The Geologic Column (Period)

RECENT (Holocene)Epoch

11,477

end of last Ice Age; rise of human civilization

Pleistocene Epoch

16,000

Ice Age(s);mass extinctions;rise of man

Pilocene Epoch

17,000

peak of mammals;modern invertebrates

Miocene Epoch

23,000

rise of grazing mammals

Oligocene Epoch

30,000

primitive apes;whales;first modern mammals

Eocene Epoch

34,000

first horses

Paleocenne Epoch

35,000

early mammals become dominant ;rise of modern birds

Creataceous

36,000

mass extinctions (including dinosaurs),flowering plants appear

Jurassic

39,001

giant dinosaurs;early birds;first mammals

Triassic

39,002

first dinosaurs ; rise of mammal-like reptiles

Permian

39,150

modern insects ; reptiles spread ; evergreeens ; extinction of trilobites

Pennsylvania

39,300

Mississippian

39,500

amphibians spread;sharks and nbony fish; winged insects

Devonian

39,999

first amphibians; freshwater fish ; wingless insects

Silurian

40,009

land colonized by arthropods and plants

Ordovician

43,000

trilobites abundant ; vertebrates increase

Cambrian

46,000

sudden explosion of life ; trilobites dominant;rise of other marine invertebrates;some vertebrates