I had an opportunity today to spot one of the scenic sights of the Switzerland Trail between Wall Street and Sunset in Colorado. Given that I’m writing a historical mystery set along the Switzerland Trail railroad route in 1919, I like to find the places I’ll be writing about. The attached picture shows Copper Rock on the north side of Four Mile Creek. The railroad had a flag stop on the south side of the creek here. If you study the picture you’ll notice a swatch of bluish-green, a stain from corroded copper.