Tertiary sediments are found at scattered localities throughout the continent of South America, and the Argentina Tertiaries in particular have been extensively exploited in connection with the study of the varied vertebrate fossils which they contain. Marine Tertiary deposits are found in the latter Tegion as well as around the margin of the Brazilian plateau; they are widely distributed along the west coast, and in the Andean region they are scattered from Colombia and Venezuela to Tierra del Fuego and beyond. Our knowledge of all of these is very fragmentary and is limited for the most part to incidental descriptions in connection with the study of the contained floras or faunas rather than on detailed areal and stratigraphie work.
In the present brief contribution the discussion is centered on the pre-Pliocene Tertiary of the Andean region and of the west coast, since the data at hand seem sufficient for tentative . . .