And that reminds me of the time I was hiking the JMT just S of Reds Meadow. We erroneously followed a horse-made trail that wasn't on the map, where it exited the JMT near Red Cones. We came upon really old jmt trail markers, and then junctions that did not identify the JMT. Not knowing which trail to follow, I guessed (wrongly), and started off on a trail that curved around in the wrong direction. Here's the spot on the map. (small cross-hairs in the center)

I had my SPOT and cell service, so called my son in Michigan, who looked up my signal, told me where I was on the map, which got us going in the correct direction. I found the write-up from 2010: Lost on the JMT: Reds Meadow southbound

I suppose if I'd had a hand-held GPS unit with a map of the JMT, that would have helped me out, too. But not having those, and with the equipment we did have, we were back on track in a short time.