AMONGST THE SOUTHERN ICE. 243 



stones.* Mr. Darwin has published a note on a rock seen on 

 an Antarctic iceberg in lat. 61° S.f 



Dr. Wallicht remarks on the similar scarcity of the appear- 

 ance of stones or gravel on northern bergs. Not one in a 

 thousand shows dirt, &c. He attributes this to the very small 

 disturbance of their centres of gravity which icebergs undergo 

 when floating freely. Stones and gravel may be present in 

 most cases, but remain most frequently invisible under water in 

 the lower parts of the bergs. We dredged up in deep water on 

 two occasions, near the pack-ice. fragments of gneiss and slate 

 which w r ere certainly transported thither by ice. 



On three occasions we saw discolourations of bergs. In one 

 case there was a light yellow band on one surface of a cliff high 

 up, possibly the result of birds' dung which had fallen on the 

 snow when the layer was formed ; it was too high up to be due 

 to Diatoms. 



On another occasion two bergs were passed at a distance, 

 which showed conspicuous black-looking bands, apparently dirt 

 bands. In one of the bergs there were two or three such bands, 

 very broad, parallel to the blue bands, and separated by con- 

 siderable intervals, in which the berg showed the usual strati- 

 fication. In another (coloured plate, fig. 8) two black bands 

 existed at one end of the berg and one at the other. Both were 

 parallel in direction to the blue bands, but the stratification at 

 the end where the two black bands were, was inclined at an 

 angle to that of the remainder of the berg, as if a dislocation of 

 a part of the berg had taken place. These bergs were too far 

 distant to allow of the exact nature of the black bands being 

 determined. 



In none of the numerous bergs did I see any bending or 

 curved vertical bands, grains evidence of a former differential 

 motion in the mass, such as are to be seen on every land glacier. 

 How far the absence of these characteristic lines of motion may 



* Eoss, " Antarctic Voyage," Vol. I, p. 173. London, J. Murray, 1847. 



f C. Darwin, "Notes on a Eock seen on an Iceberg in lat. 61° S." 

 Geog. Soc. Journ. IX, 1839, p. 528, 529. "The Voyage of the 'Eliza 

 Scott,' Commander John Balleny." Journal of Eesearches, p. 251. 



X G. U. Wallich, M.D., F.L.S., &c, "The North Atlantic Sea Bed," 

 Pt. 1, p. 56. London, Van Voorst, 1826. 



R 2 



