Association of American Geologists. and Naturalists 161 
gales which prevail in that region of the Pacific during so large.a por- 
tion of the year, into the current setting constantly to the northward 
along the whole west coast of South America, it might have floated to 
the verge of the tropics ere it dissolved entirely, or perhaps been 
stranded somewhere about the shores of the Chiloan Archipelago. 
The attention of the Association was called to the fact of such large 
masses of rock, which were undoubtedly once at the bottom of the 
berg, being exposed on its face or sides. Mr. Couthouy conceived that 
the dissolution below the surface by the action of the water, and above 
it by that of the weather, being unequal in different portions of the 
berg, especially when it was aground, and consequently oné side 
more constantly exposed to the sun’s rays than the other; the equilib- 
rium would be occasionally destroyed, the result of which would be 
an overturn, like that witnessed upon.the Grand Banks, bringing to the 
surface portions of the mass containing rocks and earth. The U. 8. 
ship Peacock, during her last cruise of discovery in the Antarctic Ocean, 
while attempting to penetrate the great barrier of ice, was seriously 
injured, and narrowly escaped utter destruction, from the separation and 
toppling down of a huge fragment of an iceberg. Had not this latter 
been still attached to the main body, there can be no question but that 
one of the violent overturns referred to, would have followed such a 
change in the proportions of the berg. Again, in the case of a drifting 
island, where from its rotary motion it is probable the waste from eXxpo- 
sure would be nearly equal on all sides, it is evident that the side in 
which the rocks were imbedded, would, owing to their ‘specific gravity 
being much greater than that of ‘the ice, gradually preponderate, and 
either produce ggsudden and violent change of axis, or slowly. settle 
by no means of improbable actu 
indeed, was: merély-a statement of what. had really taken place in the 
great-iceberg last described. Suppose an island of ice to be detached 
from the great southern barrier, having its base loaded with rocks, 
&c., and after drifting several hundred miles northward, to experience 
an.overturn bringing these rocks to the surface. It then floats on for a 
considerable distance farther, till. from the equilibrium being again 
destroyed, the rocky portion settles down and resumes its asieioal-p posi- 
tion. ‘These alternations may occur several . fines asain ( 
Vol. xm, No. 1,—April-June, 1842. 
