The Rock Wall of Texas

by Brian Dunning
October 15, 2024

The city and county of Rockwall, Texas did not get its name by accident. It is known for what appears to be an enormous system of walls made from stone bricks, nearly all buried underground; such that if you try to excavate for construction there's a solid chance you may run into one of these. Many locals are consumed with trying to figure out who built these walls and why. Was it the earliest Native Americans, or perhaps even a much older civilization that predated them? Or is there some other explanation for this region covering some 50 square kilometers, laced with these enigmatic buried stone walls? Luckily, today we have Skeptoid on the job.

The walls are of varying height, often several meters. Their thickness can be up to half a meter, usually less, and sometimes as thin as a few centimeters. The walls' length has been harder to establish since they're buried, one would need to do a lot of excavation to follow them. Although they're sometimes described as a single wall that encircles the city of Rockwall, that's not the case; they are segments only, found throughout the region, and aligned randomly in all different directions. They appear to be masonry walls made of rocks cut into large blocks, usually the better part of a meter in length and perhaps a couple of hands high, set in a reddish mortar. Most strangely, there is no historical record of any civilization who may have built this most curious structure.

The rock walls' history goes back all the way to 1851, ten years after the first settlers arrived in the region. The story is told best in a 1932 issue of The University of Texas Bulletin:

One of the group, T. U. Wade, while digging a well on the east side of the valley of the East Fork of Trinity River near the western edge of the present townsite of Rockwall, discovered a wall made of jointed sandstone blocks. Because of the strikingly artificial appearance of the wall, current opinion held that it was built by a prehistoric race. Both the town and county of Rockwall derived their names from this wall.

And other similar walls were discovered in the neighboring area. Perhaps the best paper I've seen on the history of human knowledge of the rock wall was published in the journal Field & Laboratory in 1950 by a geologist from Baylor University named John Napier Monroe. He writes that in 1874, the first recorded scientific visit to the walls was made by Richard Burleson, an Assistant State Geologist for Texas. He found that they were igneous dikes, formed when magma flows into an existing vertical fracture and fills it. Various stresses fracture that new igneous rock in both the horizontal and vertical planes, causing the blocklike appearance. The softer outer rock eventually disintegrates and is replaced with sediment, leaving – apparently – a buried rock wall.

Then in 1901, the prolific Texas geographer Robert T. Hill, in the employ of the US Geological Survey, identified the walls as clastic dikes. A clastic dike is when a sedimentary material fills the fractures and later hardens into rock such as sandstone.

In 1909, another geologist from the US Geological Survey, Sidney Paige, concurred with Hill's clastic dikes, and writing in the journal Science, added that there were problems with the view that these were human made masonry walls:

In a photograph at hand exposing a portion of the dike near Rockwall, it may be seen that many of the vertical joints occur above each other, i. e., they are not broken, which condition would not exist in a wall constructed by hand. It may also be noted that the curve to the upper surface of one block exactly fits the curve on the under surface of the next block above, which leads to the same conclusion. The weathered sands between the joints, stained with iron oxide, have been mistaken for mortar.

So it would have seemed like the matter of these walls being artificial masonry structures had been thoroughly debunked. And among scientists, it was. But the general population of the world does not get its information by digging through the annals of The Bulletin of the US Geological Survey. In this case, they got their information from a – well, let's just say a more colorful source.

Just as we have Graham Hancock and various other pseudoscientists vomiting foul fake history all over us today, they had the same more than a century ago. In this case it was a man who would have been a star on Ancient Aliens if it had existed then. The Hungarian American Francis Victor Kuhn was born in Mexico City in 1896. Unlike his counterparts today, he actually did study archaeology at the University of Geneva, and in his twenties, worked on excavations in Carthage. But upon abandoning academia early, he turned his life in a whole new direction. He adopted a new name and persona, calling himself the Count Byron Khun de Prorok. He began traveling everywhere with a cameraman, starring in his own newsreels, always wearing a pith helmet and clad in all the trappings of the trade. He published mass-market books with fantastical titles: Digging for Lost African Gods, In Quest of Lost Worlds, Mysterious Sahara. The New York Times often gave him full page articles promoting his books and discoveries, among them one titled "The Strange Discoveries of Count de Prorok". The Count, as he preferred to be called, fueled all this publicity with more expeditions, always in pursuit of something legendary and generally nonexistent, most notably a lengthy search for King Solomon's Mines, a temple belonging to Alexander the Great, the Biblical land of Ophir, and of course, Atlantis, which he claimed had been in North Africa. Today the Count is regarded as a tomb robber of the very worst kind, having never hesitated to steal sacred human remains and other artifacts, often illegally, to sell to Western museums.

And so, when the Count arrived in Rockwall in 1925, he was quick to prove those meddling scientists and historians wrong. The Dallas Morning News reported that he "shook his head dubiously over the pronouncements of the geologists." He said "I have seen walls like this in the East, and they didn't prove to be natural formations."

Today virtually any literature about the rock wall cites the Count's declaration as a legitimate archaeological statement. A widely syndicated article in 1936 stated "Among the geologists who believe that the wall is man-made is Count de Prorok, who visited Rockwall 10 years ago and declared that it is certainly the work of man." Even today, the Rockwall County Historical Foundation's website says "Count Byron de Prorok examine[d] exposed sections of the walls and conclude[d] they were constructed by a prehistoric race."

But of course, the Count was not a geologist, and his whole career shows that he was always far more interested in showmanship and sensation than in historical fact. After his visit to Rockwall, his comments renewed interest in a news story from 40 years earlier, when local papers claimed someone had found the skull of a giant:

While at work last Saturday, Ben Burton unearthed with his plow, a gigantic skull, fully as large as a halfbushel. The staring sockets wherein the eyeballs once rolled, were as large as a half-gallon cup. Some few of the jaw-teeth still remained; one of them about an inch thick by two inches long. This goes to prove that this county was once inhabited by a race of people that would be wonderful to look at now.

The story, which was from 1886, was one of countless such claims of unearthed giant skeletons and skulls that decorated 19th century pulp news – I covered a lot of these in Skeptoid #144 on strange skulls. Like the rest, no evidence of this skull was ever produced except the news story; and a followup article went on to claim that half the town returned to the site of the find, dug further, and found a magnificent underground palace. But the skull story was enough to ensure that most articles about the wall today include – at least in passing – some claim that some people believe the wall may have been built by a race of ancient giants.

The attention was sufficient to prompt the producers of A&E Networks' show America Unearthed to cover the wall in 2013, a series dedicated to pseudoarchaeology claims throughout the Americas. For the season 2 episode "Great Wall of Texas", the production went to Rockwall and performed their own excavation of one segment. Host Scott Wolter brought in Dr. John Geissman, a professor of geosciences at the University of Texas, and vice president of the Geological Society of America. Geissman knew an easy way to settle the whole question of whether the wall was natural or artificial. The answer lay in paleomagnetism. Before solid rock is formed, any molecules that are magnetic dipoles are aligned with the Earth's magnetic field, and once the rock solidifies they become locked in place. If you cut that rock out and move it – say, to stack it in a wall – it will no longer be in its original magnetic orientation, and we can measure that. When sediments filled the fractures in the original Rockwall bedrock, those molecules oriented themselves naturally; so if we check the magnetic orientation of every block in the wall and find that they're all exactly the same, we know for a fact that that entire structure is one natural formation, and was not manually assembled piecemeal – either by giants or by anyone else. This had been done with the Texas rock wall before, but never on TV in front of a national audience. And can you guess what Geissman found? The same thing that every other geologist had ever found: the rock wall is a natural rock formation, a common clastic dike. (Side note: since the Earth's magnetic pole moves, paleomagnetic data is one line of evidence that can help us date certain rocks in certain circumstances.)

Should you happen to visit the Rockwall County Historical Society, you'll find a section of wall reconstructed from stones removed from an actual excavation. It's the only view of the wall anywhere that you're likely to get, since all the known segments of wall are underground and located on private property. The museum's section on display is nice big chunky blocks, representative of the most compelling sections of wall that have been photographed during excavations. And to their credit, they acknowledge that the scientific analysis is pretty clear that these are simply clastic dikes of the same type found in countless places all around the world. But they still give you enough to let you enjoy the local story. It's a great story, in that it gets people interested in following a thread that leads to a cool science conclusion that's probably new to them. And stories that lead us to science are the ones most worth celebrating.

Special thanks to Skeptoid's in-house geologist, Andrew Dunning, for his invaluable assistance with this episode.

By Brian Dunning
Follow @BrianDunning