ammonites
Decorah Shale (Stictopora angularis zone) Bryozoans, Upper Mississippi Valley (Ordovician of the United States)

Where: Minnesota, Iowa, Wisconsin, Illinois (42.5° N, 91.3° W: paleocoordinates 20.6° S, 63.7° W)

• coordinate estimated from map

• basin-level geographic resolution

When: Stictoporella angularis zone, Decorah Shale Formation, Rocklandian (460.9 - 449.5 Ma)

• formation-level stratigraphic resolution

Environment/lithology: gray shale and limestone

• Environmental call by T. Hanson.
• 40-50 feet thick. "[G]reenish-gray or olive-green, fissile, commonly blocky, fossiliferous shale interbedded with scattered and locally discontinuous, thin limestone beds."

Size class: macrofossils

Primary reference: O. L. Karklins. 1987. Bryozoa from Rocklandian (Middle Ordovician) rocks of the Upper Mississippi Valley region. Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley: Minnesota Geological Survey Report of Investigations 35 173-176 [S. Holland/T. Hanson/T. Hanson] more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 23309: authorized by Steven Holland, entered by Tori Hanson on 11.07.2002