Template talk:Paleozoic Stratigraphy of the Upper Midwest

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Ages of Rock Units[edit]

There are two sources listed for this template but neither list the date ranges given for the ages of the rock units listed. Which sources were used? I know the lower age of the Decorah Shale is given as 454 ma which must be based on the Deicke K bentonite but there should be references for all dates. Kirkmona (talk) 14:50, 10 March 2009 (UTC)