DESCRIPTION OF STRATIGRAPHIC UNITS

     This description generally lists individual stratigraphic units in order of increasing age
or from left to right as the map units appear in the correlation diagrams. Stratigraphic units may
be included in one or more map units; such stratigraphic units are represented by the colors and
letter symbols in the boxes below and by the letter symbols in the correlation diagrams and list of
map units. Letter symbols following the description indicate which combinations have been made
because of cartographic limitations. The list of map units shows all the combinations of
stratigraphic units.
     System and series designations are given in the individual stratigraphic descriptions only
where the brackets beside the boxes do not indicate the specific age of the unit.  Ages are given
in Ma, Mega-annum (million years).