We spent the day at Arches National Park; after our exertions hiking out on the slickrock to see the Upheaval Dome area the day before, we were moving slower and somewhat painfully, so we took an “easy” day driving around part of the park and taking short spur hikes to see arches and interesting rocks. At one point we got into an area just off the road called “Sand Dune Arch” and luckily we had it to ourselves. It’s in an area of long, thin vertical fins of red sandstone, and there’s extremely fine red sand (or rock dust) underfoot.…