Desert glass

Desert glass

by Evelyn Mervine

Ancient atomic residue, or evidence of a meteorite impact?
Many kilometers south of Cairo and west of the fertile Nile valley there are mysterious deposits of yellow-green glass among the sand dunes of the Libyan Desert. This Libyan desert glass, as the substance has been named, was discovered in 1932 by Englishman Patrick Clayton, a geologist who was conducting a survey of the Egyptian desert. Clayton must have been surprised when the tires of his jeep first crunched over a piece of glass.

The fifty kilograms of the glass that Clayton carried back with him mystified and enchanted geologists for generations. Libyan desert glass is transparent to translucent and often contains trails of small bubbles, wispy white deposits, and black swirls. There is nothing else, geologically, quite like it. When fairly pure, the yellow-green glass has a gem-like quality. Indeed, two geologists recently spotted a sample of Libyan desert glass among the jewels of King Tutankhamen at the Egyptian Museum in Cairo. The glass had been carved into the shape of a scarab, a central jewel in a large breastplate. The jewel had previously been classified as chalcedony, a type of quartz.

Unfortunately, the region where the glass samples are found is not an easy place to access. The desert glass is nestled between 100-meter tall sand dunes in a very remote part of southern Egypt. After the 1932 discovery there were only two other expeditions (both in the 1930s) to the region until 1971, when three scientists spent two hours collecting only twenty-four samples. During this brief visit, the scientists discovered the remains of a downed Egyptian aircraft and the bodies of nine men. The plane had crashed three years earlier. Clearly, the remoteness of the site makes scientific study of the desert glass somewhat challenging.

Over the years, many theories have been put forth explaining the origin of Libyan desert glass. Researchers have proposed that the glass formed at the bottom of a giant volcanic lake, formed as the result of a meteorite impact, and formed because of the detonation of an ancient atomic bomb built by aliens.

Hang on a minute. Let’s play a quick game of which explanation doesn’t belong. Or, to put it another way, let’s find the woo-woo speak. I’m going with the aliens and the ancient atomic bomb. What’s your choice?

Believe it or not, I ran across a not one website but several promoting the ancient atomic warfare theory. I ran across the sites one day in the school library, where I was surfing the internet looking for some information on natural glasses. Earlier in the day in my mineralogy class, I had learned about tektites, high-silica glasses which are believed to form during meteorite impacts but which scientists do not fully understand. I became curious and decided to do a little research on the chemistry of tektites and some of the theories for tektite formation.

One website actually used Biblical quotations to justify the atomic warfare theory for the origin of tektites. The site claimed that descriptions of devastating warfare found in the Bible resembled descriptions of the destruction caused by atomic bombs at Hiroshima and Nagasaki. There was evidence, the site claimed, for ancient atomic explosions in not only Egypt but also in Scotland, Turkey, and India. Of course, the ancients weren’t smart enough to figure out how to build atomic weapons on their own. Thus, aliens played a key role in these ancient atomic wars.

If this theory sounds like something that the famous pseudoarchaeologist Erich Von Daniken might dream up, it is. In his 1969 book Chariots of the Gods Von Daniken claims that Sodom and Gomorrah, the biblical cities of sin, were destroyed by ancient atomic bombs. More recently, a writer named David Childress has been promoting the ancient atomic warfare theory. Childress has written such classics as Extra Terrestrial Archaeology (1994) and A Hitchhiker’s Guide to Armageddon (2001). He discusses his evidence for ancient atomic warfare in the book Technology of the Gods: The Incredible Sciences of the Ancients (2002).

Childress uses the Libyan desert glass as evidence that atomic bombs were detonated in ancient times. It isn’t worth your time or money to order Childress’s book or, even, to check it out of the library. However, a recent article titled “Ancient Atomic Warfare” written by Childress and published online at a site called NEXUS (a site known for promoting far-fetched conspiracy theories and other pseudoscientific nonsense) sums up Childress’s theories nicely, I believe. The article can be accessed here  .

I won’t attempt to address all of the “evidence,” such as vitrified forts, that Childress claims proves that atomic bombs were detonated in ancient times, but I will address the mystery of the desert glass. As a geologist, I can confirm that scientists are still figuring out exactly how the Libyan desert glass formed. There are still many gaps in geologists’ understanding of Libyan desert glass, and many of the scientific theories advocated in the past have been modified or refuted. Science is, as always, a process.

Childress and others claim that Libyan desert glass resembles glass that forms when modern atomic bombs are detonated. Indeed, large quantities of glass did form when the first atomic bomb was detonated on July 16th, 1945 in the New Mexican desert. The test was called the Trinity Test and the glassy material that formed was given the name Tritinite and is now greatly valued by rock collectors. While collectors were free to collect samples for many years, the United States government buried most of the Tritinite in the early 1950s and restricted collection of the radioactive glass.

Glass does form when an atomic bomb is detonated in a desert. I question, however, the legitimacy of extending that fact to postulate that the finding of glass in a desert means that an atomic explosion must have occurred there. The Libyan desert glass has been dated by geologists to an age of about 28 million years. Could ancients living 28 million years ago have detonated atomic bombs? Wait a moment. There were no humans living 28 million years ago on Earth. I guess that Childress must be overlooking that fact. Even if Childress didn’t overlook the fact that the glass is very, very old, I’m sure that he could find loopholes to make his theory work. Geological dating is never that accurate anyway, right? Certainly, we geochemists could be off by a few million years. If nothing else, there were aliens around 28 million years ago. They always could have been conducting ancient nuclear experiments in Earth’s deserts, I suppose.

The most reasonable scientific explanation is that Libyan desert glass is a type of tektite, a kind of natural glass with very high silica content. Volcanic glasses, which are fairly common, generally contain 50 to 70% silica content. Tektites, which are much rarer, contain much higher amounts of silica. The Libyan desert glass samples are about 98% silica and resemble man-made glasses more than they do volcanic glasses. For instance, Libyan desert glass, like high-quality artificial glass, is very resistant to heat and does not melt until it reaches fairly high temperatures.

Tektites are believed to form when there is a meteorite impact. Tektites form when the material that the meteorite hits becomes molten and quickly re-solidifies at very high pressures and reasonably low temperatures (compared to the conditions within the Earth at which rocks and minerals normally crystallize). When a meteorite happens to hit a desert, the theory is, the sand re-solidifies. Sandy deserts primary consist of small grains of quartz, which has the formula SiO2. So, it would make sense that if a meteorite were to land in a desert, silica-rich glass would form. In general, glass forms whenever a molten material, such as lava or sand, cools very quickly. Glasses are amorphous because they cool so quickly that the atoms do not have time to arrange themselves in a crystal pattern. Volcanic glasses, for insta
nce, form when lava is quenched by cool seawater or when volcanic projectiles cool quickly in the air.

Unfortunately, there is no obvious meteorite crater near the Libyan desert glass site. Even recent computer analysis of a satellite data cannot detect evidence of a crater. Childress, of course, jumps to conclusions and claims that the lack of evidence of a meteorite crater implies that no meteorite existed.

As a geochemist who is currently studying the properties of mid-oceanic ridge glasses, I am not so quick to jump to conclusions. There may be no sign of a crater, but there is other evidence that the Libyan desert glass was formed by a meteorite impact. For instance, there are high amounts of iridium, an element with low concentrations on Earth but high concentrations in many meteorites, in the Libyan desert glass samples. The white deposit found in many of the samples is cristobalite, a high-pressure polymorph of quartz that is often found at sites of meteorite impacts. Even simpler than this, might it be possible that after 28 million years, it is a little difficult to detect evidence of a crater amidst giant, shifting sand dunes in a very remote part of Egypt?

Even if no crater exists, that doesn’t mean that the glass isn’t the result of a meteorite impact. Even Childress admits that, possibly, the glass formed when a meteorite exploded in mid-air above the desert, a so-called “soft impact.” Childress even mentions a soft meteorite impact that is believed to have occurred in 1908 at Tunguska in Siberia. At Tunguska trees were flattened and a giant explosion was heard for miles and miles, but no crater was formed. Scientists currently believe that a meteorite or a comet exploded (vaporizing, essentially) in mid-air above Tunguska.

A similar soft impact might have occurred above the Libyan desert 28 million years ago. Such an explosion certainly would have been energetic enough to turn much of the desert sand into solid glass. While Childress mentions the Tunguska event, he is quick to justify his description, saying that the soft impact theory is only explained, “as far as mainstream science is concerned. That event, like the pure desert glass, remains a mystery.”

I, for one, prefer the mainstream science.

Truthfully, the origin of the Libyan desert glass is still somewhat of a mystery. Scientists are still studying the unusual chemical and physical properties of this jewel-like yellow-green glass and still debate its origin. Primarily, the debate is over what sort of meteorite and what kind of impact, soft or hard, may have caused the formation of the glass. Some scientific theories, such as a volcanic origin for the glass, have been largely rejected by scientists. The 9000-year-old volcanoes found in the region near the Libyan desert glass are far to young to have produced the 28 million year old glass deposit.

I realize that most people are likely to be inclined toward a more scientific explanation for the formation of the Libyan desert glass than the alien atomic warfare explanation proposed by Childress and others. I am hopeful, at least, that most people who browse these pseudoscientific articles and websites find them amusing, as I did one day when I stumbled across them as I was searching for some scientific articles on tektites.

I have to wonder, though, what inspires such crazy notions and how people such as Von Daniken and Childress manage to sell so many books. Certainly, far more copies of a single one of their books have been sold than, say, all the editions of my igneous petrology textbook, which has some valuable scientific information about natural glasses.

The only sense I can make out of such theories, I suppose, is that they are definite answers to puzzles that have no immediately apparent, comprehensive scientific explanation. The ancient atomic theory provides a comprehensive answer that is also very fashionable. Conspiracy theories are all the rage these days. Even the Tunguska event is heralded by conspiracy theorists as an early test of atomic weapons. I’m sure that Richard Feynman and others working on the Manhattan Project would have been distressed to learn that the Siberians had figured out the atomic bomb in 1908 but kept their knowledge a secret.

Although I am a die-hard skeptic, even I am not immune from indulging in a little paranormal nonsense. For instance, I love watching the X-files. Watching Scully and Mulder attempting to solve paranormal puzzles, however silly, is endlessly entertaining. I can just imagine an episode with David Duchovny, his windswept hair looking particularly sexy, driving a jeep around the Egyptian desert and finding an ancient space ship crash-landed in the sand next to a glass sample. Personally, though, I prefer my dose of paranormal flim-flam where it belongs: science fiction.