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. 
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. 
Upper Cretaceous? 
Cretaceo-Oolitic; Gyp- 
seous formation. 
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 series. 
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 sedimentary formations now recognized in Chile are as follows: — 
