[whiddershins]

The man is digging post holes, which means he is putting up a fence.

By putting up a fence he alters so many things about the land, in a profound way, and the others who occupy that land have a relationship and reaction to this fence.

Edit: maybe it isn’t a fence. Could be set up for a railway? Or something else like early poles for wires for communication?

I’ve read a lot of McCarthy but not Blood Meridian