National Park Service Paleontology Program

Move your cursor over the time period you wish to know more about. Click on the period name or the accompanying images to visit a National Park with features of that age.

Visit the Bering Land Bridge National Preserve Geology Page

Visit the Hagerman Fossil Beds National Monument Geology Page

Visit the Agate Fossil Beds National Monument Geology Page

Visit the Badlands National Park Geology Page

Visit the Fossil Butte National Monument Geology Page

Visit the Theodore Roosevelt National Park Geology Page

Visit the Big Bend National Park Geology Page

Visit the Dinosaur National Monument Geology Page Geology Page

Visit the Petrified Forest National Park Geology Page

Visit the Guadalupe National Park Geology Page

Visit the Grand Canyon National Park Geology Page

Visit the New River Gorge National River Geology Page

Visit the Death Valley National Park Geology Page

Visit the Delaware Water Gap National Recreation Area Geology Page

Visit the Yellowstone National Park Geology Page

Visit the Glacier National Park Geology Page

Geologic Time Scale

Quaternary

Modern humans appear

Present - 2 million years ago

Abundant mammals

2 - 65 million years ago

Cretaceous	Flowering plants; dinosaur & ammoid extinctions	65-140 million years ago
Jurassic	First birds & mammals; abundant dinosaurs	140-205 million years ago
Triassic	Abundant coniferous trees	205 - 245 million years ago

Permian	Extinction of trilobites & other marine animals	245 - 290 million years ago
Pennsylvanian	Fern forests; abundant insects; first reptiles	290 - 325 million years ago
Mississippian	Sharks; large primitive trees	325 - 355 million years ago
Devonian	Amphibians & ammonoids	355 - 415 million years ago
Silurian	Early plants & animals on land	415 - 440 million years ago
Ordovician	First fish	440 - 495 million years ago
Cambrian	Abundant marine invertebrates; trilobites dominant	495 - 545 million years ago

	Proterozoic	Primitive aquatic plants	545 - 2500 million years ago
	Achean	Oldest fossils: bacteria & algae	2500 - 3800? million years ago

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