West of the Eroding Rubble
I've stared out my front door at this monolith for years and figured it was high time to try and stand atop it. I was unable to find any beta on the hike, so I went in somewhat blind, unsure if it was even possible to summit without climbing gear (spoiler alert: it is, though it does require 5th class moves and some blood letting).
This summit is no joke. Reaching the top requires 5th Class (i.e. rock climbing) moves with exposure where a slip could result in serious injury or death. The approach offers no shade or water and is definitely not recommended in the summer. Using a GPS is highly recommended to take advantage of the faint trail that exists for the first 1.5 miles of the approach. The trip time, distance, and elevation gain listed here are all approximate given that I did a bit of wandering along the way.
This route is a continuation of the Campbell Cliffs hike (though it could also be accessed from Pima Canyon following the description for Prominent Point or Rosewood Saddle). Follow the well-cairned trail through the easement, into the National Forest land, up the steep hillside, along the Rosewood Saddle (with an optional, straightforward bush whack up to Rosewood Point), and past the break in the cliff band. Passing the break requires a little Class 3 scrambling. Also be sure to note where you ascended the cliff break, preferably with a GPS, as it can be tricky to find again on your descent.
At this point you will leave the trail and cairns and embark upon about 3/4 of a mile of bush whacking through shin daggers, prickly pear, ocotillo, cat claw, and all other things pokey. Pick your line and head uphill towards the ridgeline and follow it to the backside of The Thumb.
From here the line to the summit ascends a chimney on the northwest side of the summit block. In contrast to the eroding rubble around the northeast side of the block, the rock in this chimney was in my opinion rather competent, though you'll have to make that call for yourself based on conditions and risk tolerance. Ascending the chimney requires some easy, airy 5th class moves followed by a 4th class scramble. Soak up the views--I can't imagine many people visit this summit!
Descend by re-tracing your steps. A rappel down the chimney would not be inappropriate (though it is free climbable); but you'll need to construct your own anchor. I noticed some old webbing up there--DO NOT USE THIS (and make your anchor better than these folks did)!
Check out the Official Route and Triplog.