Osborne Hill Trails

Not exactly wild but not tame either, the Osborne Hill Trail area makes up the southern arm of Empire Mine State Historic Park. The excellent trail system here has many loops, making for boundless riding or hiking options through deep woods and some open areas. There are remnants of several significant mines. Pits and piles of mine tailings are commonplace. Whether you are on foot, horseback or bicycle, this is one of the most intriguing sections of Empire Mine State Historic Park to explore and enjoy.

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Place: Grass Valley, CA

Season: Year around

Land: Empire Mine State Historic Park

Trail signs: Some, with more planned. Best to carry a good trail map.

Length: Depends on route taken. Total 4 miles of trail in the Osborne Hill Trail Area.

Altitude change: Depends on the trail taken. Maximum elevation difference is about 290′

Difficulty: Easy to moderate depending on route taken.

Trail surface: Recently refurbished, all trails in this area are in excellent condition; most with rock base and compacted surface. Trail widths range from single track to truck-width mining roads. Trail segments crossing wet places are armored with stone.

Environment: Former area of heavy mining activity over many decades now reverting to native mixed conifer and hardwood forest. Some hazardous places remain closed.

Facilities: One picnic table near the top of Inner Loop. No other facilities.

Rules: Trails open from dawn to dusk; stay on marked trails; no motor vehicles; no camping; dogs must be on leash; all natural and historic features are protected. Stay out of closed areas. Caution:  poison oak, ticks, rattlesnakes

Trailheads:  Of the three trail areas in Empire Mine State Historic Park, the Osborne Hill Trail Area is the only one that does not have a trailhead with parking immediately adjoining the trail system. Official access to the Osborne Hill trails is from the following two trailheads, located along East Empire Street:

Penn Gate Trailhead: From Highway 49 in Grass Valley go 1/2 mile east on Empire Street and enter the trailhead parking area on your right. There is a large supplemental parking area for horse trailers behind the car parking lot. To reach the Osborne Hill trails, follow the popular Hardrock Trail south from the Penn Gate (N39.20940 W121.05717) about a mile to either the Osborne Loop Crosscut Trail (N39.20018 W121.05336) or the Osborne Loop Trail (N39.20173 W121.04544), both of which will be on your right.

Visitor Center Trailhead: From Highway 49 in Grass Valley go east on Empire Street 1.25 miles to the main visitor parking lot at Empire Mine State Historic Park. At the far southeast end of the main parking lot (to your left as you face the mine yard) you will find a metal gate and wayside exhibit that form the eastern trailhead for the Hardrock Trail (N39.20663 W121.04493). To reach the Osborne Hill trails, follow the Hardrock Trail south about 0.4 mile. Just after you cross Little Wolf Creek take the Osborne Loop Trail (N39.20173 W121.04544) uphill and south from the Hardrock Trail.

A bit of history: The Empire Mine State Park area as you see it today contained a complex of mines that were developed to get at gold-bearing rock veins below the surface. There were at least five mines in the Osborne Hill area, with varying levels of mining activity from the 1850’s into the 1930’s. Most easily visible here are impressive remains of the Prescott Hill Mine which, combined with several neighboring mine properties in 1903, had a shaft down to 1,750′ and was active into the early 1930’s.

Trail tips: The Osborne Hill Trail Area has seven named trails packed into less than 300 heavily wooded acres. There are enough “loop” trails and “crosscut” trails in the system to befuddle even a seasoned trail user. Add to this a present (early in 2014) lack of detailed trail signage and you have a significant potential for new visitors to become disoriented. For this reason, it is a good idea to carry a current and accurate map if you are new to these trails. The map above should serve you well. Or you can go to the park Visitor Center and pick up the free color brochure captioned “Empire Mine State Historic Park” with a maroon color band on the front. The excellent map inside contains the latest official routes and names of all important trails in the park. On that map, the Osborne Hill Trail Area is all of the state park land south of Little Wolf Creek.

The top trail tip for the Osborne Hill Trail Area is to use a good map and invent your own favorite routes. This is truly an area that invites do-it-yourself exploring.

For those who would like more specific suggestions, the following are two possible routes to try as an introduction to the Osborne Hill Trail Area:

Penn Gate Trailhead – Total 4.25 miles: Quick description: From the Penn Gate Trailhead an easy run out the Hardrock Trail followed by a long gentle climb up the west side of the Osborne Hill trail system to the lovely Conlon Mine Trail high on Osborne Hill, then down the middle of the trail system to the Prescott Hill Mine, back over to the Hardrock Trail near the Little Wolf Creek crossing, then back to Penn Gate on the Hardrock Trail. Maximum elevation difference is about 380′.

Detailed description: The first leg of this route is a nearly level stretch of the Hardrock Trail going south from Penn Gate. About 0.6 mile from the gate, where Little Wolf Creek goes down a spillway, there is a fork in the trail. Horses must go right; all others can keep left. Either way, you will return to the main trail shortly and then start uphill. After about 130 yards of uphill travel you will find the Osborne Loop Crosscut Trail going off to your right. This is your entry into the Osborne Hill trail system.

Follow the Osborne Loop Crosscut Trail as it climbs gently through open hardwood, pine and manzanita forest, then enters heavier cover of pine and incense cedar. After 1/2 mile on this trail you will reach the western part of the Osborne Hill Loop Trail which circles the entire Osborne Hill Trail Area. Go right and uphill now on the Osborne Hill Loop Trail for about 0.6 mile. The trail is wide here and the forest becomes more open. You may catch views of distant ridgelines to the west. When you are nearing the top of the hill you will see a wide graveled trail dropping down to your right then leveling out. This is the west end of the Conlon Mine Trail which offers a particularly sunny and pleasant detour out to the vicinity of the old Conlon Mine then back to the top of the trail system on Osborne Hill.

Take the Conlon Mine Trail and follow it for a little over 0.4 mile. This is an elongated loop, along which you will see several massive piles of mine tailings now partially overgrown with pines, oaks and large manzanita. (At a sharp curve on the southeast side of the loop there is an unofficial trail off to your right that you can follow a few dozen yards to see old cement foundations left from the Conlon Mine operations.) The main Conlon Mine Trail continues north from this curve and soon passes through a gate in a wire mesh fence, ending in a level clearing with a locked metal gate visible over to your right. This is an access gate for park personnel located along a private road called Osborne Hill Road. (You may also note that there is a trail leading off downhill from the left side of the locked metal gate as you look toward the road. This is the easterly continuation of the Osborne Hill Loop Trail. If you were to take it, you would follow the eastern boundary of the Osborne Hill Trail Area down to the Prescott Hill Mine, then go back out to the Hardrock Trail near Little Wolf Creek.)

To continue with the presently suggested route, turn your back on the gate and go left as you emerge from the Conlon Mine Trail. In less than 50 yards you will come to a trail junction. The wide trail coming up from your left is the top of the Osborne Hill Loop Trail that you followed when you came up the west side to the Conlon Mine Trail. Straight ahead is what park officials call the “Inner Loop.” It offers a quicker return to the base of the Osborne Hill Trail Area than the outside loop around the periphery.

Heading north on the “Inner Loop” you will see on your left, after about 50 yards, the only picnic table in the Osborne Hill area of the park. It’s a good place to stop and sit, if you wish. Continuing north from there, the “Inner Loop” trail is quite wide for a while, then abruptly becomes a single track as it drops down into heavy forest. You will cross a small wooden footbridge located about 0.3 mile from the start, then, in less than 200 yards beyond the footbridge, you will find yourself crossing a power line corridor that runs east-west through the park. (Here, below the power lines, you will see a single track trail coming in from your right. This is the short Betsy Mine Trail connecting the “Inner Loop” to the main Osborne Hill Loop Trail along the eastern edge of the park.)

About 90 yards past the intersection with the Betsy Mine Trail, the “Inner Loop” comes to another intersection and the trail width suddenly increases. Don’t go right. It leads quickly to a dead end. Instead go left on this wider trail for about 100 yards where you will find yet another intersection. This is the intersection of the “Inner Loop” with the

Prescott Hill Crosscut Trail, which is a wide road at this point. (If you were to go left on the Prescott Hill Crosscut Trail for 1/3 mile you would come out on the western side of the trail area.)

At the intersection just mentioned, go right on the Prescott Hill Crosscut Trail. It drops fairly sharply and in less than 50 yards makes a “T” intersection with an old mining road. This mining road is the Osborne Hill Loop Trail in this part of the park. Go left on the Osborne Hill Loop Trail. A short distance after the “T” you will see some deteriorating cement foundations on your left being taken over by the forest and, on your right, rock tailings towering above you. A little farther on, you’ll encounter the very large and more intact cement foundations of the Prescott Hill Mine, with a park sign identifying the mine. (Just past the latter, you will see a trail going off to the right. This is the Prescott Mine Trail, a 1/3 mile easy path that runs east behind the Prescott Hill Mine tailings and comes out onto the Osborne Hill Loop Trail behind you, a bit east of where you went left from the Prescott Hill Crosscut Trail.)

From the Prescott Hill Mine ruins continue west on the Osborne Hill Loop Trail about 0.2 mile, keeping right at the only other intersection you will see along the way. This will bring you out of the Osborne Hill Trail Area and onto the Hardrock Trail at a point about 0.4 miles beyond where you first left it to take the Osborne Hill Crosscut Trail. Turn left on the Hardrock Trail and follow it 1.2 miles back to the Penn Gate trailhead.

Visitor Center Trailhead – Total 2.2 miles: Quick description: A short foray down the Hardrock Trail from the Visitor Center trailhead to reach the Osborne Hill Loop Trail, then past historic remnants of the Prescott Hill Mine to the east side of the Osborne Hill trail system, going over to the west side on the short Betsy Mine Trail plus the easy Prescott Hill Crosscut Trail, then returning to the Visitor Center trailhead by going down Osborne Hill Loop Trail and back out the Hardrock Trail. Maximum elevation difference about 120′.

Detailed description: From the Visitor Center trailhead take the Hardrock Trail south about 0.4 mile. You will pass the remnants of the Orleans Mine on your left, then the old Orleans Stamp Mill foundations on your right. These landmarks have signs. Less than 80 yards past the Stamp Mill, take the first trail you see on your right. This is a nice shortcut that in about 150 yards will take you across a wooden bridge over Little Wolf Creek and return you to the Hardrock Trail. You will now be at the intersection of the Hardrock Trail and the Osborne Hill Loop Trail. This is your entry to the Osborne Hill Trail Area.

Go uphill on the Osborne Hill Loop Trail, keeping to your left. In a little over 100 yards you will see a wide trail going off to your right. This is where you will come out on your return to the Visitor Center. Pass it by for now and keep going straight. In another couple of hundred yards you will come to the impressive remains of the Prescott Hill Mine. There will be large cement foundation walls on your left with a sign announcing the mine. You will also see huge piles of mine tailings in this area.

Continuing past the Prescott Hill Mine sign you will soon see a smaller group of old cement foundations, this time on your right. Another 50 yards or so past these foundations you will come to an intersection with a wide trail heading sharply uphill to your right. This is the eastern end of the Prescott Hill Crosscut Trail. You will be on another part of that trail in a few minutes. For now, pass it by and continue straight and a bit uphill for another 100 yards where you will arrive at a “T” intersection.

(The trail on your left is the Prescott Mine Trail, a 1/3 mile easy path that goes west behind the Prescott Hill Mine and comes out onto the main trail near where you saw the Prescott Mine sign. The gap in the fence ahead provides quick access for park personnel but is not a public entry point. The trail on your right is a continuation of the Osborne Hill Loop Trail.)

Go right on the Osborne Hill Loop Trail. It narrows to a single track going south and gently uphill. You may see vehicles on Osborne Hill Road just outside the park boundary on your left. It is a restricted private road from which there is no official access to the park.

About 200 yards up this part of the Osborne Hill Loop Trail you will go through a gap in a wire mesh fence and find yourself in a power line corridor that has jumbled terrain beneath the power lines. You are at an important junction. Over to your left there will be a locked gate. Ahead and a bit to the left, the Osborne Hill Loop Trail continues uphill near the road. In front of you there will be a large wooden power pole set in the ground with a single-track trail of crushed rock going to the right of it and curving into the woods. This is the east end of the Betsy Mine Trail.

Take the Betsy Mine Trail on the right. The entire trail is only about 230 yards long but interesting since it runs in part along a raised and curving earthen berm where ore cars or mining vehicles once ran. If you look closely, you will also see remnants of mining ditches that brought water for mining activities. Soon you will come back into the power line corridor and, here, the Betsy Mine Trail will angle into another trail that crosses the corridor from your left to right. This is the “Inner Loop” trail coming down from the highest part of the Osborne Hill Trail Area.

Merge with the “Inner Loop” trail and keep going downhill on it for about 90 yards. You will come to an intersection where the trail width suddenly increases. Don’t go right. It leads quickly to a dead end. Instead go left on this wider trail for about 100 yards to where you will find another intersection. It is the intersection of the “Inner Loop” with the Prescott Hill Crosscut Trail.

Now go left on the Prescott Hill Crosscut Trail. For a little less than 150 yards you will be on a very wide and level roadbed, and you will be looking down to your right through the forest onto the massive tailings of the Prescott Hill Mine which you recently passed on the lower trail. The Prescott Hill Crosscut Trail then narrows, curves left, climbs briefly and makes an easy and pleasant run (less than 1/3 mile) through forest over to the west side of the trail area. You will find yourself once again in the power line corridor for a short distance and then you will reach a “T” intersection. The wide trail running from your left to your right here is the western branch of the Osborne Hill Loop Trail.

Turn right and go downhill on the Osborne Hill Loop Trail. This will take you back to the Hardrock Trail in a little over 1/3 mile. Be careful not to take a trail you will see on your left when you are about 280 yards down the Osborne Hill Loop Trail from the intersection by the power lines. (This is the Osborne Loop Crosscut Trail which goes off to the west for 1/2 mile to join the Hardrock Trail in a different part of the park.)

About 150 yards down the Osborne Hill Loop Trail past the intersection just mentioned, the trail widens suddenly and comes to a final intersection where the western and eastern branches of the Osborne Hill Loop Trail meet. Go left at this intersection for a little over 100 yards. This will bring you out of the Osborne Hill Trail Area and onto the Hardrock Trail. You can then either go back across the footbridge over Little Wolf Creek or go right on the Hardrock Trail (it crosses the creek over corrugated metal culverts) and return 0.4 mile to the Visitor Center trailhead on the Hardrock Trail.

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