Note 13 — Chapter IV · ON THE FORMATIONS OF THE PAMPAS.
Reading edition
M. d’Orbigny has given (“Voyage,” Part. Géolog., p. 37) a detailed description of this section, but as he does not mention this lowest bed, it may have been concealed when he was there by the river. There is a considerable discrepancy between his description and mine, which I can only account for by the beds themselves varying considerably in short distances.