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The Iron Dike 
A Geologic Wonder of Colorado 
Outcrop of 1.3-billion-year-old
Iron Dike's dark gabbro on
Trail Ridge road.  Click to
enlarge image.
Iron Dike at Steep Mountain
Image: Stefan and Richard Hollos
Click to enlarge image
Iron Dike intrusion into nearby granite
Image: Stefan and Richard Hollos
Stefan Hollos shown.  Click to enlarge
Iron Dike on south side of
Steep Mountain - Image: Stefan
and Richard Hollos
Click to enlarge image
About 1.3 billion years ago, the crust was extended in a northeast-southwest direction.  Molten material intruded the older Precambrian igneous and metamorphic rocks forming dikes trending in a northwest-southeast direction.  Most of the dikes are dark igneous rocks such as gabbro.

A striking example of these dikes is the sixty-eight-mile-long Iron Dike, which intruded 1.3 billion years ago and extends from south of Boulder northeastward across Rocky Mountain National Park.

The distinctive gabbro of the Iron Dike along Trail Ridge Road in Rocky Mountain
National Park.  Image:  V. Matthews  Click image for enlarged close-up view

Last Updated: 1/24/2013 2:48 PM 
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