218 



PATAGONIA. 



April, 1834. 



bed of the river. If I had space I could prove that South 

 America was formerly here cut off by a strait joining the 

 Atlantic and Pacific oceans, like that of Magellan. But it 

 may yet be asked, how has the solid basalt been removed ? 

 Geologists formerly would have brought into play, the 

 violent action of some overwhelming debacle ; but in this 

 case such a supposition would have been quite inadmissible ; 

 because the same step-like terraces, that front the Patagonian 

 coast, sweep up on each side of the valley. No possible 

 action of any flood could have thus modelled the land in 

 these two situations ; and by the formation of such terraces 

 the valley itself has been hollowed out. Although we know 

 that there are tides, which run within the narrows of the 

 Strait of Magellan at the rate of eight knots an hour, yet we 

 must confess it makes the head almost giddy to reflect on the 

 number of years, century after century, which the tides 

 unaided by a heavy surf, must have required to have cor- 

 roded so vast an area and thickness of solid rock. Never- 

 theless, we must believe that the strata undermined by the 

 waters of this ancient strait, were broken up into huge frag- 

 ments, and there lying scattered on the beach, were reduced 

 to smaller blocks, then to pebbles, and lastly to the most 

 impalpable mud, which the tides drifted into the bed, either 

 of the Eastern or Western Ocean. 



With the change in the geological structure of the plains 

 the character of the landscape likewise altered. While 

 rambling up some of the narrow and rocky defiles, I could 

 almost have faacied myself transported back again to the 

 barren valleys of St. Jago. Among the basaltic cliff's, I found 

 some plants which I had seen nowhere else, but others I 

 recognised as being wanderers from Tierra del Fuego. These 

 porous rocks serve as a reservoir for the scanty rain-water, 

 and consequently on the line where the igneous and sedi- 

 mentary formations unite, several small springs (most rare 

 occurrences in Patagonia) burst forth; and they could be 

 distinguished at a distance by the circumscribed patch of 

 bright green herbage. 



