The Maquoketa Formation is a geologic formation in Illinois,[1] Indiana.

[2] Iowa, Kansas,[3] Minnesota,[4] Missouri,[5] and Wisconsin.

[6] It preserves mollusk, coral, brachiopod and graptolite fossils[5] dating back to the Darriwilian to Hirnantian stages (Edenian to Richmondian in the regional stratigraphy) of the Ordovician period.

[7] This article about a specific stratigraphic formation in the United States is a stub.

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