Morrison Formation Geography

Map of Colorado Plateau 149 million years ago with Dinosaur National Monument
A map of the Colorado Plateau as it may have looked 149 million years ago during the Jurassic when the Morrison formation was deposited.

Dr. Ron Blakey, Professor Emeritus Northern Arizona University Geology


149 million years ago, when the Morrison Formation was deposited, the area that is now Dinosaur National Monument looked much different. Large rivers dominated the landscape, flowing from highlands in the south towards the north. A savannah type of environment surrounded the river courses, but instead of a grassland, these savannahs featured ferns and conifers. It was in this environment that dinosaurs like apatasaurus, diplodocus, and stegosaurus grazed while avoiding the predatory allosaurus.

Artisitic rendition of the Morrison environment
Artist rendition of how the Morrison Environment may have appeared.

Last updated: February 24, 2015

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