This is the Corkscrew Redwood in Prairie Creek Redwoods State Park.
The redwood is easy to find. As long as it stands, there should be a small sign a short distance north of Cal-Barrel Rd., along Drury Parkway, on the west side of the Rd. A short path leads down ... a brief one or two minute walk. There should also be a short spur path from Prairie Creek trail to reach this redwood.
At present ( October 2015), the National Park Service states on its trails south page, that the redwood is an excellent example of a "Fairy Ring. I do not agree. The corkscrew redwood is an excellent example of something very unusual. But there are far better examples of fairy ring redwoods like the Titanic Cathedral. Also, the corkscrew characteristics connote origin from several redwoods in close proximity.
I've been trying to decipher the corkscrew redwood for years, and have one theory that may fit all its characteristics. I think the trunks grew around a medium size redwood, or large Douglas fir, western hemlock or Sitka spruce. And whatever was in the middle .. died, rotted or burned. The lack of related wood on the ground has me ruling-out a redwood stem. Also, if a redwood, or other, burned-away, we would probably not see intact bark on the inside convex of remaining trunks. Fire would torch that bark and cambium otherwise. That has me leaning toward decay, and suspecting something like spruce or hemlock wedged in the center, and later died and decayed.
A redwood center can't be ruled-out altogether. And there's a chance it's a fairy ring. But with missing pieces to the puzzle, and given the forms, I believe this redwood is telling a much different story.
If a spruce were in it's midst, with several redwoods encircling, the redwoods would expand and press against the spuce's round trunk, leaving the concave shapes. Spruce don't tend to live as long, and the wood decays quickly. Over decades, spruce would disintegrate, leaving a void. The void of the missing trunk and spruce canopy would remove some support and protection from wind. With missing resistance in the midst, various storms could twist remaining redwood stems into new contorted forms.