The technical explanation is that the red rocks were made by layers of sand, calcite, and iron oxide that collected in prehistoric seas around fossilized matter. Supposedly because the bedrock is close to the surface in this area, the erosion revealed these boulders along with some other badlands topography. All of this is well and good, but mostly I was just focused on climbing around on them.
As is usually the case, I snapped a bunch of pictures of our brief adventure. The red rocks were still warm from the heat of the day, and as the sun set the landscape really made a strong impression. The clouds were streaked across the sky, the golden sunset brought out the natural colours in the rock, and there we were, both pretty content that we'd timed our arrival so well.