If you've spent any time in the Illinois Valley area, you've noticed that the landscape looks much different than the coastal mountains to the north or the Cascades to the east.

If you've spent any time in the Illinois Valley area, you've noticed that the landscape looks much different than the coastal mountains to the north or the Cascades to the east.

The Siskiyou Mountains were misshapen and discolored by a rare geologic process that exposed formations of earth mantle usually found only under the ocean. Sometimes the geology abruptly changes. One minute you're in an old-growth forest and the terrain breaks through into a wide open area where the only things growing are grass, flowers and dwarf trees.

You can learn about the area's geology by hiking the short yet challenging, two-mile-long Serpentine Contact Trail near the Illinois River and right along the TJ Howell Botanical Drive. To get there, head west on Eight Dollar Mountain Road from Highway 199 just south of Selma.

You'll cross a bridge, pass Josephine Camp Campground and continue on Forest Service Road 4201, which is mostly in good shape but in some places is "washboarded" out.

About eight miles from Highway 199 there is an obvious parking area, picnic table and interpretive sign. This is at around 3,000 feet elevation, so it could be snowed in at times.

There is also a trailhead sign with an arrow pointing down a skid row once used to bring logs up this slope. Follow the signs and see how big some of the old stumps are.

In less than a quarter mile, the skid row enters a shady area forested by several different species, including Ponderosa and sugar pine, Douglas fir, canyon live oak, tanoak and madrone. In the spring you can spot the many California ground cones, a native parasitic plant that grows straight from the ground, tapping nutrients from manzanita and madrone.

This is the quintessential Southern Oregon forest: diverse, routinely scarred by wildfire and full of history.

You'll find some of that history about a half-mile into the hike, where the road descends to a saddle at an old mine site. You might want to look around, but don't follow the spur road. Do follow the signs and keep your eyes open for a hiking trail that veers right off the old road track.

If you descend and end up back on Eight Dollar Mountain Road, you missed the faint, barely signed trail. Turn around and find it in the wooded area, watching closely for trail signs.

When you do find it, which can take a couple of strikes, the trail is in really good shape. Its tread is wide and was well surveyed. It winds around some large conifers and makes a couple of switchbacks along the ridge.

Wildlife may prefer this strategic divide for travel, and you are likely to see signs of deer, bear and even cougar while up along the ridge top. You could catch some sights and sounds, too, especially if you decide to spend the night.

At just less than a mile, the trail leaves the forest and gives way to a rocky open area with not much growing other than some grass, manzanita and dwarf trees. The contrast can be abrupt, but you haven't stepped into the twilight zone. You have stepped into a serpentine intrusion whose heavy iron content oxidized over time and morphed into red rock called peridotite, which dominates much of the Josephine ultramafic sheet.

Forty or so million years ago here, you would have seen a volcanic vent oozing molten rock into the sea. In most cases that molten rock would stay underwater, hidden by salty ocean waters. But in the Siskiyous, this specimen of earth mantle was scraped, folded and twisted onto the North American continent, leaving a geologic rarity exposed for us terrestrial travelers to enjoy.

After entering this rare landscape, the trail heads up around some carefully built rock walls and ends at a knob with a couple of picnic benches, about a mile from the trailhead. Sit and soak in the views.

If you feel like poking around, beyond the benches is an unnamed peak that could be the highlight of this hike for those who seek it, and while there is no trail to it, its summit is a fun detour that adds challenge.

Walking back, which is a quick but tough climb, you'll feel the geology under your feet, biting at the soles of your boots. Check out how tight the grain is of the downed, slow-growing trees along the rocky section, and compare them to the faster-growing, larger growth rings in the stumps atop the hill.

This challenging hike is a great half-day reminder that this is not the Cascade or Sierra mountain range. It's not even the coast range. This is the Siskiyou.

Freelance writer Gabe Howe is executive director and field coordinator for the Siskiyou Mountain Club. Contact him at howegabe@gmail.com.