GEOLOGY

Detailed explanation-1: -Devonian rocks of Ohio are world famous for their abundant and well-preserved trilobites. The best known Devonian trilobite, and probably the best known Ohio trilobite, is Phacops rana. From the 1920’s to the 1970’s, specimens of this species were collected by the thousands from a quarry near Sylvania, west of Toledo.

Detailed explanation-2: -Ohio is a great state for viewing and collecting fossils. All of the state’s bedrock (consolidated rock underlying soil and till) exposed at the Earth’s surface is sedimentary rock, and most of it contains fossils. Some rocks, such as many Ordovician-age limestones of southwest Ohio, are primarily composed of fossils.

Detailed explanation-3: -No Precambrian fossils are known from Ohio, so the state’s fossils record does not start until the Cambrian Period. During the later part of the period, Ohio was covered in seawater and located 10 degrees south of the equator. By the end of the Cambrian the sea was shallow and the climate dry.

Detailed explanation-4: -trilobite, any member of a group of extinct fossil arthropods easily recognized by their distinctive three-lobed, three-segmented form. Trilobites, exclusively marine animals, first appeared at the beginning of the Cambrian Period, about 542 million years ago, when they dominated the seas.