Natural History

Brule Formation

The Brule Formation is a sequence of fine grained clastic rocks (claystones, mudstones, siltstones) interbedded with freshwater carbonates, volcanic ash (tuff), and sandstonein South Dakota, Nebraska, Colorado, North Dakota, and Wyoming. It was deposited between 34 and 30 million years ago, roughly the Rupelian age (Oligocene). It occurs as a subunit of the White River Group.

Also on this shelf

See also

• ▸Crooked River State Park
• ▸Achille Castiglioni
• ▸Bachman's sparrow

Uncatalogued shelf

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