Paleontology and geology

Precambrian rocks occur in many parts of Idaho, the oldest of which occur in the south-central part of the state. These rocks are metamorphic and 2.5 to 2.7 billion years old. Precambrian glacial deposits occur in southeastern Idaho, and slightly to moderately metamorphosed sediments can be seen in northernmost Idaho (and adjacent Montana and Canada. The only known Precambrian fossils in the state are stromatolites from these sediments, as well as possible trace fossils in southeastern Idaho.