FOOTNOTES

1 Query indicates uncertainty of position of top of unit within the Pleistocene.
2 Age of upper parts of uppermost Miocene units is problematic.  These parts 
      have historically been assigned to the Pliocene.  Successive reduc-
      tions in radiometric age of the top of the Miocene in Europe to 7 Ma
      (Lambert, 1971) and to 5 Ma (Berggren, 1972) place a Pliocene age in
      question, although the top beds of the formations have not been dated.
3 Karlstrom and others (1983).
4 Divis (1976).
5 Houston and others (1968).
6 Snyder (1980).
7 McCallum (1968).