306 Horner's Geological Address, 



fresh accessions to our knowledge of facts of this description, 

 both in Europe and North America, during the past year. 



At Coquimbo, in northern Chile, five narrow, gently slop- 

 ing, fringe-like terraces, rise one behind the other, and, where 

 best developed, are formed of shingle. At Guasco, farther 

 north, the terraces are much broader, and may be called 

 plains, and they run up the valley for 37 miles from the 

 coast. Shells of many existing species not only lie on the 

 surface of the terraces, to a height of 250 feet, but are im- 

 bedded in a friable calcareous rock, which is in some places 

 as much as from 20 to 30 feet in thickness ; and these mo- 

 dern beds rest on an ancient tertiary formation, containing 

 shells apparently all extinct. " The explanation of the forma- 

 tion of these terraces must be sought for, no doubt, in the 

 fact, that the whole southern part of the continent has been 

 for a long time slowly rising, and, therefore, that all matter 

 deposited along shore in shallow water must have been soon 

 brought up and slowly exposed to the wearing action of the 

 sea-beach.'' * He describes a great valley near Copiapo, 

 reaching far inland, the bottom of which, consisting of shingle, 

 is smooth and level ; and states that he has little doubt that 

 this valley was left, in the state in which it is now seen, by 

 the waves of the sea, as the land slowly rose.f He then goes 

 on to state, " I have convincing proofs that this part of the 

 continent of South America has been elevated near the coast 

 at least from 400 to 500, and in some parts from 1000 to 

 1300 feet, since the epoch of existing shells. "J Speaking of 

 the neighbourhood of Valparaiso he says, — " The proofs of 

 the elevation of this whole line of coast are unequivocal ; at 

 the height of a few hundred feet old-looking shells are nu- 

 merous, and I found some at 1300 feet. These shells either 

 lie loose on the surface, or are imbedded in a reddish-black 

 vegetable mould. I was much surprised to find, under the 

 microscope, that this vegetable mould is really marine mud, 

 full of minute particles of organic bodies." § 



So far for instances of changes in the relative level of sea 



* Journal of a Voyage round the World, 2d edit., p. 344. t Ibid., 365. 

 + Ibid., 367. § Ibid., 254. 



