Northwest USA
Physiographic Regions & Fossils

Columbia Plateau Rocky Mountains Great Plains Cascade–Sierra Mountains Pacific Border Basin & Range
Major physiographic regions of the American Northwest

Fossil Highlights

The American Northwest has a big record of fossils, from Cambrian trilobite to Ice‑Age megafauna. Below are the key periods/epochs and a single “mascot fossil” I picked for each area..

  • Columbia Plateau – Miocene–Pliocene flood‑basalt interbeds yield Oreodont skulls and petrified wood.
  • Rocky Mountains – The classic Cretaceous dinosaur: Triceratopscan be found here! Also home to the Hell Creek Formation (also in the Dakotas)
  • Great Plains – Paleocene–Eocene badlands with brontothere & early horse fossils; Brontotherium.
  • Cascade–Sierra Mountains – Oligocene–Miocene volcanic ash layers trap lush plants; and various leaves such as: Metasequoia.
  • Pacific Border – Rich Eocene marine mollusk faunas; giant scallop Patinopecten.
  • Basin & Range – Cambrian once-present ocean packed with trilobites: Olenellus.

To get more details info & maps, please visit the site right here -> https://earthathome.org/hoe/

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