228 Formation -of Sea- Cliffs. part ii. 



Cruz from those in the same latitude at the head of the 

 valley. 



I will not pretend to assign to these several and 

 complicated agencies their shares in the distribution of 

 the Patagonian shingle ; but from the several considera- 

 tions given in this chapter, and I may add, from the 

 frequency of a capping of gravel on tertiary deposits in 

 all parts of the world, as I have myself observed and 

 seen stated in the works of various authors, I cannot doubt 

 that the power of widely dispersing gravel is an ordinary 

 coDtingeut on the action of the sea ; and that even in 

 the case of the great Patagonian shingle-bed we have 

 no occasion to call in the aid of debacles. I at one 

 time imagined that perhaps an immense accumulation 

 of shingle had originally been collected at the foot of 

 the Cordillera; and that this accumulation, when up- 

 raised above the level of the sea, had been eaten into 

 and partially spread out (as off the present line of coast) ; 

 and that the newly-spread out bed had in its turn been 

 upraised, eaten into, and re-spread out ; and so onwards, 

 until the shingle, which was first accumulated in great 

 thickness at the foot of the Cordillera, had reached in 

 thinner beds its present extension. By whatever means 

 the gravel formation of Patagonia may have been dis- 

 tributed, the vastness of its area, its thickness, its 

 superficial position, its recent origin, and the great 

 degree of similarity in the nature of its pebbles, all 

 appear to me well deserving the attention of geologists, 

 in relation to the origin of the widely-spread beds of 

 conglomerate belonging to past epochs. 



Formation of Cliffs. — TVhen viewing the sea-worn 

 cliffs of Patagonia, in some parts between 800 and 900 

 feet in height, and formed of horizontal tertiary strata, 

 which must once have extended far seaward — or again, 

 when viewing the lofty cliffs round many volcanic 



