860 The American Naturalist. [October, 
tine Republic, and referred to the Pliocene, is no other than the 
Loess in Europe, whose formation took place between the two 
latest glaciations. Adopting this view of the case, the so- 
called Miocene strata probably belong to the great ice period, and 
the Pehuelche stratum represents only the morainic deposits of the 
last ice period. The Plistocene deposits of South America are 
not yet studied in detail, but the glacial deposits I met in South 
Patagonia can be easily distinguished into two different groups: 
those of a former more extended and overarched formation, 
covering not only the lower parts, but also the table mountains of 
over 100 m. in height; and the younger formation, the kettle 
moraines of which are found along the foot of the Cordillera. The 
extension of true glacial deposits within the Cordillera seems to 
be much greater than generally admitted. Twenty years ago 
Raimondi described clearly true moraines from the Cordillera Nev. 
of Ancachs (about 9° s. lat.), reaching down to 2500 m. above 
the sea-level. I myself found moraine deposits in the Cordillera 
of Copiapo (28° s. lat.), about 1200 m. above the sea-level, and 
these observations coincide quite well with those made north of 
the equator by Sievers, who found the traces of former glaciation 
in the Sierra Nevada do Santa Marka and in the Sierra Nevada do 
Tarija. These facts seem to prove that the glacial periods did 
not alternate on both hemispheres, but that they were contempo- 
raneous. In this respect further studies upon the Plistocene 
formations of the Cordillera of South America will be of great 
scientific value. 
Besides the true glacial deposits and the zeolean formation of 
Loess and loam, there exist in South America, especially on the 
High Plateau of Bolivia, like deposits of great extent. Terraces 
and tufa deposits analogous to those of the Great Basin of the 
West indicate a formerly much wider extension of the Lake 
Titicaca over the whole High Plateau from Southern Peru to the 
Argentine frontier. It seems that this former extension of lakes 
in South America coincides also with that of the lakes of the 
Great Basin region. 




