Aliso means “Sycamore” in Spanish and this delightful little canyon is full of them. Within the three mile loop you’ll find a variety of plant life, from riparian vegetation in the canyon to oak meadows and grass-covered hills on the upper part of the trail. There, you will find grass-covered views of the surrounding valley and in the spring you’ll also discover an abundance of wildflowers both in the canyon and on the upper trail. This is a nice trail for kids.
Though the trail is in relatively good condition after the White Fire in late May 2013, the section of the trail leading out of the upper canyon to the higher areas has some extremely exposed parts. This is due in part because the hillside is steep but also the fact that there is almost no vegetation, meaning if you start sliding or rolling down the hill you are most likely going all the way to the bottom.
At the upper end of Sage Hill you’ll find the start of Aliso Canyon Nature Trail. Either at the trailhead or the nearby Ranger Station you can pick up a pamphlet describing various plants and geological features you’ll find along the way.
Almost immediately, you are plunged into the canyon, which twists and winds for a mile and then climbs somewhat steeply up onto a saddle formed by a fault line that cuts across the front side of the mountains. It is part of a larger complex of faults known as the Little Pine Fault. Exposed along it are bluish-green serpentines and in some places along the creek a formation known as “pillow lava”—molten material that oozed up out of the ocean floor. The black igneous rock looks like something like egg white that has cooked in boiling water.
A short ways into the canyon you’ll notice a trail intersecting on the right. This is the end of the loop that you will be returning on. You can also turn right and take the trail in this direction, but you’ll find that most of the uphill is right above you. Continuing up the canyon allows for a more gradual elevation gain.
At the saddle in the fault line you face a choice. One trail leads straight ahead and downhill. This leads to Upper Oso. The right fork goes up over a steep hill. To continue the loop hike, turn right and make your way over the knoll. Just beyond this is a second knoll—the high point, from which you can inhale the delicate smells of the sage and absorb the wonderful views. Beyond this the trail gradually turns to the right and follows a ridgeline which eventually leads back down into the canyon. As the trail descends you’ll find yourself back in oak forests and fern-covered hillsides as you switch back and forth into Aliso Canyon.
If you’re feeling a bit rambunctious, before heading back drop down into Upper Oso. From there you can explore a bit of Oso Canyon before turning back. A short trail also leads down canyon from Upper Oso to the Lower Oso picnic area. Information for these hikes can be found in the next few pages.