The Four Mile Dam Formation, also called the Four Mile Dam Limestone, is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Michigan Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the middle

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, w ...

period.

An examination of the Devonian fishes of Michigan fig-1-full

Fossil content

Vertebrates

Acanthodians

Conodonts

Placoderms

Invertebrates

Brachiopods

Corals

Gastropods

Sponges

Trilobites

References

* Devonian Michigan Devonian southern paleotemperate deposits {{Michigan-geologic-formation-stub