242 A NATURALIST ON THE " CHALLENGER." 



There can hardly be a doubt that the ice must be of 

 increasing density from its summit downwards. 



Several small bergs were passed, which showed hardly 

 any blue stratification in their cliffs ; the top surfaces of 

 these showed rounded conical hillocks, and a general appear- 

 ance of formation by wind drifting of the snow. What 

 few bands were present, were conformable in curve with 

 the irregular surface. It appeared as if the denser mass 

 w T ere here all below water, and not large enough to float 

 more than the lighter, more friable and recent top deposit 

 above the water.* 



Antarctic icebergs have been met with by merchant vessels 

 in higher latitudes, varying in length from one to seven, or even 

 ten miles in length. In 1854, a vast body of ice was passed 

 and reported by twenty-one merchant ships in lat. 44° to 40° S., 

 long. 28° to 20° W., a latitude corresponding to that of the 

 northern coast of Portugal. The ice mass, which was probably 

 a group of icebergs locked together, was in the form of a hook, 

 60 miles long by 40 broad, enclosing a bay 40 miles in breadth ; 

 none of the ice masses composing it exceeded 300 feet in 

 height, t 



During the short time that we were amongst the icebergs 

 we met with none that bore upon them any moraines or rocks 

 which could with certainty be determined as such. The scarcity 

 of such appearances has been remarked by former voyagers. 

 Nevertheless, there are numerous instances of rocks having been 

 seen on southern bergs. 



Several observers have met with rocks on bergs. Wilkes 

 saw many such; Eoss also, and the latter, on one occasion 

 landed a party on a berg on which there was a volcanic rock 

 weighing many tons, and which was covered with mud and 



* For a magnificent series of large photographic views of . Arctic 

 icebergs and ice scenery, see " The Arctic Regions," by William Bradford. 

 London, Sampson Low and Marston, 1873. 



t " South Atlantic Directory," p. 94. W. H. Rosser, and J. F. Murray. 

 London, 1870. Here will be found a general account of icebergs in the 

 South Atlantic. On same subject see J. T. Towson, "On Icebergs in 

 the Southern Ocean." Liverpool, 1859. 



