Benchmarks, survey markers, and maps

[MojaveGeek]

I think you refer to the red markings of the PLSS, Public Land Survey System. It is/was a set of northing and easting coordinates based off one of several baselines, mostly San Bernadino in the Death Valley area, but maybe the Owlsheads are far enough south to be in a different one?

Anyway, it is rather arcane, but if you google around for PLSS for a while you can learn to decode it. And there is some USGS ? site which can overlay the PLSS coordinate system. The red lines are "sections" which are divided into quarters, etc.