Gas Domes in Ocotillo Wells SVRA

Although the bubbling mud pots of Gas Domes are the star attraction in this trip, the route to this site passes through some unique desert scenery that is unlike other parts of Anza-Borrego.  The terrain here is made up of many small hills that are topped with drifting sand.  In some places, there are odd-looking rocks that are similar to the concretions of the Pumpkin Patch but not quite as rounded. 

When we visited in 2015, there were two gas domes to see and they were about a quarter of a mile from each other.  The first one we came across just popped up on the Earth’s surface in 2002.  The second, primary gas dome has been “erupting” for many decades.

The younger gas dome is conveniently located along the road leading to the older gas dome.  It is located inside a small fenced-off area and there are two signs near the fence that describes the science behind the gas domes.  When we visited, only a few bubbles were emerging from this younger gas dome so it was more like a muddy pool of water as compared to the distinctly bubbling mud of the older gas dome.  It also seemed that there was an even newer gas dome developing just outside the fence near the road.

Even before you reach the younger gas dome, the fenced-off area of the older gas dome can be seen in the distance as it sits on a high hill to the left of the road.  Just before reaching the older gas dome, there is a small picnic area with restrooms.

Because the Ocotillo Wells SVRA allows motorcycles and dune buggies to roam freely here, there is fencing used to funnel vehicles into a logical area near the gas dome so that it is protected.

The older gas dome is similar to a mud pot that you would see at any geothermally active site, such as Yellowstone or Lassen National Park.  The consistency of the liquid in this dome is more like mud, is grey in color and is constantly erupting bubbles.

The hill that the older gas dome sits on also offers a great view of the surrounding desert.  You’ll be able to see this uniquely different part of the Anza-Borrego desert in all directions.  The Salton Sea is very visible to the east.

The Gas Domes are located in the Ocotillo Wells State Vehicular Recreation Area which is next to Anza-Borrego Desert State Park. There are several ways to get to Gas Domes but the easiest and most direct way is by taking our route which starts at the junction of Hwy 78 and Pole Line Road.  For other routes, refer to a map of Ocotillo Wells SVRA. 

The junction of Hwy 78 and Pole Line Road is easy find.  You’re getting close to it when you see an electrical substation with many power lines on the south side of the road.  There are several brown informational signs at the beginning of Pole Line Road here,

To get to our starting point from Hwy 86 (in the east near the Salton Sea), turn west onto Hwy 78 and go 7 miles to Pole Line Road and turn right (north).  To get to our starting point from the west, such as Ocotillo Wells or Borrego Springs, take Hwy 78 to Ocotillo Wells.  From the junction of Hwy 78 and Split Mountain Road, continue east on Hwy 78 for 9.2 miles to Pole Line Road and turn left (north).

Once heading north on the dirt of Pole Line Road, it will become obvious that it is a well-used road.  Remember that you are in a vehicular recreation area, which means there are people driving non-street legal 2 and 4 wheel vehicles randomly in all directions.  Many of the drivers are under driving age so always be on the lookout for traffic in all directions.

Pole Line Road goes through many sections of soft sand so it’s a good idea to engage your high-range four wheel drive after you leave the pavement of Hwy 78.  This will help you be prepared if you come across a patch of soft sand.  Remember that it’s important to keep up your momentum when driving through sand.  Once your vehicle stops, it is difficult to get it going again.

From the junction with Hwy 78, go north on Pole Line Road for 5 miles.  You’ll go over several hills that may have some tricky conditions.  Some are covered with accumulated sand and can be soft so you’ll want to approach them with plenty of momentum.  Some, however, have blind summits, meaning you can’t see what’s coming in the other direction.  Be sure to pay close attention to opposing traffic while navigating these sandy hills and keep on the right side of the road as much as possible.

At the 5 mile mark, there is a restroom on the left side of the road.  Look for a road that goes to the right and turn onto it.  This road might be signed Gas Dome Trail. 

Continue on Gas Dome Trail for one mile.  First you’ll see the fencing of the older gas dome on top of the hill in the distance but you’ll actually come across the younger gas dome first.  Look for it alongside the road on the right.

• See directions to trailhead on Google Maps

Like so many geologic features in the Anza-Borrego, Coachella Valley and Salton Sea areas, the cause of the gurgling Gas Domes is a result of the San Andreas Fault Zone.  Keep in mind that this fault zone is a major tectonic boundary on the Earth’s surface, with the North American Plate on the east of the boundary (on the east side of the Salton Sea) and the Pacific Plate on the west.

Tectonic boundaries or faults, in general, force the land masses on either side of them to do one of four things.  They are:

• Subduction: when one land mass goes underneath another.  This often creates volcanoes such as the Cascade Mountains in the northwestern United States.
• Strike-slip: when two land masses slip past each other.  This is what the San Andreas Fault does north of Palm Springs, California.
• Compression: when two land masses push against each other, such as where India smashed into Asia.  This resulted in the mountain building event creating the Himalaya Mountains.
• Spreading: when two land masses are pulling away from each other.  This results in the thinning of the Earth’s crust which is what is occurring in the center of the Atlantic Ocean.

Along most of its length in California, the San Andreas Fault manifests itself as a strike-slip fault.  However, south of the Coachella Valley (Indio), it switches to spreading action.  This spreading action is what is happening in Anza-Borrego.  It is this very spreading that caused the land to sink, creating a low spot for water to collect and, in turn, created the Salton Sea.  Even the San Joaquin and Coyote Faults, the major fault zones that pass just east of Borrego Springs, also switch to spreading here and have caused the sunken land that has created Clark Dry Lake.

It is this same spreading action that results in a thinning of the Earth’s crust and allows hotter magma to come closer to the surface.  Evidence of this heat shows up in underground water and is the reason why several geothermal power plants have been built along the shores of the Salton Sea.  There are also several more active “mud pots” on the east side of the Salton Sea that erupt more violently and spew out hot mud.  Along with increased earthquake activity, geologists for years have been predicting some type of large volcanic activity to occur in the Salton Sea region because the Earth’s crust is so thin here, making it easier for molten magma to reach the surface.

When pondering how the Gas Domes came to be here, you have to think about all the dynamics that are going on with the faulting action here.  This region is definitely geologically-active and alive!