Limekiln Canyon Park is an unexpected delight in an unlikely place: a raw, natural, open space in the midst of highly manicured gated housing developments in Northridge. Shady, lush and likely to have running water much of the year, it feels surprisingly remote for a location so close to civilization. Though it’s naturally shaded, go early in the day, especially in summer before the heat picks up. Start near the intersection of Rinaldi Street and Tampa Avenue near the park entrance and begin walking downhill on a broad path, past a grassy field and under the shade of oak, pine and even a few redwood trees. (Note the warning about rattlesnakes: another reason to keep your dog on a leash.) At the first Y intersection, just before you reach a creek on your left, leave the wide trail for a narrower one heading up to the right. Walk on, keeping the creek on your left. In the streambed, note the sycamore and willow trees, interrupted by the occasional incongruous fan palm. At the next Y, …