For almost 40 years now, the Venezuelan capital has been subject to an unusual phenomenon that scientists cannot fully explain. From time to time, a black substance of unknown origin appears on the streets of Caracas, causing car accidents and killing people. It is called La Mancha Negra, which translates from Spanish as “the dark spot.” Journalists prefer a more intriguing name – “mysterious black slime”.
The Popular Mechanics magazine published an article in which it tried to find the answer to the question of what it is. Possible versions include an oil leak, “hello” from aliens, and a political provocation. Or perhaps something more sinister.
Cars lost control, 1800 people died
“Since 1986, a strange black sludge has been terrorizing the city streets, causing deaths and giving rise to myths,” the popular science magazine begins its article.
The first such spot was discovered in 1986 during the renovation of the highway connecting Caracas with the local airport named after Simon Bolivar. Road workers noticed it. The spot was about 130 feet long and did not cause much concern at first.
But then it began to grow, increasing in size, and by 1992, when Chicago Tribune decided to write about it, it occupied an eight-mile stretch of road. The substance was described as a thick black liquid with the consistency of used chewing gum.
It was reported that since the appearance of this spot, many car accidents have occurred due to its fault, in which 1.8 thousand people died. The cars simply lost control when they found themselves on a section of the road covered with an unknown substance. The sticky mass made the roadway extremely dangerous – vehicles crashed into each other or drove off to the side of the road.
Five years later, the mucus is back
In the 1990s, the black substance had already reached many streets of Caracas. The Venezuelan government has decided to allocate funds to eliminate the mysterious substance. But it was impossible to remove it: the mucus appeared again and again. They washed it off with jets of water, treated it with cleaning agents, removed the layer of asphalt soaked in it and put a new one on top – all to no avail. The stain appeared again.
In an attempt to remove the slurry, crushed lime was used, hoping to dry the surface. For some time this helped, however, it led to the fact that the townspeople began to suffocate from lime dust.
In 1996, the latest German pollution control equipment was brought to Venezuela, and the black spot seemed to be over. But in 2001, the mysterious slime returned. In some places it reached an inch thick on the roads of Caracas.
Theories from sewers to aliens
The strangest thing is that the experts involved could not reliably establish the nature of this substance. Chemical analysis showed that it contained motor oil, brake fluid, dust, and some organic compounds. But where does all this come from?
Various hypotheses have been put forward:
Sewage from slums located on the slopes of the surrounding hills gets under the asphalt; they cause a chemical reaction that causes a slurry to appear on the surface.
Asphalt is of poor quality, which manifests itself in the formation of an oil-like substance.
There are a lot of old cars in Caracas, and oil and other technical fluids are constantly dripping onto the road surface; mixed with dust, they formed a slippery mass.
This mucus was deliberately sprayed on the roads by oppositionists who wanted to tarnish the reputation of Venezuelan President Carlos Andres Perez .
None of these versions have been convincingly substantiated. Given the lack of information, one should not be surprised at the emergence of conspiracy theories. Actually, the last hypothesis – about political provocation – is one of them. It was also rumored that La Mancha Negra was the work of aliens. A kind of attempt to convey some kind of message to humanity.
“There are many myths around this story. The size, scale, time of leakage of this slick, its reappearance – all this has become a real mystery,” Ramanan Krishnamurthy, a professor of chemical and petroleum engineering at the University of Houston, told the author of the article.
Oil or bad asphalt?
As time passed, scientists were left with only two hypotheses. First: black slime – the consequences of poor-quality asphalt (it has already been mentioned). Second: these are traces of oil seeping from underground.
Logically, it would be worth thinking about this first: Venezuela is an oil-producing country. However, scientists see flaws in this hypothesis.
“Usually this kind of seepage from the subsurface occurs at one point, it is unlikely to spread over an eight mile long road. In addition, heavy oil tends to settle rather than try to rise to the surface. So, most likely, the reason is bad asphalt,” says Krishnamurti.
“This is the simplest explanation: the phases of the treated asphalt separated, and one of them “floated” to the surface, leaving a black and slightly greasy stain on the roads,” suggests another researcher, a lecturer in the Department of Petroleum Engineering at the University of Houston, Reynaldo Gonzalez.
But this theory also raises criticism. No matter how bad the asphalt is, scientists cannot explain its strange “behavior.” Moreover, nowhere in other, poorer countries of the world – say, in Africa and Asia – has anything like this been noticed.
So the “mysterious black slime” of Caracas is still waiting for its research, more serious and thorough.