The Fourth Flatiron is probably the least climbed Flatiron (and the last to be added to this site as well). It is a giant piece of rock, easily bigger than the 3rd, but it is broken up into three sections separated by south facing gullies, breaking up any clean climbing lines from base to summit. The first section begins right off the Royal Arch Trail (although this spot is not obvious, see below), and the second section sweeps up into several summits, the most northern of which is Green Mountain Pinnacle (a separate rock on this site). The third section sweeps up and merges with the SE ridge of Green Mountain.The summit of the third section is the highest of the five Flatirons, and it is also the easiest to downclimb off of.
To find the base of the Fourth Flatiron, head up the Royal Arch trail to Sentinel Pass. Here the trail goes down steeply for a hundred feet or so, then levels off. Right after passing the Fourth Flatironette, the trail starts up again steeply on some switchbacks. There is a weird diagonal cave under the south face of the Fourth Flatironette that can be a useful spot in a downpour. The next rock you come up to is the Fourth Flatiron, it is only a few feet right of the trail itself. After you pass the base of the Fourth, you know you've gone too far when you cross a drainage (Tangen Spring); during wet periods there is actually a stream going down the trail here and it may be icy in the winter.
Browse More Classics in Fourth Flatiron
Mountain Project's determination of some of the classic, most popular, highest rated routes for Fourth Flatiron:
No Balls At All V1 Boulder, 1 pitch, 80 feet
East Face, North Side 5.2 Trad, 3 pitches, 150 feet
East Face, South Side 5.4 Trad
East Face/4th Flatiron 5.4 R Trad, 10 pitches, 1000 feet
Excellent Crack 5.8 Trad, 1 pitch, 80 feet
Featured Route For Fourth Flatiron
Lower South-East Gully 5.4 CO : Flatirons : ... : Fourth Flatiron
We actually accidentally climbed this to short-cut from "Zacheus, 10d," and "DC Boy, 11d," on the Lower East Face of the Fourth to "Death and Transfiguration" on Green Mountain Pinnacle. The best Flatiron book describing the area is the one by Jason Hass, 2009....[more] Browse More Classics in CO