Boulder's iconic Flatirons are named so for the home-style tools they resemble. These distinctly shaped rocks are remnants of the Fountain Formation, a feldspar-rich sand eroded from the ancestral Rocky Mountain uplift 300 million years ago. Sediments deposited by inland oceans compressed this layer into sandstone, thrust upward 45 million years ago by the same forces that created our modern Rocky Mountains. A short but challenging hike leads from Chautauqua Park to the backside with exceptional views across the Colorado Front Range and Continental Divide.

Golden Banner, a member of the pea family, is among the first flowers to bloom in Chautauqua Park

The oldest rocks in the Front Range are carbon dated at 1.7 billion years old, or simply "Precambrian"

The trail begins moderately in open space before steepening through rugged forest and scree fields to Flatiron #1

Red-tailed hawks are among the largest and most widely distributed hawks in North America

Boulder's Flatirons and Sanitas Ridge are both part of the Fountain Formation

Ponderosa forests depend on periodic, low-intensity fires to maintain proper tree densities and limit build up of fuel that can trigger more intense, destructive fires

The Front Range was flooded by a vast ocean around 600 million years ago at the beginning of the Paleozoic era

Wildflowers emerge in late June

Primary physical differences between mule deer and whitetail deer include the size of their ears, tail color, and antler growth patterns

Once uplifted, soft sediments of the Fountain Formation were shaped by wind, water and freeze-thaw cycles

High above Boulder, view of rock climbers resting after ascending up Flatiron #1's face

The Flatiron Loop offers a cross-section view of the formations' geological make up

Flatiron #3, seen from the Flatiron Loop