Flatirons Storm 60x20 from Sean Strait Photography.The Flatirons west of Boulder mark the transition from the grassland vegetation of the eastern plains to the ponderosa pine forests of the foothills.The Flatirons Vista Trail is among the 144 miles of trails covering 45,000 acres of preserved open space.Taken in late November 2011 as an approaching storm met the rising sunlight, capturing an extaordinary moment in an iconic Colorado setting.