Figure 3. Chronostratigraphic column for the Colville basin, northern Alaska, showing revised stratigraphic nomenclature and ages of units discussed in this paper (in color); laterally correlative and overlying and underlying units not discussed in this paper are uncolored in diagram. Abbreviations or symbols are as follows: <?>, uncertain relationship; cs*, cobblestone sandstone of Fortress Mountain Formation (informal unit of Mull and others, 2003); ms**, manganiferous shale unit (informal term); Kemik***, Kemik Sandstone (formation) as revised by Molenaar and others (1987); Fm., Formation; Mtn., Mountain; LCU, Lower Cretaceous unconformity. Geologic time scale from Gradstein and Ogg (1996).
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