118 



bulletin: museum of comparative zoology. 



Darwin's scheme of geological formations in Chile. 

 (Compiled from "Geological observations.") 



Newer Tertiary, includ- 

 ing the basin-plains 

 of Chile. 



Concepcion formation. 



Upper Cretaceous? 



Cretaceo-Oolitic; Gyp- 

 seous formation. 



Metamorphic series. 



Superficial saliferous deposits of Iquique. 



Salt and nitrite of soda, 3,000 ft. above 



sea-level. 

 Beds of gravel, red sandy clay; lava, 



pumice beds, overlying calcareous tufa. 



Sandstones with lignites, silicified wood, 

 and "concretions" carrying marine 

 shells. Eruptions. 



Tuffs and submarine lava of Uspallata 

 section; conglomerates of valley of 

 Tenuyan. 



Upheaval in central Chile forming 

 Cumbre and other ranges. 



Coarse conglomerates, siliceous sand- 

 stones, dark mudstones. limestone, 

 pseudohornstones, tuffs, and vast beds 

 of gypsum, with marine fossils and sili- 

 cified trunks of fir-trees at Los Hornos. 



Eruptions of purplish claystone and 

 greenstone porphyries, etc. 



Metamorphic schists, plutonic rocks, and 

 more or less altered clayslate. 



The more recent work on the geology of Chile has been summarized 

 by Mr. Lorenzo Sundt (1909, p. 37-44). According to this geologist, 

 the sedimentarv formations now recognized in Chile are as follows: — 



