So I followed that side drainage up and east of the main wash and found a large piece of a weathered milled wood beam which told me I was hot onto something.
Sure enough, several hundred yards up that side ravine was an old cabin site but with little remaining. Wondering why this site was chosen, I scampered up the increasingly steep ravine which was decorated with gorgeous red stone and a few narrows, but I never saw any sign of human activity or mining. I surmised that the old cabin site was a layover for travelers heading up the canyon to the mines there.
I eventually topped out over the ridge and followed its snaking spine north with view 360 and down into Virgin Spring Canyon. I wisely turned back to the car instead of punishing my knees and feet with miles of additional hiking up and around. Like Arnold, "I'll be back."