Editing Front Range (section)

===Fountain formation===
Around 300 million years ago, the sinking suddenly reversed, and the sediment-covered granite began to [[Orogeny|uplift]], giving rise to the [[Ancestral Rocky Mountains]]. Over the next 150 million years, during the uplift the mountains continued to erode and cover their flanks in their own sediment. Wind, gravity, rainwater, snow, and ice-melt supplied rivers that ultimately carved through the granite mountains and eventually led to their complete removal. The sediment from these mountains lies in the very red [[Fountain Formation]] today. [[Red Rocks Amphitheatre]] outside of Denver, Colorado, is set within the Fountain Formation.<ref name="ancientdenvers" />