The Greenhorn Formation and Carlile Shale (Cenomanian and Turonian) crop out in western Minnesota near the town of Browns Valley. The locality (NE¼, NE¼, Sec. 2, T125N, R49W) provides important lithologic and biostratigraphic data because it is situated in an area of sparse outcrop. About 3 m of chalk and limestone are assigned to the Greenhorn; Mytiloides labiatus (Schlotheim) and Watinoceras coloradoense (Henderson) are present in the unit. The Carlile Shale is approximately 35 m thick and includes the Fairport, Blue Hill, Codell Sandstone, and upper unnamed members. Collignoniceras woollgari (Mantel) is present in the Blue Hill Member.

The Greenhorn Formation and Carlile Shale were deposited in shallow marine environments on the eastern margin of the Late Cretaceous seaway. Postdepositional tectonism is suggested by an observed dip of 27°. The units are potential shallow, low-permeability gas reservoirs.

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