Paleontology and geologyA shallow sea flooded what is now Iowa during Late Cambrian time. The layers of sedimentary rock of this age represent deposition along shoreline, shallow marine shelf, and offshore shelf environments. Cambrian rocks are exposed best in far northeastern Iowa, in a topographic region called the Paleozoic Plateau. Although not abundant, fossils of inarticulate brachiopods, trilobites, algae, and burrows of wormlike organisms have been found in some of the state’s Cambrian rocks. |