220 GEOLOGY OF PATAGONIA, 



mound, it would form a great mountain chain ! 

 When we consider tliat all these pebbles, countless 

 as the gi'ains of sand in the desert, have been de- 

 rived from the slow falling of masses of rock on 

 the old coast-lines and banks of rivers, and that 

 these fragments have been dashed into smaller 

 pieces, and that each of them has since been slow- 

 ly rolled, rounded, and far transported, the mind 

 is stupified in thinking over the long, absolutely 

 necessary lapse of years. Yet all this gravel has 

 been transported, and probably rounded, subse- 

 quently to the deposition of the white beds, and 

 long subsequently to the underlying beds with the 

 tertiary shells. 



Everything in this southern continent has been 

 effected on a grand scale : the land, from the Rio 

 Plata to Tierra del Fuego, a distance of 1200 

 miles, has been raised in mass (and in Patagonia 

 to a height of between 300 and 400 feet), within 

 the period of the now existing sea-shells. The 

 old and weathered shells left on the surface of the 

 upraised plain still partially retain their colours. 

 The uprising movement has been interrupted by 

 at least eight long periods of rest, during which 

 the sea ate deeply back into the land, forming at 

 successive levels the long lines of clifts or escarp- 

 ments, which separate the different plains as they 

 rise like steps one behind the other. The eleva- 

 tory movement, and the eating-back power of the 

 sea during the periods of rest, have been equable 

 over long lines of coast ; for I was astonished to 

 find that the step-like plains stand at nearly corre- 

 sponding heights at far distant points. The lowest 

 plain is 90 feet high ; and the highest, which I as- 

 cended near the coast, is 950 feet ; and of this, 

 only relics are left in the form of flat, gravel-capped 

 hills. The upper plain of St. Cruz slopes up to a 



