This small dome forms the summit of the Ribcage crags. If you've come this far, and climbed Out of Darkness and Winter Solstice slabs, you might as well finish off your multipitch cactus-climbing adventure by ascending the south face of Upper Dome as well. The excellent online guide lists three short routes up this rock.
Getting There
From the summit of the Solstice slab, drop eastwardly (skier's left, climber's right) down an inobvious, dubious looking gully. The left side the gully is formed by the base of the Upper Dome, so keep hugging the left side of the gully and you'll eventually pass by the base of the climbs. Alternately, you could get there by going up from the base of Right Tower, but there's a boulder move to surmount, and then very nasty brush to climb through (including rasberries, with big, bad thorns).
The routes Winter Solstice and Last Chance can be nicely joined by heading climber's right after the knee-high grass-y-ish plant in the crack but before the very top of Winter Solstice. After heading right, drop into a kind of gulley at the point of the start of Last Chance.
After topping out on Upper Dome via Last Chance, one can lower from the same upper anchor to access Overhang Corner and The Face.
A way to descend from the top of Upper Dome back to the base of Out of Darkness Slab:
once in the notch on the north side of the dome, scramble down west out of the notch, and traverse to skier's right until in relatively open terrain and almost straight uphill from the Left Tower (but now to skier's right);
weave between boulders and grass down towards the tower, passing to skier's left of it as well as the surrounding boulder field;
continue weaving downhill, on approximately the same line; once a little lower than the middle of Out of Darkness Slab, trend skier's left to the base of the slab.
Going this way, you should not have to blast through any bushes or small trees - unless "the way" has been missed.