Geology Tour Road

Full Loop ♦ Main Index

Towers of Uncertainty, stop 3 on Geology Tour Road

Towers of Uncertainty, near stop 4 on Geology Tour Road


Geology Tour Road Preview (this page)

Main 3D Galleries

Towers of Uncertainty

The Lost Pencil

Virgin Islands

East Virgin Islands

Balanced Rock

Malapai Hill

Squaw Tank

Pleasant Valley


HAVING COMPLETED their morning 3-mile pictograph stroll in Queen Valley, your inveterate duo, E! & Murbachi, decided to do the full loop drive down Geology Tour Road, since Big Blue has 4WD “just in case” the roughest section across Pleasant Valley gets mean. We had several hours’ daylight left. We made use of it, finishing Murbachi’s 3D tour d’ geology with twilight shots athwart the picturesque Virgin Islands. See Elliot’s journal of the drive HERE.

An extract from Patty Furbush’s “On Foot in Joshua Tree National Park” describes the route:

“The Geology Tour Road is an eighteen-mile (round trip) dirt road. A pamphlet, available at the beginning of the road, interprets the geology of the area. Numbered markers at pullouts along the road correspond to numbers in the pamphlet. The road travels from Queen Valley down a long alluvial fan to a one-way loop around Pleasant Valley… Four-wheel drive vehicles are recommended, especially for travel on the lower section of the one-way loop. However, if the roads are dry, two-wheel drive vehicles can usually travel the entire road without difficulty.”

(Click the map & photos below the map to enlarge. Note that an extensive mountain-top 3D photojournal of the area traversed by the Geology Tour Road can be seen in the Lost Horse Mine Loop Trail Galleries)

2D Images


THE SUBJECT OF INSELBERGS often comes up in polite dinner conversation. Like other stand-alone Joshua Tree formations in the Park, along the Geology Tour Road these large rock piles are called inselbergs.

Rock islands, these are—borrowing from the German and from usage of “ice bergs” to describe floating chunks of ice. The Geology Tour inselbergs do, indeed, seem to float serenely upon the landscape.

Jerry’s Quarry – The Definitive Inselberg

Typical Inselbergs along The Tour

  •  Use glasses to view 3D Anaglyphs
  • Click to Enlarge Photos

2D ♦ 3D Anaglyph ♦ 3D Half Side-by-Side

Now we’ve got the inselbergs sorted out, on to the plains. The base of the valley—which stretches 8 or more miles down from Queen Valley to the pretty (and pretty dry looking) Pleasant Valley—consists of granulated granite matter sprinkled with typical dark green & brown desert foliage. The spindly green stuff in the third row is creosote. The little black bushes in the second row are called, curiously enough, black bush. They liven up after a good rain, quickly sprout leaves, flower, drop seeds, and hibernate again.

Joshua Trees, a form of yucca, while not dense or mighty in these parts of JTNP, are nonetheless scattered around. Below is one that grows in a family setting near pullout 7 “Malapai Hill” on the Geology Tour Road. I found it to be especially suited for 3D. How could I not? I have called it “Josh” to insure privacy. (360ft high Malapai Hill rises behind.)

Ideally Placed Joshua Tree

2D ♦ 3D Anaglyph ♦ 3D Half Side-by-Side

Mojave yuccas are the standard yucca found in the Park, with their needle-sharp ends and hair-covered fronds distinguishing them from hairless and more delicate nolinas, or beargrass as it is sometimes called. Silver chollas, too, are present along the Tour road. But you will find no golden or “Teddy Bear” chollas in this area of the park. They are mainly in the hotter region of the lower, Colorado Desert elevations of Joshua Tree. Link to Cholla Cactus Garden.

The Geology Tour traverses the Mojave Desert end of the park, as you drive down a long, steepening descent. From Park Boulevard at 4300ft altitude, the graded dirt road reaches 3200ft once you round the bend and cross Pleasant Valley playa.

The following map and pictures were taken from high atop Lost Horse Mine loop trail when E! and I visited the Lost Horse Mine, and at ground level on this tour.

The second picture row gives readers a sense of scale. Volcanic Malapai Hill dominates here, with the low Hexie Mountains beyond. At the sharp bend in the road, Squaw Tank. Squaw Tank is another of the many small dams built by the earlier 19th century ranchers who ran cattle in what later became Joshua Tree National Park. The National Park was established in 1994. Next lie Pleasant Valley and the flat dry lake bed or playa. After a heavy rain, a shallow lake forms on the playa. Any runoff exits Pleasant Valley down through Fried Liver Wash and out into Pinto Basin in the gap beyond. Yes, Fried Liver Wash. (Click photos to enlarge)


Pleasant Valley & Pleasant Valley Playa

2D ♦ 3D Anaglyph ♦ 3D Half Side-by-Side


3D Anaglyph Gallery I

Park Blvd. to Sandy Wash

The Sandy Wash—pullout #3 on the Geology Tour Road—includes one of the many broad swathes that drain the alluvial plain. Thunderstorm runoff works its way down the slope into Pleasant Valley after first swinging out beyond the western edge of Malapai Hill. It eventually funnels through Fried Liver Wash into Pinto Basin. Included in this first gallery are several pictures I took of the Towers of Uncertainty. You can see its location on the first map above, the one listing the named rock piles or inselbergs.

Many visitors to Joshua Tree have only one day to view the sights. An out-of-the-way place that I like visiting is right here at Stop #3, the Towers of Uncertainty. If you have half an hour free to walk over to the Towers, I encourage you to enjoy their quiet serenity. I have included a few shots in this group on what would be my first trip into the Towers area. For a much more detailed journal of Towers of Uncertainty, click my Towers Home Page. You may be surprised what you will see! Also, for descriptions of the Stops on the Geology Tour Road, head over to Cali49’s page HERE.

(Everyone is invited to download and share pictures on these pages. Click images to enlarge. 1080p resolution. Or Windows users, right-click and choose SAVE LINK AS.)

Murbachi in a zen moment of uncertainty


3D Anaglyph Gallery 2

Erosional Level to Rock Sculpture

Included in this mixed grid pattern are Stops 4 to 6 on the Geology Tour (which Cali49 describes in clear unadorned colloquial English). It seems that in times past, and not so long ago by historical reckoning, Joshua Tree’s soil level was higher than it is now. The climate was wetter, and  amenable to forming topsoil with many more plant species than today inhabiting the park’s upland desert conditions.

Geology Tour 20131111 3DA 1080p DSCF8143The scooped out line in this rock, for instance, indicates an earlier soil surface thousands of years ago. Click to Enlarge →

Stop 5 and the photographs illustrating the various rock piles or inselbergs I have talked about, are about midway in this gallery. From ground level you will see way off in the distance the various groups that rock-climbers have given names to, such as the aforementioned “Towers of Uncertainty.” They are, from north to south, “Island in the Stream,” “The Galapagos” (with five named inselbergs), “Rocky Marciano,” “Jerry’s Quarry,” “Skyscraper Rock,” “Harry’s Quarry,” “The Lost Pencil,” “Virgin Islands,” “East Virgin Islands,” and finally the “Solomon Islands.” All have equally colorful sounding “routes” against which the climbers test their skills.

For onsite close-ups of several of these in the warm afternoon sun, please visit my Lost Pencil gallery.

The final group of pictures in this section contains Stop 6 at the Virgin Islands with a large “rock sculpture” rectangular boulder among other photogenic stuff. I plan to spend an entire day at the Virgin Islands/East Virgin Islands area one day soon, to do them properly in 3D.

E! and I finished our Geology Tour at sundown, back at the Virgin Islands. This is where I got some pretty fine looking silhouette pictures of the Joshuas against the Virgin Islands rock piles. But you will have scroll down the page to Gallery 6 to see those 3D images. Links are provided at top and bottom of this page to more extensive coverage of the Balanced Rock at Malapai Hill and Squaw Tank area. As Alec Guiness says, playing the butler in the comedy spoof movie Murder by Death, “All in good time!”



3D Anaglyph Gallery 3

Malapai Hill & Balanced Rock

(Click link for more extensive Balanced Rock Gallery and Malapai Hill Gallery)

View of Malapai Hill from Squaw Tank area

Malapai Hill


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Click to Enlarge Photos


3D Anaglyph Gallery 4

Squaw Tank

(Click link for more extensive Squaw Tank Gallery)


Concave hollows and pits, called tafoni, a Corsican term for honeycomb structures, are common on rock surfaces in Joshua Tree Granites. This large boulder at Squaw Tank shows considerable erosion. Note the variation in sizes and depths of the pits, a geological puzzle.


3D Anaglyph Gallery 5

Pleasant Valley

Around the bend into Pleasant Valley and the first item on the agenda is an area with some Native Rock etchings or petroglyphs, which E! found within moments of alighting from Big Blue. He has a knack for spotting things like this. Murbachi would, on the other hand, still be searching in 3D. E! then thought it would be a fine thing to go for a stroll up the rocks!

Pleasant Valley Petroglyphs

Pleasant Valley Playa, some old mining ruins, and a Golden Hour view back up the long Geology Tour slope

This area has remnants of the Galena & Gold Coin Mines, which had their day and then were abandoned. E! has written an account of it HERE. Which puts me in mind of a famous line attributed to Mark Twain: “A gold mine is a hole in the ground with a liar on top.”


3D Anaglyph Gallery 6

Virgin Islands Twilight

(Click to Enlarge Photos. Virgin Islands Gallery and  East Virgin Islands)


3D Half Side-by-Side Gallery

(Suitable for 3D TV viewing. Half Side-by-Sides avoid the minor Anaglyph anomalies that can occur. Click images to enlarge. 1080p resolution. Or Windows users, right-click and choose SAVE LINK AS.)



Continue to extended Galleries

Balanced Rock

Squaw Tank

Malapai Hill

Virgin Islands


Thank you for visiting the Geology Tour Road galleries. Now you can amaze people the next time you dine in a Corsican Restaurant by telling everyone about tafoni.



Posted 2014 Oct 28

Updated 2017 Nov 10

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