I painted this from a photo I took in a Juniper wilderness area east of Bend. It's a wonderful, unimproved area called the Badlands.
I was trying a suggestion I read in Terry Miura's blog which was to start with a gray mixed from cad yellow, cad red and ultramarine. Mix it with white to get four graduated values, then start your color mix with the appropriate value of gray.
My gray was kind of green although I tried to make to make it less so. I'm going to continue working with this concept for a while.