Rubble Ridge is a short but challenging little trail. It it an alternate route for the South Loop Trail, traversing a rocky ridge, rather than skirting it as the South Loop Trail does. The trail begins with a smooth trail along the base of the ridge, followed by some tight turns, and then a tough little climb punctuated by a short section of some nasty rock garden. The trail then follows the peak of the ridge eastward before wending back west through hardwood trees, up a short climb, then down through twisty cedar, with a sharp left at the end, another tough rocky section, then smooth sailing back to the South Loop. Riding the trail in reverse is a bit easier, but the rock challenges are still there. Note that this is not a natural ridge, but was created by quarrying operations that dumped overburden (the top half-dozen feet of small rocks, dirt, and organic matter) into a long pile. But it's had fifty years to settle into place, and has resulted in a trail that offers some decent climbs and degree of difficulty.