DERIVATION OF THE FLORA AND FAUNA 383 



The sediments in this geosyncline are compressed between the BraziHan 

 massif and another massif in the west, the vestiges of which should be looked 

 for in the coast range. Anyhow, "that there was land to the west of the Western 

 Andes cannot be doubted". These authors date the Concepcion-Arauco series 

 to the older Miocene and they do not regard the flora as a coast flora. 



Let us now turn to BkCGGEN, author of a modern handbook on the geology 

 of Chile ijji). To begin with I shall allow myself to quote Florin's summary 

 {pj.4-6) of Bruggkn's earlier writings. 



Until Middle Tertiary times the great Andes and the Coastal Range were ... a 

 continuous upfolded mountain chain subjected to powerful denudation. . . . The principal 

 uplift of the Andes in Chile occurred in the Middle Cretaceous, and altered the 

 palaeogeographical features of the Andean region considerably. 1 he old geosynclinal had 

 been turned into a continental area, at the western verge of which the border of 

 the Pacific Ocean at the end of the Cretaceous occupied approximately the same line 

 as to-day. Marine deposits of Danian ... as well as Palaeocene age are lacking, and 

 at the l)eginning of the Tertiary period the continent probably extended further to 

 the west. 



In the Eocene and Oligocene, respectively, subsidences took place and the ocean 

 encroached more and more on the land. The Concepci6n-Arauco coal measures 

 are coastal deposits, which have been called the Concepci6n Series by Bkuggen. 

 This series, about 400 m. thick, rests unconformably on marine strata of Upper 

 Cretaceous (Senonian) age. The shales containing fossil plants occur in conjunction 

 with intercalated coal seems. . . . The base of this section is of marine origin, and 

 in addition marine layers are intercalated here and there in its middle part, which 

 is otherwise generally built up of freshwater deposits. According to Brl'GGEN the 

 Concepcion Series is overlain by the deposits of the marine Navidad Series, which 

 is upper Oligocene or Lower Miocene in age. Bruggex came to the conclusion that 

 the Concepci6n Series belongs to the Eocene, basing this on stratigraphical as well 

 as on zoo-palaeontological evidence. l"he sediments of this series were according to 

 him deposited on a broad, slowly sinking coastal plain, and subsequently subjected 

 to considerable tilting and faulting, probably in the Miocene. 



Bp:rrv regarded both the Concepcion and the Navidad series as belonging to 

 the Lower Miocene or possibly Upper Oligocene, but according to BrCGGEN 

 this dating holds good for the latter only, while the former is much older, and 

 whereas Bruggen thinks that the Eocene coal flora was deposited in extensive 

 coastal swamps. Berry regarded it as neither limnic nor littoral, but inhabiting 

 a lowland area away from the coast. Florin found that the plant remains were 

 laid down in the vicinity of the sea and that they are too well preserved to 

 have been transported any great distance. 



If it is true that the coast-line, at the end of the Cretaceous, occupied the 

 same position as to-day, one is inclined to believe that the palaeogeography 

 was different before the great uplift occurred in the Middle Cretaceous, when a 

 large scale subsidence ought to have taken place. The oscillations along the 

 coast of central Chile during later times could hardly have involved the area 

 where the submarine ridges are found, so that the possibility to link them to 

 that part of the continent as late as that is small. Consequently attention has 

 been directed farther south, as already suggested. West Patagonia is a region 

 of considerable and late subsidence; the longitudinal valley of central Chile 



