Icebergs upon Drift. 443 



1500 feet of water. The large proportion of the mass which 

 is below the water, must cause them to be very easily and fre- 

 quently stranded. None of those whom I have examined 

 have ever witnessed any movement in the stranded bergs, 

 with the exception of Captain Low, who, in his letter, remarks 

 that icebergs, wJien aground, have the same laboring move- 

 ment that a ship in shore would have, with a heavy cargo 

 and a heavy swell. It is difficult, however, to conceive how 

 a large iceberg, a great proportion of whose mass is below 

 the influence of the swell, could have a movement analoerous 

 to that of a ship which is lifted by every wave. It would 

 seem, therefore, that the formation of hollows in the drift 

 cannot be explained by supposing the grinding and settling 

 down of the stranded berg into the loose materials. 



That an immense lateral force must often be exerted by the 

 pressure of the iceberg upon the shore or shoals against which 

 they may be driven, is shown by a fact stated by Dr. Rich- 

 ardson — that the icebergs in the Arctic seas are driven with 

 such force against the shore, that they push before them, to 

 the height of several feet, every pebble or bowlder which lies 

 upon the bottom. 



The length of time during which icebergs remain aground 

 may have some bearing upon the subject of this inquiry. 

 Captain Simpson, of New Bedford, saw an iceberg, half a 

 mile in length, aground at the mouth of the River La Plata, 

 in the winter, where it was wasting away during two months. 

 Captain Benjamin Pendleton saw one aground in 80 fathoms, 

 near the South Shetlands. Captain Barnum saw one aground 

 in McFarlane's Strait, three or four miles in length. He saw 

 it for two vears, and several of his crew remembered it as one 

 which was seen by Captain Pendleton's party eleven years 

 before. Captain Matthew Luce, of New Bedford, saw one 

 100 feet high, aground in 48 fathoms, on the Banks of New- 

 foundland. The fishermen had fished around it for thirty 

 days. Barriers of this magnitude, remaining for so long a 

 period, must exert a strong influence upon the distribution and 

 deposit of loose materials. Icebergs stranded where the 



