"From 2 million years ago" . . . . . . . . "On the distribution of the erratic boulders and on the contemporaneous unstratified deposits of South America" . . "On the distribution of the erratic boulders and on the contemporaneous unstratified deposits of South America"@en . . . . . . . . . . "... On the distribution of the erratic boulders and on the contemporaneous unstratified deposits of South America"@en . . . . . . . . . . . "Boulders." . . . . "Geology, Stratigraphic." . . "Quaternary Geologic Period." . . "Geology South America." . . "Geology, Stratigraphic Quaternary." . . "South America." . . "Geology." . . "Glacial epoch." . .