Part 1; using css: geologic time is divided into eras, periods, and epochs. the eras and their periods are: proterozoic: (none) paleozoic: cambrian, ordovician, silurian, devonian, mississippian, pennsylvanian, and permian mesozoic: triassic, jurassic, and cretaceous. cenozoic: paleogene and neogene. only the paleogene and neogene periods are divided into epochs. they are: paleogene: paleocene, eocene, and oligocene neogene: miocene, plioce