Bedrock Geology of Cedar County, Iowa Final Phase: Bedrock Geologic Map of Cedar County 1:100,000

https://ir.uiowa.edu/igs_ofm/1060/thumbnail.jp

Geodes: A Look at Iowa\u27s State Rock

Iowa geodes have long been objects of curiosity, their sparkling interiors containing some of the most beautiful crystals to be found anywhere in the Midwest. Although geodes are known from many localities around the world, one of the most productive and famous collecting regions is encompassed within a 35-mile radius of Keokuk, Iowa. Rock collectors commonly refer to geodes from this region as Keokuk geodes. In keeping with the world-renowned status of the Iowa geodes, the Iowa General Assembly declared the geode as the official State Rock in 1967

Bedrock geology of southeast Iowa, Digital geologic map of Iowa, Phase 7: Southeast Iowa

https://ir.uiowa.edu/igs_ofm/1032/thumbnail.jp

Bedrock Geologic Map of Iowa

https://ir.uiowa.edu/igs_ofm/1070/thumbnail.jp

Bedrock geology of southwest Iowa, Digital geologic map of Iowa, Phase 5: Southwest Iowa

https://ir.uiowa.edu/igs_ofm/1028/thumbnail.jp

Bedrock geology of the quadrangles containing the Yellow River Basin, Allamakee, Clayton, Fayette, and Winneshiek counties, Iowa

https://ir.uiowa.edu/igs_ofm/1042/thumbnail.jp

Bedrock geology of east-central Iowa, Digital geologic map of Iowa, Phase 6: East-Central Iowa

https://ir.uiowa.edu/igs_ofm/1029/thumbnail.jp

Potential for Geologic Sequestration of CO2 in Iowa

https://ir.uiowa.edu/igs_tis/1056/thumbnail.jp

Bedrock geology of south-central Iowa, Digital geologic map of Iowa, Phase 4: South-Central Iowa

https://ir.uiowa.edu/igs_ofm/1024/thumbnail.jp

An Expanded Stratigraphic Record of the Devonian-Carboniferous Boundary Hangenberg Biogeochemical Event from Southeast Iowa (U.S.A.)

The Devonian-Carboniferous boundary in the type area of the Mississippian subsystem (tri-state area of Iowa, Illinois, and Missouri) has been historically difficult to identify. Many of the localities contain similar lithologies and stratigraphic successions, but chronostratigraphic correlation of seemingly identical lithologies can vary greatly in this interval and frequently this has led to miscorrelation. In particular, the similar lithofacies that comprise the McCraney Formation and Louisiana Formation have been a source of stratigraphic confusion for over 100 years. To investigate the Devonian-Carboniferous boundary interval in the Mississippian type area we selected two localities in southeastern Iowa, the H-28 core from Lee County outside of Keokuk, Iowa, and the Starr’s Cave outcrop located near Burlington, Iowa. In total, 62 conodont samples and 299 carbonate carbon isotope samples were processed for this study and recorded the Hangenberg positive carbon isotope excursion and 25 conodont species, including a diverse assemblage of siphonodellids. The Hangenberg excursion is recorded in over 20 m of strata in southeast Iowa, making this one of the thickest stratigraphic records of this important biogeochemical event yet recovered, and helps to define more clearly the position of the base of the Carboniferous System in the region. These results show that the “McCraney” Fm. at the Starr’s Cave outcrop and the coeval carbonate unit in the H-28 core are both the Louisiana Formation, and calls into question the use of the name McCraney throughout the State of Iowa