For the more information about the geologic resources of the National Park Service, please visit http://www.nature.nps.gov/geology/.


Fossil Parks Through Geologic Time

Fossilized fern
Fossil Butte National Monument, WY.

The Geologic Time Scale is a way of organizing Earth's 4.5 billion-year history. The time scale is divided into four large periods of time—the Precambrian, Paleozoic Era, Mesozoic Era, and Cenozoic Era. National parks preserve fossils from each of these time blocks.

The Precambrian (prior to 542 million years ago) was the "Age of Early Life." Soft-bodied creatures like worms and jellyfish lived in the world's oceans. The land remained barren. Common Precambrian fossils include mats of algae called stromatolites, microorganisms, and simple animals. These parks, and several others, preserve Precambrian fossils:

Boston Harbor Islands National Recreation Area, MA
Death Valley National Park, CA & NV
Glacier National Park, MT
Grand Canyon National Park, AZ
Mojave National Preserve, CA
Yukon-Charley Rivers National Preserve, AK

The Paleozoic Era (542 to 251 million years ago) was the "Age of Fishes." Fish diversified and marine organisms were very abundant. Common Paleozoic fossils include trilobites and cephalopods such as squid, as well as insects and ferns. The greatest mass extinction in Earth's history ended this era. Paleozoic fossils have been discovered these parks and several others:

Bighorn Canyon National Recreation Area, MT & WY
Buffalo National River, AR
Carlsbad Caverns National Park, NM
Chickasaw National Recreation Area, OK
Coronado National Memorial, AZ
Cuyahoga Valley National Park, OH
Death Valley National Park, CA & NV
Delaware Water Gap National Recreation Area, NJ & PA
Denali National Park and Preserve, AK
Effigy Mounds National Monument, IA
Gates of the Arctic National Park and Preserve, AK
Glen Canyon National Recreation Area, AZ & UT
Grand Canyon National Park, AZ
Grand Teton National Park, WY
Guadalupe Mountains National Park, TX
Kobuk Valley National Park, AK
Lake Clark National Park and Preserve, AK
Mammoth Cave National Park, KY
Mississippi National River and Recreation Area, MN
Mojave National Preserve, CA
Natchez Trace Parkway, AL, MS & TN
National Capital Parks DC, MD, VA
Natural Bridges National Monument, UT
New River Gorge National River, WV
Oregon Caves National Monument, OR
Pictured Rocks National Lakeshore, MI
Russel Cave National Monument, AL
Saguaro National Park, AZ
Tallgrass Prairie National Preserve, KS
Timpanogos Cave National Monument, UT
Valley Forge National Historical Park, PA
Wind Cave National Park, SD
Wupatki National Monument, AZ
Yellowstone National Park, ID, MT & WY
Yukon-Charley Rivers National Preserve, AK

The Mesozoic Era (251 to 65.5 million years ago) was the "Age of Reptiles." Dinosaurs, crocodiles, and pterosaurs ruled the land and air. As climate changed, sea levels rose world-wide and seas expanded across the center of North America. Large marine reptiles such as plesiosaurs, along with the coiled-shell ammonites, flourished in these seas. Common Mesozoic fossils include dinosaur bones and teeth, and diverse plant fossils. These parks, and several others, preserve Mesozoic fossils:

Amistad National Recreation Area, TX
Aniakchak National Monument and Preserve, AK
Badlands National Park, SD
Big Bend National Park, TX
Bighorn Canyon National Recreation Area, MT & WY
Black Canyon of the Gunnison National Park, CO
Bryce Canyon National Park, UT
Cabrillo National Monument, CA
Canyonlands National Park, UT
Capitol Reef National Park, UT
Chaco Culture National Historical Park, NM
Denali National Park and Preserve, AK
Dinosaur National Monument, CO & UT
Gates of the Arctic National Park and Preserve, AK
Glacier National Park, MT
Glen Canyon National Recreation Area, AZ & UT
Golden Gate National Recreation Area, CA
Grand Canyon National Park, AZ
Grand Teton National Park, WY
Katmai National Park and Preserve, AK
Kobuk Valley National Park, AK
Lake Clark National Park and Preserve, AK
Mesa Verde National Park, CO
Natchez Trace Parkway, AL, MS & TN
National Capital Parks DC, MD, VA
Natural Bridges National Monument, UT
Oregon Caves National Monument, OR
Petrified Forest National Park, AZ
Prince William Forest Park, VA
Santa Monica Mountains National Recreation Area, CA
Springfield Armory National Historic Site, MA
Wind Cave National Park, SD
Wupatki National Monument, AZ
Yellowstone National Park, ID, MT & WY
Yukon-Charley Rivers National Preserve, AK
Zion National Park, UT

The Cenozoic Era (65.5 million years ago through today) is the "Age of Mammals." Birds and mammals rose in prominence after the extinction of giant reptiles. Common Cenozoic fossils include cat-like carnivores and early horses, as well as ice age fossils like wooly mammoths. Caves can preserve the remains of ice-age animals that died in them or were transported there after death. These parks, and and many more, preserve Cenozoic fossils:

Agate Fossil Beds National Monument, NE
Badlands National Park, SD
Bering Land Bridge National Preserve, AK
Boston Harbor Islands National Recreation Area, MA
Bryce Canyon National Park, UT
Buffalo National River, AR
Cape Krusenstern National Monument, AK
Carlsbad Caverns National Park, NM
Chaco Culture National Historical Park, NM
Channel Islands National Park, CA
Craters of the Moon National Monument and Preserve, ID
Cumberland Island National Seashore, GA
Death Valley National Park, CA & NV
Denali National Park and Preserve, AK
Florissant Fossil Beds National Monument, CO
Fossil Butte National Monument, WY
Gates of the Arctic National Park and Preserve, AK
Glacier National Park, MT
Glen Canyon National Recreation Area, AZ & UT
Golden Gate National Recreation Area, CA
Grand Canyon National Park, AZ
Grand Teton National Park, WY
Guadalupe Mountains National Park, TX
Hagerman Fossil Beds National Monument, ID
John Day Fossil Beds National Monument, OR
Katmai National Park and Preserve, AK
Kobuk Valley National Park, AK
Lake Clark National Park and Preserve, AK
Mammoth Cave National Park, KY
Mesa Verde National Park, CO
Mississippi National River and Recreation Area, MN
Mojave National Preserve, CA
Montezuma Castle National Monument, AZ
Natchez Trace Parkway, AL, MS & TN
National Capital Parks DC, MD, VA
Natural Bridges National Monument, UT
Niobrara National Scenic River, NE
Olympic National Park, WA
Oregon Caves National Monument, OR
Pinnacles National Monument, CA
Point Reyes National Seashore, CA
Russel Cave National Monument, AL
Saguaro National Park, AZ
Santa Monica Mountains National Recreation Area, CA
Scotts Bluff National Monument, NE
Theodore Roosevelt National Park, ND
Timpanogos Cave National Monument, UT
Tuzigoot National Monument, AZ
Valley Forge National Historical Park, PA
Vicksburg National Military Park, MS
War In The Pacific National Historical Park, Guam
Wind Cave National Park, SD
Wupatki National Monument, AZ
Yellowstone National Park, ID, MT & WY
Yukon-Charley Rivers National Preserve, AK
Zion National Park, UT

Geologic Time Scale

Geologic Time Scale

Geologic timescale created by Trista Thornberry-Ehrlich (Colorado State University). Major life history and tectonic events occurring on the North American continent are included. Red lines indicate major unconformities between eras. Boundary ages shown are in millions of years (Ma). Compass directions in parentheses indicate the regional location of individual geologic events. Adapted from the U.S. Geological Survey's Fact Sheet 2007-3015, with additional information from the International Commission on Stratigraphy.

Last Updated: December 02, 2013