Both the wire and the pipe fittings look old and rusty. There's no sign of insulators so I wouldn't think this setup would've been designed for any electrical or communications use -- not directly, anyway. Someone obviously went to a certain amount of trouble to put it there, so what could it be for? One possibility that occurs to me, is that it might have been the "messenger wire" mechanically supporting something like a telephone cable that's no longer there.
Here's a pic from Columbia Rock showing the location of the pipe-supporting rock. It was cropped from a much wider view so it's not very sharp, unfortunately:
Last September I was up at Columbia Rock again and happened to catch the light just right. Here's the same rock and the wire shining in the sun:
This xRez view from Eagle Point (with my labels added) shows the rock and both of the switchbacks in question:
[Picture corrected 5/28/14. The previous version had the "L28" switchback label a little too low, at L26.]
In case anyone's not familiar with xRez, here's where that pic came from... http://www.xrez.com/yose_proj/yose_deepzoom/index.html ... and here's some more about it: http://www.xrez.com/case-studies/national-parks/yosemite-extreme-panoramic-imaging-project/
Edited 1 time(s). Last edit at 05/28/2014 10:47AM by gophersnake.