One thing I noticed taking photos in Grand Canyon Nat. Park back in early spring 2014—first time there not using film—was that the tonality was unusual. Not to my eyes but to my gear. The camera I was using, an Oly EM-1, picked up a lot of UV. Not being a big filter guy I didn't have any UV filters with me, so I had to wing it in post with not-subtle white balance and tint adjustments.
-Dave-