and contemporaneous Deposits of South America. 



423 



diately joining beds, and likewise from the peculiarity of the flexures in Fig. 2, I 

 could not at the time persuade myself it was by ordinary violence from below, and 

 no other solution occurred to me. Mr. Lyell* has shown, that in the districts 



Fig. 3. 





Gregory Bay. (For commencement of description see last page.) 



in Europe where the till and boulders occur, most curiously contorted layers are 

 directly superimposed on undisturbed beds, and he suggests as one explanation, 

 the lateral force exerted by stranded icebergs. As we have here also the till and 

 boulders, the forcing up and mingling together of these sedimentary deposits, have, 

 perhaps, been effected by this same agency f ; an agency, however, which in most 

 cases appears merely to have prevented the separation of the drifted materials into 

 distinct layers. 



3. Island of Chiloe.- 



Passing from the extreme southern part of the continent along the west coast, 

 I did not land south of lat. 47°- It was, however, between lat. 49° and 50° that the 

 fragment of granite, described in my Journal, was seen floating on an iceberg 

 twenty miles from its parent glacier, and therefore we may feel sure that erratic 

 boulders occur in this space. Between lat. 47° and the southern extremity of 



* Philosophical Magazine, 1840, p. 379 : Mr. Lyell on the Boulder Formation, &c., Proceedings, vol. iii. 

 p. 178. 



t Capt. W. Graah, in his Expedition to the East Coast of Greenland, states that there is a part of the 

 coast which derives its name of Puisortok from ice " shooting up from the bottom of the sea in such a 

 manner and in such masses, as in many years to make it utterly impassable." The cause of this singular 

 phaenomenon is unknown. Capt. Graah suggests amongst other causes, that these masses may be the 

 remains of icebergs frozen to the bottom ; but is it not much more probable that the icebergs were first 

 driven deeply into the soft bed of the sea, and that they did not become disengaged until their whole 

 upper parts had been washed away and their buried sides loosened by the melting of the ice ? 



3 I 2 



