty columns, with a 

 natural bridge resting on them of a lightness and beauty inconceivable 

 in any other material. The following wood-cut and the tail-pieces of 

 the chapters are sketches of some of them. 



While in this state, they rarely exhibit any signs of stratification 



