Reference definitions for terms used across site records: geologic time, managing agency types, archaeological culture designations, and the Indigenous nations named in each site's native lands documentation. See About for sourcing standards.
Geologic time
Precambrianbefore 538.8 Mya
Informal term for all geologic time before the Cambrian Period, encompassing the Archean and Proterozoic eons and roughly seven-eighths of Earth's history.
Archean4,031-2,500 Mya
Eon when Earth's crust first solidified into stable continental cores and the earliest confirmed life appeared.
Proterozoic2,500-538.8 Mya
Eon spanning the rise of atmospheric oxygen and the first complex, multicellular life.
Paleoproterozoic2,500-1,600 Mya
Earliest era of the Proterozoic eon.
Rhyacian2,300-2,050 Mya
Period within the Paleoproterozoic era.
Neoproterozoic~1,000-538.8 Mya
Latest era of the Proterozoic, ending with the first Ediacaran animals.
Paleozoic538.8-251.9 Mya
Era of early complex life, from the Cambrian Explosion to the end-Permian mass extinction.
Cambrian538.8-486.85 Mya
Period of the Cambrian Explosion, the rapid diversification of animal life.
Furongian~497-486.85 Mya
Final epoch of the Cambrian Period.
Ordovician486.85-443.1 Mya
Period ending in a mass extinction tied to continental glaciation.
Cincinnatian~458-443 Mya, approx.
Regional North American series for Late Ordovician rock of the Cincinnati Arch, source of the region's abundant marine fossils.
Silurian443.1-419.62 Mya
Period marking the diversification of early land plants and jawed fish.
Llandovery443.1-433.4 Mya
Earliest series of the Silurian.
Wenlock (Wenlockian)433.4-427.4 Mya
Middle series of the Silurian.
Ludlow (Ludlovian)427.4-419.62 Mya
Late series of the Silurian.
Devonian419.62-358.86 Mya
The "Age of Fishes," when the first forests and four-limbed vertebrates appeared.
Eifelian393.47-387.95 Mya
Middle Devonian stage.
Givetian387.95-382.31 Mya
Middle Devonian stage.
Frasnian382.31-372.15 Mya
Late Devonian stage, ending in a major mass extinction.
Famennian372.15-358.86 Mya
Final Devonian stage.
Carboniferous358.86-298.9 Mya
International term combining the Mississippian and Pennsylvanian subperiods, named for its extensive coal beds.
Mississippian358.86-323.4 Mya
North American subperiod of the early Carboniferous, named for exposures along the upper Mississippi River valley.
Kinderhookian~358.86-349 Mya, approx.
Earliest Mississippian regional series in North America.
Osagean~349-340 Mya, approx.
Mississippian regional series in North America.
Meramecian~340-330 Mya, approx.
Mississippian regional series in North America.
Pennsylvanian323.4-298.9 Mya
North American subperiod of the late Carboniferous, named for the state's coal-bearing strata.
Morrowan~323-318 Mya, approx.
Earliest Pennsylvanian regional series in North America.
Desmoinesian~314-305 Mya, approx.
Middle Pennsylvanian regional series, named for the Des Moines River valley.
Permian298.9-251.9 Mya
Final Paleozoic period, ending in Earth's most severe mass extinction.
Leonardian~290-280 Mya, approx.
Early Permian regional series in the south-central United States.
Mesozoic251.9-66 Mya
The age of dinosaurs, from the Triassic through the end-Cretaceous extinction.
Triassic251.9-201.4 Mya
Period following the end-Permian extinction, when dinosaurs first appeared.
Carnian~237-227.3 Mya
Late Triassic stage.
Norian~227.3-205.7 Mya
Late Triassic stage.
Jurassic201.4-145 Mya
Period of dinosaur dominance and the first birds.
Cretaceous145-66 Mya
Final Mesozoic period, ending with the asteroid impact that killed the non-avian dinosaurs.
Campanian83.6-72.2 Mya
Late Cretaceous stage.
Cenozoic66 Mya-present
Current era, following the extinction of the non-avian dinosaurs.
Paleocene66-56 Mya
Earliest Cenozoic epoch.
Eocene56-33.9 Mya
Epoch of a warm global climate and the diversification of modern mammal groups.
Oligocene33.9-23 Mya
Epoch of global cooling and grassland expansion.
Pliocene5.3-2.58 Mya
Epoch immediately preceding the Ice Ages.
Quaternary2.58 Mya-present
Current period, defined by repeated glacial cycles.
Pleistocene2.58 Mya-11,700 years ago
Epoch of the great Ice Age glaciations.
Illinoian~191,000-130,000 years ago
North American glacial stage, the "penultimate" glaciation before the Wisconsinan.
Wisconsinan~75,000-11,000 years ago
The most recent North American glaciation, which carved the Great Lakes and shaped much of the northern landscape.
Holocene11,700 years ago-present
Current epoch, beginning at the end of the last glaciation.
Meghalayan4,200 years ago-present
Current, most recent age of the Holocene.
Managing agencies
National Park Service (NPS)
Federal bureau within the Department of the Interior, established 1916, managing national parks, monuments, historic sites, and other units for both conservation and public use.
U.S. Fish & Wildlife Service (USFWS)
Federal bureau within the Department of the Interior managing the National Wildlife Refuge System along with endangered species and migratory bird protection.
U.S. Forest Service (USFS)
Federal agency within the Department of Agriculture managing National Forests and Grasslands under a multiple-use mandate for timber, recreation, watershed, and wildlife.
National monument
A federally protected area, often designated by presidential proclamation under the Antiquities Act (1906), to protect objects of historic, scientific, or scenic interest; may be managed by NPS, USFS, BLM, or USFWS depending on the site.
State park
Land managed by a state park agency for public recreation and resource conservation.
State wildlife area / State wildlife management area
Land managed by a state fish and wildlife agency primarily for habitat conservation and regulated hunting and fishing access.
State nature preserve
Land under state protection specifically for the conservation of rare or representative natural communities, typically with more restrictive use rules than a state park.
State historic site
Land managed by a state historical society or parks agency to preserve and interpret a specific historic or archaeological site.
State game area
Land managed by a state agency primarily for wildlife habitat and regulated hunting.
County park
Land owned and managed by a county government for local public recreation.
Municipal park
Land owned and managed by a city or township government for local public recreation.
Private preserve
Land owned and managed by a nonprofit conservation organization, such as a land trust, rather than a government agency.
Conservation district
Land managed by a local conservation district, a special-purpose government unit focused on natural resource management.
DOE legacy site
Land formerly used for U.S. Department of Energy nuclear weapons production or research, now managed under an environmental remediation and monitoring program.
Archaeological cultures
Adenac. 1000-500 BCE to c. 100-200 CE
Early Woodland moundbuilding culture of the Ohio Valley, known for conical burial mounds and effigy earthworks including part of Serpent Mound; not a single tribe.
Ancestral Puebloanc. AD 200-1300
Archaeological term for the farming and cliff-dwelling culture of the Four Corners region, ancestral to the modern Pueblo nations, Hopi, and Zuni.
Fort Ancient culturec. 1000-1650 CE
Late Prehistoric farming and village-building tradition of the Ohio, Kentucky, and Indiana river valleys, widely regarded as ancestral to the Shawnee.
Fremontc. AD 200-1300
Archaeological culture of the eastern Great Basin and Colorado Plateau, contemporary with the Ancestral Puebloans.
Hopewellc. 100 BCE-500 CE
Middle Woodland moundbuilding tradition centered on the Ohio Valley, known for its earthworks and the long-distance exchange network called the Hopewell Interaction Sphere; not a single tribe.
Paleoindianfrom c. 12,000 BCE
Archaeological term for the earliest documented human occupants of North America; not a tribe.
Indigenous nations
Apache
A group of related Athabaskan-speaking nations of the Southern Plains and Southwest, including the Jicarilla Apache of Colorado and New Mexico and the Fort Sill (Chiricahua) Apache of Oklahoma.
Apsáalooke (Crow)
Siouan-speaking nation of the Yellowstone and Bighorn river country in present Montana and Wyoming; the endonym means "children of the large-beaked bird."
Arapaho (Hinono’eino)
Algonquian-speaking Plains nation allied with the Cheyenne, historically ranging the Central and Northern Plains including the Bighorns and Colorado Front Range.
Atakapa-Ishak (Ishak)
Gulf Coast nation of southeast Texas and southwest Louisiana; the Akokisa were the nation’s eastern division.
Bannock (Bannakwut)
A Northern Paiute-speaking people of the Snake River Plain, closely allied with the Shoshone.
Báxoje (Ioway)
Siouan-speaking nation whose core territory spanned the Mississippi and Iowa River drainages.
Blackfeet (Niitsitapi)
Algonquian-speaking confederacy of the Northern Plains, ranging present Montana and southern Alberta.
Cherokee (Aniyvwiya / Tsalagi)
Iroquoian-speaking nation whose historic homeland spanned the Southern Appalachians; forcibly removed to Indian Territory on the 1838-39 Trail of Tears. The Eastern Band of Cherokee Indians remains on the Qualla Boundary in North Carolina.
Cheyenne (Tsitsistas/Suhtai)
Algonquian-speaking Plains nation, historically divided into Northern and Southern Cheyenne branches, closely allied with the Arapaho.
Chickasaw
Muskogean-speaking nation of the Mid-South, forcibly removed to Indian Territory in the 1830s.
Comanche (Nʉmʉnʉʉ)
Numic-speaking nation whose territory, the Comancheria, dominated the Southern Plains until forced onto reservations in 1874-75.
Cusabo (Escamacu)
A confederation of small coastal towns, including Kussoe, Edisto, Kiawah, and Etiwan, along South Carolina’s Sea Islands, largely dispersed by disease and Spanish and English contact in the 1600s.
Dakota
Eastern division of the Oceti Sakowin (Sioux), historically centered on Minnesota and the eastern Dakotas; the Sisseton, Wahpeton, Yankton, and Wahpekute are among its bands.
Delaware (Lenape)
Algonquian-speaking nation whose homeland, Lenapehoking, spanned the Delaware River valley before repeated removals pushed communities west through Ohio and Indiana to eventual settlement in Oklahoma and Kansas.
Eastern Shoshone
Numic-speaking nation of the Wind River and Green River country in present Wyoming, settled on the Wind River Reservation.
Erie (Eriehronon)
Iroquoian-speaking nation of the south shore of Lake Erie, dispersed by the Haudenosaunee during the Beaver Wars of the 1650s.
Hitchiti
A Muskogean-speaking, Hitchiti-language town group incorporated into the Muscogee (Creek) confederacy, with historic towns along the Ocmulgee River.
Ho-Chunk (Hochungra)
Siouan-speaking nation, "People of the Big Voice," of the Wisconsin, Iowa, and Illinois region, also historically called Winnebago.
Hopi (Hopisinom)
Puebloan nation of northeastern Arizona, descended in part from the Ancestral Puebloans.
Kickapoo
Algonquian-speaking nation historically of the Ohio-Wabash region, later removed to Kansas, Oklahoma, and Mexico.
Kiowa (Cáuigù)
Plains nation historically allied with the Comanche, with territory across the Southern Plains.
Lakota (Thítȟuŋwaŋ)
Western division of the Oceti Sakowin (Sioux), whose seven bands, including the Oglala, Sicangu, and Hunkpapa, ranged the Northern Plains including the Black Hills.
Meskwaki (Meshkwahkihaki)
Algonquian-speaking nation, "Red-Earths people," historically allied with the Sauk, with a present-day settlement in Tama County, Iowa.
Miami (Myaamiaki)
Algonquian-speaking nation whose core territory spanned the Wabash and Great Miami river valleys of Indiana and Ohio; also known by its own endonym, Myaamia.
Moneton
A little-documented Siouan-speaking nation known from pre-contact archaeological evidence along the New River in present West Virginia.
Muscogee (Creek/Mvskoke)
Muskogean-speaking confederacy of the Southeast whose towns anchored the Ocmulgee and Chattahoochee river valleys before removal to Indian Territory.
Navajo (Diné)
Athabaskan-speaking nation of the Four Corners region, the largest federally recognized tribe by land and population.
Niimíipuu (Nez Perce)
Sahaptian-speaking nation of the Columbia Plateau in present Idaho, Oregon, and Washington.
Oceti Sakowin (Sioux)
The "Seven Council Fires" confederacy of Dakota, Lakota, and Nakota bands whose territory spanned the Northern Plains including the Black Hills.
Ojibwe (Anishinaabe)
Algonquian-speaking nation of the western Great Lakes, part of the broader Anishinaabe alliance with the Odawa and Potawatomi known as the Council of Three Fires.
Osage (Wazhazhe)
Siouan-speaking nation whose ancestral domain spanned Missouri, Kansas, and Oklahoma.
Ottawa (Odawa)
Algonquian-speaking nation of the western Lake Erie shore, part of the Anishinaabe Council of Three Fires.
Potawatomi (Bodéwadmi)
Algonquian-speaking nation of the southern Great Lakes, the third member of the Anishinaabe Council of Three Fires.
Pueblos
Collective term for the Indigenous farming nations of the Rio Grande valley and adjacent New Mexico, descended from the Ancestral Puebloans.
Sauk (Ozaakiiwaki)
Algonquian-speaking nation historically allied with the Meskwaki (Fox), displaced from Illinois after the 1832 Black Hawk War.
Seneca (Onöndowa’ga:’)
Westernmost nation of the Haudenosaunee (Iroquois) Confederacy, with historic territory extending into Ohio and West Virginia.
Shawnee (Shawanwaki / Shawandasse Tula)
Algonquian-speaking nation whose historic range spanned the Ohio Valley, with no fixed capital and frequently relocated principal towns; forcibly removed to Kansas and Indian Territory in the 1830s.
Southern Paiute (Nuwuvi)
Numic-speaking nation of the Colorado Plateau in southern Utah, Nevada, and Arizona; the Kaibab Band of Paiute Indians is one of its descendant communities.
Tukudika (Mountain Shoshone)
A Shoshone band, the "Sheep Eaters," who lived year-round at high elevation in the Yellowstone Plateau.
Ute (Núuchi-u / Núu-agha-tʉvʉ-pʉ̱)
Numic-speaking nation of the Colorado Plateau and central Rockies, historically organized into bands including the Mouache, Weeminuche, and Uintah, today the Southern Ute, Ute Mountain Ute, and Ute Indian Tribes.
Wea
Algonquian-speaking nation closely related to the Miami, with a historic town at Ouiatenon on the Wabash River near present Lafayette, Indiana.
Wichita (Kitikiti’sh)
Caddoan-speaking nation whose ancestral territory centered on the confluence of the Arkansas and Little Arkansas Rivers in present Kansas, later removed to Indian Territory.
Wyandot (Wendat/Huron)
Iroquoian-speaking confederacy formed partly from Erie and Petun survivors after the Beaver Wars; the last Indigenous nation forcibly removed from Ohio, in 1843.
Yamasee
A coalescent Southeastern nation formed from refugees of the Spanish Guale and Mocama missions, driven from South Carolina after the Yamasee War of 1715-17.
Yuchi (Tsoyaha)
"Children of the Sun," a linguistically isolated nation of the Savannah River basin in Georgia and South Carolina, displaced westward by Creek and Carolina pressure in the early 1700s.
Zuni (A:shiwi)
Puebloan nation of west-central New Mexico, linguistically distinct from other Pueblo nations.