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Ancestral Rockies
300 million years ago (Pennsylvanian)

Find the clickable hot spots for details and evidence, or follow the links below. (Click to see larger image)

This is an utterly strange Colorado, where millipedes are as big as snowboards and dinosaurs haven’t yet evolved. Colorado has mountains, but it also has coastlines on its eastern and western borders. The mountains are part of a range that extends southeast to what is now Arkansas. The surrounding confier forests are relatively new to the planet. Gravelly streams wind their way through forests of 100-foot-tall scale trees and giant relatives of the horsetail rush (Calamites). Buzzing insects such as dragonflies are huge, but fin-backed protomammals, reptiles, and amphibians are relatively small.

Artist: Jan Vriesen

Formation: Fountain

Best Viewing Spots:

  • Garden of the Gods Park and Visitor Center
  • Roxborough State Park
  • Red Rocks Park and Amphitheatre
  • Boulder Flatirons
Roxborough State Park
Roxborough State Park is a place where the Fountain Formation has been tipped up and exposed.

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