The Front Range runs north-south between Casper, Wyoming, and Pueblo, Colorado, and rises nearly 10,000 feet above the Great Plains.

The area is a popular destination for mountain biking, hiking, climbing, and camping during the warmer months and for skiing and snowboarding during winter.

About 1 billion years ago, a mass of magma rose to the surface through a much older mantle, cooling to form what is now known as the Precambrian Pikes Peak Granite.

[2][3] Around 300 million years ago, the sinking suddenly reversed, and the sediment-covered granite began to uplift, giving rise to the Ancestral Rocky Mountains.

Wind, gravity, rainwater, snow, and ice-melt supplied rivers that ultimately carved through the granite mountains and eventually led to their complete removal.

This formation can be best attributed to its wavy layers of muddy limestone and signs of stromatolites that thrived in a tidal flat in present-day Colorado.

[2] The Dakota Sandstone, which was deposited around 100 million years ago at the opening of the Cretaceous Western Interior Seaway from the Arctic to the Tropics, shows evidence of ferns and dinosaur tracks.

At about 68 million years ago, the Front Range began to rise again due to the Laramide Orogeny in the western half of the state, draining from being at the bottom of a sea to land again, giving yield to another fossiliferous rock layer, the Denver Formation.

While this extinction led to the demise of the dinosaurs and other organisms, some life did prevail to repopulate the earth as it recovered from this tremendous disaster.

However, as seen before, life rebounds, and after a few million years mass floods cut through the rhyolite and eroded much of it as plants and animals began to recolonize the landscape.

[2] Eventually, at about 10 million years ago, the Front Range began to rise up again and the resistant granite in the heart of the mountains thrust upwards and stood tall, while the weaker sediments deposited above it eroded away.

Originally the Denver and Salt Lake Railway, the former Rio Grande is used for freight by both Union Pacific and BNSF, and it is also used by Amtrak's California Zephyr and Winter Park Express.