The Precambrian in Iowa, US

Paleontology and geology

A small amount of Precambrian rock is exposed in the northwest corner of Iowa in Gitchie Manitou State Preserve. These reddish-colored rocks are the1.6-billion-year-old Sioux Quartzite, a metamorphic rock formed from nearly pure quartz sandstone. Other Precambrian-age rocks elsewhere across the state lie deeply buried beneath thousands of feet of sedimentary rocks. No fossils are known from these Precambrian rocks.