Pinto Wye Arrastra

An arrastra is a simple and primitive gold milling device. Heavy stones are dragged over gold ore to crush it. Mercury and water are added to the floor of the arrastra to create an amalgam and capture the gold.

There is somewhat of a mystery about who built this arrastra and used it. There is a small incline shaft up on the hillside above the arrastra and there are a couple of prospects in the area. The arrastra could have been built to mill ore from these prospects. Perhaps the ore played out too quickly and the miners moved on before using the arrastra heavily.

It is also possible that this was a custom mill for other mines in the area, maybe it was centrally located to serve some of the other mines?

The location in the backcountry of Joshua Tree National Park is also a bit of a mystery too because there is no good source of water nearby. It would have needed to be brought in for the arrastra to work.

The design itself of the arrastra is also rare because of that wagon wheel sitting on top. It is a “wagon wheel” arrastra, meaning that a wagon wheel is attached to the central axis to drive the drag stones. This type of arrangement is quite unusual and very few, if any, are left in the wild. This is the only known remaining example of this type in the backcountry of a National Park.

Typically, arrastras were driven by walking a mule or horse around the perimeter. The wagon wheel design was to accommodate a belt for an engine, in this case a four horsepower International gasoline engine (long since removed), to power the arrastra. Having two wheels on the arrastra allowed for switching the rotation speed of the crushing stones. The larger wheel was probably added later to reduce the revolutions per minute and slow the crushing down to a desired speed.

The gasoline engine suggests a date after 1900s for the arrastra but probably before the end of the Great Depression in the 1930s. The Monument was created in 1936 and no new mining claims would have been allowed after that date; work on existing claims could continue. So, it is likely the arrastra was built before then. There is a small sign at the site explaining the workings of the arrastra.

Getting There

There is no trailhead or parking lot close to the arrastra site so you will have to find a good spot to park on the side of the road. Be sure to pull all the way off the pavement so you aren’t in the way of traffic. I pulled off at a spot just 0.3 miles (0.5 km) south of the Pinto Wye on Park Blvd. It is just beyond where a sandy wash crosses the road. (Do not drive off road or in the wash.) Where is the Pinto Wye you ask? Well, it is one of the park’s major intersections. It is a “Y” shaped three-way road junction. It is about 4.5 miles (7.2 km) south from the Twentynine Palms (North) Entrance station and 3.5 miles (5.6 km) north of Jumbo Rocks campground.

Hike Directions

Hike Distance1.5 miles (2.4km) Out & Back
Trail TypeCross-Country
Hike DifficultyEasy
Elevation Gain, Loss240 ft (73m) gain round trip.
Hike Time1 hour

From the side of the road, head north and aim for the nearby low hills. You will want to walk along their base, keeping them on your right. GPS is useful but not necessary. Walk across a wide sandy wash and into flat creosote desert. At 0.5 mile (0.8 km), keep a small granite rock outcrop to your left and the hills on your right. There are the faint remains of an old camp, with bed springs and cans, in amongst the boulders to your left. I believe this could be an old prospector’s camp.

Continue on to the arrastra by heading downhill into a little valley. Catch up with a small sandy wash and start looking for the arrastra on the hillside directly in front of you. If the canyon starts to narrow up, you have gone too far. The arrastra is to the right (east) of the wash, a short distance up the hillside. Small mine diggings are above it and there are more in the area.


Pinto Wye Arrastra.gpx

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Last Updated on May 21, 2021 by Guy Starbuck