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Geologic units in Goodhue county, Minnesota

Upper and Middle Ordovician rocks, undivided (Late and Middle Ordovician) at surface, covers 59 % of this area

Upper and Middle Ordovician rocks, undivided - Limestone and shaly limestone of the Maquoketa and Dubuque Formations, and limestone and dolostone of the Galena Group in the Hollandale embayment of southeastern Minnesota

Decorah Shale (Middle Ordovician) (Middle Ordovician) at surface, covers 23 % of this area

Decorah Shale (Middle Ordovician) - Light-greenish-gray shale and lesser amounts of coquinoid limestone, especially in the upper half of the formation. Mapped as a separate unit where possible.

Lithology: shale; limestone

Lower Ordovician rocks, undivided (Lower Ordovician) at surface, covers 12 % of this area

Lower Ordovician rocks, undivided - Shakopee and Oneota Formations of the Prairie du Chien Group in the Hollandale embayment of southeastern Minnesota. Unit consists dominantly of dolostone and dolomitic limestone. The Shakopee also contains intervals of quartz arenite, including a pronounced basal unit named the New Richmond Member

Middle Ordovician rocks, undivided (Middle Ordovician) at surface, covers 6 % of this area

Middle Ordovician rocks, undivided - Decorah Shale; limestone of the Platteville Formation; shaly rocks of the Glenwood Formation; and St. Peter Sandstone in the Hollandale embayment of southeastern Minnesota

Lithology: sandstone; limestone; shale

Upper Cambrian, undivided (Late Cambrian) at surface, covers 0.1 % of this area

Upper Cambrian, undivided - Jordan Sandstone; dolomite, glauconite, and silty glauconite rocks of the St. Lawerence and Franconia Formation; Ironton and Galesville Sandstones; sandy and shaly rocks of the Eau Claire Formation; and the Mt. Simon Sandstone.