Squarenail is named for remains of a logging flume that crossed the dome in the 1890's. The flume floated lumber from Shaver Lake to Clovis. A few pieces of lumber from the flume and many square nails that held the flume together can still be found around the base and in the descent gullies. Enjoy the nails when you find them, but please leave them be. They will just get lost if you take them home. Along the top of the dome can be found two lines of parallel cuts into the rock where the legs of the flume were set into the rock. The cuts are pretty far apart so you have to hunt for them.
The dome was developed for climbing in the late 1960's, early 1970's by Rich Calderwood as a location to teach his Fresno State climbing class. A number of single bolts were placed along the edge of playground ledge for lowering and top roping students. Students also practiced bolting 3 separate lines on the Aid Boulder. A variety of bolts were used on the Aid Boulder and many pulled out over the years.
Though people climbed there through the 1970's it does not appear that any new routes were added until around 1980 when Paul Martzen, Dwight Kroll, Barry Chambers and a few others started adding a few trad and top rope routes. Starting in 1991, Mark Spencer and various partners added a large number of bolted sport routes, which now tend to be popular because they are well protected.
Squarenail is a sister crag to Tollhouse Rock, being at the same elevation and just across a small canyon. It is much smaller than Tollhouse and more broken up, making it difficult to traverse the whole base. Squarenail tends to be a bit steeper than most of Tollhouse. Like Tollhouse access is to the top of the crag and climbers descend to the base to access the climbing routes. Each section of rock has its own best descent route.
Climbers tend to use Squarenail once the weather has cooled off in the fall, through the winter and into spring. The cliff faces south and slightly east. In the summer it is very hot at Squarenail, but the cliff does go into shade around 4 PM, so summer evening climbing is feasible.