Robuta

https://conservancy.umn.edu/items/cbf7c6c3-ab90-4a9f-9a12-4af8ce73c61d RI-36 Paleozoic Lithostratigraphic Nomenclature for Minnesota Significant changes are made in stratigraphic nomenclature for the Paleozoic formations of Minnesota that reflect subsurface data acquired since 1969 and... ripaleozoicnomenclatureminnesota