These giant, Pennsylvanian red sandstone slabs rise as a dramatic backdrop
to south Boulder and are the town's best-known geological landmarks.
The alluvial deposits thrust upward into jagged peaks almost 70 million years ago,
during the birth of the Rocky Mountains.
Today, residents and visitors alike enjoy hiking around the base
and climbing the front face of The Flatirons.
Towering 1400 feet above Boulder, the Third Flatiron is one of the most popular climbing routes in North America.