Michigan Geology

Just how old is Michigan?

Michigan has a long geologic history. The oldest rocks in the state are over 3.5 billion years old. The older rocks in the state host important deposits of iron and copper. Younger rocks (500-300 million years old) include sandstones and limestones. These rocks host oil and natural gas. Many of the state’s fossils are found in these sedimentary rocks. The youngest earth materials in Michigan are glacial sediments left behind as the massive ice sheets melted away after the last ice age.