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Hiking the ATOS Loop Trail

by Lee Pearson and Allan Hall

Many of you may be familiar with the great book on horse and hiking trails written by Dana Burden titled “Hiking Out Wickenburg Way”. In his book, Dana documented trails that lead to the ATOS Mine and Balanced Rock, east of Wickenburg. This article ties these two trails together and links them to a third trail that passes from the Hassayampa River up Slim Jim Creek; creating what is essentially a closed-loop trail that is 4.72 miles in length.

We have little doubt that Dana knew about the Slim Jim Creek segment, but he omitted it from his book for reasons that we may never know.

ATOS Trail Map
Figure 1, Trail Loop Map

In any case, combining these three trails into a closed loop, as shown in Figure 1, offers an exceptional hiking opportunity with spectacular scenery and several grand vistas. Hiking this set of trails during March will reward you with a rich variety of Mexican Poppies, Lupine, Owl’s Clover, Deer Vetch, Desert Marigolds, Desert Chicory, Brittle Bush, Arizona Fairy Dusters, Jojoba and a host of less conspicuous flowers. Hiking in April will provide equally spectacular views of ocotillo blooms and many species of cactus.

For seasonal hikers, the best months for this trek are between November and April; when high temperatures range between 60 – 85 degrees. However, see the section titled “Before You Go” at the end of this article.

Getting Started

  1. Beginning at the Wickenburg Rodeo Grounds, drive 10.4 miles to the trail that will lead you into Slim Jim Creek. If you reach the Monte Cristo Mine, you have driven too far.
  2. Turn left and follow the 4WD road until you arrive at a cattle fence. The gate should always remain closed.
  3. After passing through the gate the road will drop into the creek bed.
  4. Turn left and follow the creek bed to the ATOS trailhead.

Warning: Do not enter Slim Jim Creek if there is surface flow at this point, or if there is a threat of significant rain.

ATOS Trail Segment

At the trail head, a 4WD road to the ATOS Mine rises out of Slim Jim Creek to the right. This road point is unmistakable, as you will have reached a location in the creek bed where you can no longer continue forward. Although it is possible to drive a short distance up the road, we recommend that you leave your vehicles in the creek. The first reason will become fairly obvious when you round the first bend above the trailhead. The mine owner constructed a bridge across a gulch that has long since washed away. The only remaining features are a few cyanide barrels that were filled with concrete to support the bridge. It was probably a heart pounding experience to drive a supply wagon over this makeshift construction. As you can see in Figure 2, the bridge pilings could not have met any engineering codes.

Bridge Supports
Figure 2, Bridge supports using cyanide containers

The other reasons for parking in the creek bed are that you will be entering a wilderness designated area where motor vehicles are not allowed; and you will be returning to the trailhead via lower Slim Jim Creek, versus re-hiking the first part of the trail.

Proceed along the old road toward ATOS Mine. There will be several points that offer excellent views of lower Slim Jim Creek, vistas of a distant Hassayampa River and the Weaver Mountains to the north. Notice that you are in an Ocotillo and Saguaro “forest” and the hillsides along the trail are covered with a virtual carpet of flowers during the spring season. See Figure 3.

Lupine and Poppies
Figure 3, Lupine and Poppies on ATOS Trail

After cresting the highest point of the trail (at approximately 3200 feet) the ATOS Mine will come into view; although it will not yet be fully visible. As old mines sites go, the ATOS covers an unusually large area that runs along a northwest to southeast axis. The first features to become visible will be the four cyanide tanks, where pulverized ore was processed to separate the gold. See Figure 4.

Cyanide Tanks
Figure 4, ATOS Cyanide Tanks

From this viewpoint the trail continues downhill toward a gulch that runs generally north to the Hassayampa River. As you proceed down the trail you will encounter a few spots of decomposed granite where the footing could become slippery. Exercising basic caution will get you through this area safely.

When you reach the bottom of the gulch you will see many trees and high desert shrubs. Take a few minutes to explore the area to the right (south) of the trail at this point. Within 100 feet you will find the original well and tank that supplied water for the housing and mine operations. This site appears to provide year-round water due to runoff and springs in the area.

Continuing uphill along the trail (beyond the gulch) will lead you to the edge of the ATOS Mine housing area. There were several buildings on this site and the debris fields of old cans and discarded material is rather extensive.

Housing Area
Figure 5, ATOS Housing Area

Observe and photograph, but please do not disturb or remove objects when walking through these areas!

Beyond the building ruin shown in Figure 5, there is a flat area that contains the remains of a cement slab and other structural ruins. Several of us trekkers (Brown, Hall, Orr and Pearson) have speculated that this area may have contained an enclosed shower facility for mine workers. There is evidence of drainage sinks and piping. Above (and right) of this photo are additional tanks that would have supplied water to this small settlement area.

If you proceed uphill along the trail shown on the left side of Figure 5, you will come to the ATOS Mine shaft at the top of the hill. This shaft is very deep and appears to be slightly inclined in a westerly direction. Figure 6, below, shows that the shaft wall structure was a composite construction of cement and bricks, with an overlaying wood frame. The foundation for the hoist is located behind this photo and almost certainly used a wood structure that extended over the shaft for lifting buckets to the ore hopper.

ATOS Shaft
Figure 6, ATOS Shaft

The ore hopper is one of the smallest I have seen in the Black Rock District. This may be attributed to the fact that mill processing and ore separation was occurring on site. In other words, if you had the ability to process the gold ore without having to ship it to a remote mill, you would not have needed a large hopper. Coincidentally, there are no ore piles near the shaft or other areas of the mine. This would suggest that ore was quickly dispatched to the processing area and did not accumulate in large piles on the mine site.

Aside from the relatively unusual construction of the shaft wall, the front edge contains the owner’s name and the date of construction. See Figure 7.

Figure 7, Inscription on Shaft Wall (photo by Lee Pearson)

As evidenced in the above photo, Alex McLaren commemorated the shaft with this inscription dated March 11, 1940. There is presently little, if any, information that confirms the founding date of the ATOS Mine, but it is believed the shaft was a late addition to the workings. Less than a year later, all non-strategic mines were closed after the advent of World War II.

Several hundred yards north of the shaft (and about 300 feet lower) there is a tunnel that runs in the direction of the shaft. We have surmised that this tunnel was used to remove ore and probably predates the construction of the shaft. There is a strong air flow at the entrance to the tunnel in the direction of the shaft, so we believe they are connected.

While exploring this site, a second tunnel was found near the cyanide processing tanks. No effort has been made to determine if it also connects to the shaft. There is an extensive tailing pile, indicating that it connected with a productive ore vein.

Cyanide Tanks
Figure 8, Cyanide Tanks

For those interested in studying old mine workings and settlements, the ATOS is a worthy destination and could keep you busy for several hours if you choose. Nevertheless, the trail from the cyanide tanks continues on to Balanced Rock.

Balanced Rock Trail Segment

As you proceed along the trail from the tanks you will pass through a fence line and gate that marks the Hassayampa River Canyon Wilderness Area boundary. The gate should remain closed at all times (See Reference Note 1). The trail leads downhill and right (north) into the gulch. The runoff from seasonal rains will produce minor stream flows in the gulch. Otherwise, most of the trail through the gulch could have damp conditions throughout the year. Expect to see abundant wildlife signs in this area, primarily javelina.

The gulch leads into an area that contains a mass of granite boulders on the hillsides. As you proceed through the gulch stay alert for trail signs above and to your left. Hikers have placed rock cairns at several point along the gulch to mark their favorite point to access the trail to Balanced Rock. We too have contributed to this confusion, but recommend that you select the third cairn marker as your point of exit from the gulch (see also GPS Waypoint # 10, below). This quickly takes you to a well established trail that leads in a NNW direction. Within a few minutes you will be able to see Balanced Rock to the north. See Figure 9.

Balanced Rock
Figure 9, Balanced Rock

As in the photo, the primary features in this area are large granite boulders as well as Ocotillo and Saguaro cactus. There are several overlook points that permit you to view the gulch below Balanced Rock. This is rugged, beautiful country and the vistas are impressive. See Reference Note 2.

The trail beyond Balanced Rock turns to the west and slowly descends to the Hassayampa River and the entrance to Slim Jim Creek. There are a few areas of loose granite rubble along the way, so traverse this with appropriate caution. As you descend down the trail you will also encounter a few narrow points that lead you between granite boulders. It is interesting to visualize a prospector trying to coax his mules or burros through these areas.

Most of the present-day trail “maintenance” that occurs on the Balanced Rock segment is provided by wildlife rather than human passage. It is possible (but only conjecture) that this trail is truly ancient. In addition to wildlife usage, it may also have been a Native American trail that provided passage to (or between) hunting areas and the river.

Winter rains generally produce a healthy flow in the upper watershed of the Hassayampa River. If you time your hike between January and April you may see flows that are thirty feet or more in width; unless a heavy winter storm passes through – in which case you are advised to avoid this area. At other times of the year the river typically reverts to sub-surface stream flow at this point.

The final descent on the Balanced Rock trail will bring you to the river’s edge.

River's Edge
Figure 10, River’s Edge

Lower Slim Jim Creek Return Segment

Extensive detail and photos about this segment of the hike in were presented my previous article titled “Hiking in Lower Slim Jim Creek”. Repeated treks through this area confirm that there is significant and persistent wildlife moving through the creek bed. Three items of information need to be amended:

  1. There are three (not two) prospect tunnels near the lower end of Slim Jim Creek. Two of these tunnels are near the creek level on opposite sides; while the third is about forty feet above the creek on the east side. Look for a section of dry stack rock wall above the creek to help you locate this site.
  2. There is now clear evidence that the entire route through the lower creek could be used as a pack trail. Each of the granite dikes have very old (and rough) bypass trails that would have enabled pack animals to pass around these obstacles.
  3. The placer claim now appears to have been abandoned. I have not seen evidence of any site work for about two years.

If you hike the area after a recent storm, there will be many new exposed rocks and pebbles containing chrysicolla, manganese, molybdenum, quartz-magnetite and silver-bearing ores. And as you proceed upstream on the final leg of the hike there will be numerous exposed ore veins and volcanic extrusion dikes.

Trail Conditions

Access to ATOS Trailhead: Reaching the trailhead to the ATOS Mine requires that you travel through the bottom of Slim Jim Creek. Winter rains may produce damp conditions and minor stream flows in the creek bed for several weeks after a major storm, but these conditions generally do not hamper or prevent access. A high clearance 4WD is essential, regardless of the time of year. Heavy rains, particularly during the monsoon season, can cause Slim Jim Creek to “reinvent” itself due to high runoff. Boulders are frequently moved and channels changed in course by high water flow. In other words, you should expect to encounter trail obstacles.

Parking at the ATOS Trailhead: With a bit of ingenuity, four or five 4WD vehicles can be parked at the base of the trailhead. It is recommended you “think small” when taking a vehicle into the area. Jeeps and mid-sized 4WD trucks will have no difficulty in traveling down Slim Jim Creek and finding suitable parking spots.

Hiking Trail Conditions: The ATOS trail segment follows the old road to the mine area. Although it is not maintained, hiking conditions are generally excellent. There are a few down-slope areas where you will encounter loose, decomposed granite.

Suitability for Horses: The ATOS Trail segment is quite suitable for horses, having observed horse tracks and biscuits along this trail in previous outings. Getting a horse trailer to the trailhead is problematic, however, and it may be necessary to begin your ride from the turnoff point near the Monte Cristo Mine at Constellation Road. Our judgment is that Balanced Rock and Slim Jim Creek trail segments are not safe for horses. If anyone has better information on this topic, please let us know!

The Balanced Rock trail segment leads from the ATOS Mine into a gulch that drains the watershed in this area. The gulch can be damp or have minor stream flow at any time of the year. The trail then leads up a hillside as it proceeds north to Balanced Rock and on to the Hassayampa River. It is a narrow footpath, but is well established. Some modest clearing of brush and tree limbs (Feb-Mar 2008) has been performed to provide easier passage. Seasonal growth of mesquite and Palo Verde trees will inevitably constrict passage in some spots. A machete is a handy tool to bring with you on this hike.

The return leg of the hike through lower Slim Jim Creek is also subject to runoff and may have damp conditions or minor stream flows. There are two granite dikes (twelve to eighteen feet in height) that you will have to climb. The elevation gain from the Hassayampa River returning to the ATOS Trailhead (starting point) is 452 feet. Except for the two dikes, this trail segment is a steady gain in elevation with sandy streambed conditions.


This loop trail passes through State Trust and BLM land that includes the southwestern portion of the Hassayampa River Canyon Wilderness Area. It is remote, rugged and beautiful country. Because it is isolated from human activity, you will have an opportunity to see javelina, deer, mountain lions, Gila Monsters, great horned owls, red-tailed hawks and a host of migratory birds.

This area is particularly well suited for mountain lions, javelina and deer. Large herds of javelina have been tracked on all three segments of the trail as well as mountain lions for up to a half-mile in the lower segment of Slim Jim Creek. Humans tend to be pretty noisy, especially when in groups. Although you may not see any of these critters, they are there. You are hiking through their habitat and their tracks will provide ample evidence.

A word of caution: The prospect tunnels at the lower end of Slim Jim Creek may serve as seasonal habitat for javelina with young offspring. Great Horned Owls also use these tunnels during the day to escape the heat and light. Approach the tunnel entrances with due care.

Useful GPS Waypoints

If you use a GPS unit when you hike, there are a number of Waypoints that you may find useful for this trek. All coordinates are listed using WGS84 datum. Accuracy is within fifteen feet.

1. Wickenburg Rodeo Grounds (Mile 0): N 33 o 58′ 50″ by W 112 o 42′ 38″
2. Turnoff to Slim Jim Creek (Mile 10.4): N 34o 03′ 54.8″ by W 112 o 35′ 06.7″
3. Arrival at Slim Jim Creek: N 34 o 04′ 26.0″ by W 112 o 35′ 24.8″
4. ATOS Trailhead: N 34 o 04′ 34.0″ by W 112 o 35′ 50.8″
5. ATOS Housing Area: N 34 o 05′ 90.2″ by W 112 o 36′ 08.1″
6. ATOS Mine Shaft: N 34 o 05′ 13.1″ by W 112 o 36′ 03.3″
7. Tunnel #1: N 34o 05′ 11.9″ by W 112 o 36′ 14.1″
8. Cyanide Tanks: N 34 o 05′ 05.8″ by W 112 o 36′ 19.9″
9. ATOS Gulch: N 34 o 05′ 01.7″ by W 112 o 36′ 26.9″
10. Trailhead to Balanced Rock: N 34 o 05′ 01.5″ by W 112 o 36′ 36.0″
11. Balanced Rock: N 34 o 05′ 01.9″ by W 112 o 36′ 44.1″
12. Terminus of Balanced Rock Trail: N 34 o 04′ 57.9″ by W 112 o 36′ 57.0″
13. Entrance to lower Slim Jim Creek at River: N 34 o 04′ 57.0″ by W 112 o 36′ 57.9″
14. Prospect Tunnels: N 34 o 04′ 48.7″ by W 112 o 36′ 50.7″
15. Terminus of Hike at ATOS Trailhead: Same as #4.

Download the GPX file of Tracks for this hike.

Before You Go

  1. The term “safe mine” is an oxymoron. There is no such thing as a safe mine – particularly one that has been abandoned for many decades. Although you may be tempted to explore this or other mine entrances, understand that they are inherently dangerous. Tunnel entrances frequently serve as seasonal habitats for rattlesnakes and javelina. Tunnels may slough overhead rocks and there may be vertical shafts (winzes) that connect one tunnel to a lower level. If you want to be safe, stay out of mines!
  2. This is not a technically difficult hike and it requires only moderate exertion during the cool season. Nevertheless, you should be in good physical condition. The final leg of the hike (through lower slim Jim Creek) will require a higher level of exertion during the May-October time frame.
  3. Plan to carry sufficient water and energy snacks for this hike. Make sure that you have additional water in your vehicle when you return.
  4. Let someone know where you will be and when you plan to return. From the departure point at the Rodeo Grounds, you can expect this outing to take seven to eight hours – longer if you spend extra time exploring the ATOS Mine area.
  5. Unless you intend to camp overnight, you should plan to exit from Slim Jim Creek while there is still daylight.
  6. Be on the watch for snakes during the warmer seasons.


  1. We have observed OHV tire tracks inside the wilderness area on previous hikes. If you see any vehicles (ATVs, dirt bikes, etc.) beyond the gate, please report your sighting to the BLM. The main telephone number in Phoenix is: (602) 417-9200, or contact
    Teri A. Raml, District Manager
    21605 N. 7th Avenue
    Phoenix, AZ 85027-2929
    Phone: (623) 580-5500
    Fax: (623) 580-5580
  2. The Balanced Rock Trail actually connects to the White Mine, about 1.5 miles to the west. It is likely this was also a pack trail between the 1870’s and the early 1900’s.
  3. Historical Footnote: There is a bit of friendly debate about the origin of the ATOS Mine, particularly with respect to the mine located due east, shown inside the red oval on the map image in Figure 1 (upper right in image).

The authors believe that the mine to the east is the George Washington Mine, alternatively known as “Atos Gold.” The George Washington mine owner’s report, filed by Steve Loncar, dated April 2nd 1940, describes the mine as comprising four tunnels and four shafts with no employees, no mill and no equipment. Mr. Loncar describes the route to his mine as one mile beyond the Constellation Post Office, then 1.5 miles beyond Constellation Road. In our opinion, the George Washington (Atos Gold) Mine is not the same as the ATOS Mine since the route to the ATOS is entirely different. There are no connecting roads or trails between these two mines.

Because the “ATOS Mine” shaft wall records the name of Alex McLaren with a date of March 11, 1940, we believe it is unlikely this mine is related to George Washington Mine to the east. The ATOS Mine had a settlement and extensive milling operations. It also has only one shaft and two tunnels.

Last 5 posts by Allan Hall

5 comments to Hiking the ATOS Loop Trail

  • Excellent map. I will try this one out.

  • Allan Hall

    Hello Franchise:
    Lee and I have hiked the return leg through lower Slim Jim Creek when it was 102 degrees. Although this leg only gains 452 feet in elevation, it can be a tedious hike when the temperatures are high. If you’ve hiked uphill through a sandy creekbed, you will know what we mean! Damp conditions are actually beneficial, because the sandy creekbed provides a sturdier, more compacted surface.

    May temperatures are now trending upward, so please exercise due caution.
    For the record, I do not hike in lower Slim Jim Creek between July-September.
    Best regards.

  • katrina z

    Anyone know how to get to “Deaf Joe Cabin” that is somewhere in this area? If one did not have a 4wd vehicle, but strong and sturdy legs, could one drive to the first 4wd turnoff- then how far is it to the ALROS TH?

    • Allan Hall

      Katrina Z,
      I’ve hiked this area pretty thoroughly and I have never heard of “Deaf Joe Cabin” from any long-time locals. There are a few abandoned cabins/miner’s shacks in the general area, and also a number of foundations where cabins may have been at one time.

      Regarding your question about “… the ALROS TH,” I can only say that texting while driving is dangerous.

  • katrina z

    Ha! ALTOS TH (trail head)
    I don’t even own a cell phone, Allen. I just suck at typing! Thanks for the info… and chuckle