The Boulder Flatirons

September 05, 2019

2019 July 23 - a1  Boulder  Royal Arch Trail 2

2019 July 23 - a3  Boulder  Royal Arch Trail 13

2019 July 23 - a4  Boulder  Royal Arch  Cindy 2

Photographer: Cindy Todd
Summary Author: Cindy Todd 

The Royal Arch trail in Boulder, Colorado, winds upward through the Flatirons. This trail is hard, as it climbs over 1,400 feet (427 m), though the trail is only (5.1 km) round-trip. Fortunately, most of the trail is shaded as it winds through the forest going up and up. Along the way, you see numerous glimpses of the Flatiron formation for which Boulder is famous. At the end of this trail is a large arch which overlooks the Boulder area. On a clear day, Denver can be seen to the southeast.

The Flatirons are part of what’s called the Fountain Formation. This slanted, reddish-brown sandstone conspicuously juts out from the surface. Approximately 280 million years old, it formed after an ancestral Rocky Mountain range eroded. It seems that the Flatirons' initial position was a rather horizontal layer, but it became tilted as the current Rocky Mountain ranges were uplifted. Photo taken on July 23, 2019.

Photo Details: top - Camera: Canon PowerShot SX160 IS; Exposure Time: 0.0025s (1/400); Aperture: ƒ/4.0; ISO equivalent: 100; Focal Length: 8.9mm. Middle - same except: Exposure Time: 0.0020s (1/500); Focal Length: 6.0mm. Bottom - Same as top except: Exposure Time 0.0016s (1/640); Aperture: ƒ/3.5; ISO equivalent: 200; Focal Length: 5.0mm.