This image of the milky way and the rock art was taken just past true night, when the sun is less than 18degrees below the horizon. Hence the bluish sky, which is due to the phenomena Rayleigh Scattering which is the scattering of sunlight via particles in the atmosphere. This does not occur during true night.

However in this early stage of twilight many of the details the milky way are still visible, note the Dark Horse Nebula and the Rho Ophiuchi star complex which is seen by following one of the horse's long legs to the to the star cluster.

All illumination on the petroglyphs is a mixture of weak sunlight and starlight.

Nikon D810a
Samyang 14mm f/2.8
30s
ISO 3200

20 sequential photos were taken at ~5:20am. All 20 photos were aligned for the purpose of noise reduction using the program Starry Landscape Stacker. This produces a single noise reduced TIFF Image file. This file was then imported into Photoshop where adjustments were made to both the land and sky via the curves tool.