Evidence:

• Years Ago: 3.6 million years ago

• Geologic Timescale: Cenozoic Era, Pliocene Epoch

Evidence of the asteroid impact that led to the mass extinction of dinosaurs, forming this massive crater.

Evidence:

• Years Ago: 66 million years ago

• Geologic Timescale: Cenozoic Era, Paleogene Period, Paleocene Epoch

The cave system provides evidence of past climate and environmental conditions, including when North America was much wetter.

Evidence:

• Years Ago: Ongoing formation over millions of years, with significant activity during the Pleistocene

• Geologic Timescale: Cenozoic Era, Quaternary Period, Pleistocene Epoch

This site could be one of the earliest human-made places of worship, dating back to the Pre-Pottery Neolithic period.

Evidence:

• Years Ago: 11,600 - 13,200 years ago

• Geologic Timescale: Cenozoic Era, Holocene Epoch

One of the richest dinosaur fossil localities, providing evidence of numerous species.

Evidence:

• Years Ago: 75 million years ago

• Geologic Timescale: Mesozoic Era, Cretaceous Period

The remains of a huge impact crater, one of the oldest and largest known.

Evidence:

• Years Ago: 214 million years ago

• Geologic Timescale: Mesozoic Era, Triassic Period

Known for its vast deposits of dinosaur bones, including iconic species like Stegosaurus.

Evidence:

• Years Ago: 150 million years ago

• Geologic Timescale: Mesozoic Era, Jurassic Period

Massive volcanic eruptions that might have contributed to the end of the Cretaceous extinction event.

Evidence:

• Years Ago: 66 million years ago

• Geologic Timescale: Mesozoic Era, Cretaceous Period

Rich in fossils from the Cambrian explosion, showing a rapid diversification of life forms.

Evidence:

• Years Ago: 508 million years ago

• Geologic Timescale: Paleozoic Era, Cambrian Period

Evidence of one of the oldest coral reef systems, indicating past marine environments.

Evidence:

• Years Ago: 400 million years ago

• Geologic Timescale: Paleozoic Era, Devonian Period

Fossilized trees and other plant life from the Carboniferous period when coal swamps covered the area.

Evidence:

• Years Ago: 310 million years ago

• Geologic Timescale: Paleozoic Era, Carboniferous Period

Layers showing the Permian mass extinction, one of the most severe in Earth's history.

Evidence:

• Years Ago: 252 million years ago

• Geologic Timescale: Paleozoic Era, Permian Period

Contains some of the oldest known rocks on Earth, providing insights into early Earth's geology.

Evidence:

• : 3.5 billion years ago

• Geologic Timescale: Precambrian, Archean Eon
  

Early evidence of microbial life with preserved isotopic signatures.

Evidence:

• Years Ago: 3.8 billion years ago

• Geologic Timescale: Precambrian, Archean Eon

Stromatolites here are among the oldest known fossils, indicating early life forms.

Evidence:

• Years Ago: 3.4 billion years ago

• Geologic Timescale: Precambrian, Archean Eon

Contains minerals that suggest the presence of water and possibly life very early in Earth's history.

Evidence:

• Years Ago: 4.28 billion years ago

• Geologic Timescale: Precambrian, Hadean Eon