4o: 



C. SKOTTSBERG 



Finally, let us try to reconstruct the history of our islands, beginning with 

 the time when there existed a "Tierra de Juan Fernandez" in BrCggen's sense. 

 It must have become isolated and reduced in size rather early. We do not know 

 if the fauna included vertebrates other than birds; if it did they did not survive 

 the long volcanic period. Unfortunately we know too little of their history in 

 Chile, when they hrst appeared in modern forms, and so forth. The absence of 

 all gymnosperms is difficult to explain. The Eocene flora of Chile contained several, 

 Araucaria, Libocedrus and Podocarpus, all still living there and accompanied by 

 I'itzrova, SaxcgotJiaca, Pilgerodoidroji and Dacrydhim, and even if no close land 

 connection existed, some of them ought not to have had much greater difficulties 

 to get transported across the water barrier than some of the angiosperms found 

 on the islands. If, on the other hand, a land bridge existed, I can see no obvious 

 reason why conifers did not use it or, if they did, why they didn't take possession 

 of the new volcanic soil. Introduced araucarias, pines and cypresses do well on 

 Masatierra. The only possibility, remote perhaps, could be that they had not been 

 able to spread as far as to Juan Fernandez when the connection was cut. Their 

 absence gives us no clue to the time when this happened. 



Another element in the Chilean flora would seem to come to our rescue, the 

 XotJiofagiis flora. In my sketch of 1925 [2JI. 33) I expressed the idea that "the 

 connections between the islands and the main land were severed before the south 

 Chilean flora assumed its present composition, and also before the advancing 

 XotJiofiii^us flora reached these latitudes", and BrCcgen is of the same opinion. 

 He states that tropical South America is the ancestral home of much of the 

 Chilean forest flora, and adds: 



Pero, la actual flora de Chile central contiene, ademas, una mezcia con una flora 

 dc (lima mas fresco, (jue despues de la separaci6n de la Tierra de Juan Fernandez 

 inmif^ro y (jue se caracteriza por los generos Nothofagus, Araucaria, etc. 



Araiicaria was found in the Pichileufu beds which are supposed to be Eocene, 

 whereas the southern beeches appear in this latitude considerably later. In the 

 Magellanian region Dl SKN, as we have seen, distinguished two horizons, a lower, 

 Oligocene, with Xoiliofagus, and an upper. Lower Miocene, \m\\\\ Araucaria. Accord- 

 ing t(j Hi<i'(;(;kn the separation of Juan Fernandez from Chile took place during 

 the Oligocene Xavidad transgression. We would think that, if the bridge lasted 

 longer, the XotJiofagus flora ought to have invaded Juan Fernandez and to have 

 found suitable stations in the montane belt, and that the rising volcanic islands 

 offered acceptable habitats for a genus of such wide physiological amplitude. 



Anyhow, during the final upheaval of the Andes when, in any case, most 

 of the land disappeared, leaving the submarine ridge with the rising volcanic 

 masses standing. Central Chile definitely ceased to be a source of the island flora. 

 This Chilean flora is, as Reiciie pointed out, a product of the Andes with addition 

 of an Antarctic element. 



Submergence resulted in the displacement of the vegetation belts and in much 

 loss of life when the volcanic eruptions began and lava flows and other ejected 

 material covered part of the country. Long before that, important changes had 



