Glass from space?

The riddle of tektites


Last updated: 10th August, 2006

WHEN FIRST DISCOVERED IN CZECHOSLOVAKIA in the latter half of the eighteenth century, the mysterious, walnut-sized, dark-colored glassy spherules were at first thought to be the mineral olivine, then volcanic glass (obsidian), and finally slag from old glassworks. But such interpretations were scuttled when more stones were discovered over one hundred years later in southeast Asia and Australia that just wouldn't fit any of these identifications.

Further studies indicated that these stones are geological aliens; their chemical composition is invariably quite different from the geological formations in which (or, more usually, on which) they are found. Thus, experts were forced to come to an amazing conclusion: they had come to rest far from where they came into being.

More amazing facts soon came to light; some were found to have tiny internal bubbles containing atmospheric gas at a pressure equivalent to an altitude of 32 kilometers (Bevan Autumn 1992, p. 920). Study of the intriguing symmetrical shapes of stones found in Australia led to the conclusion that they had traveled at great speed in a molten state through the atmosphere, the varying conditions of flight while molten explaining the variety of shapes. The conclusion that they had once been molten gave rise to their name, tektites, from the Greek tektos, meaning “molten”. Some geologists proposed that they were a form of meteorite. But astronomers declared that true meteorites cannot be made of glass. So what could they possibly be, and where did they come from?

Much has been learned about tektites over the years, particularly about their chemical composition. But few natural phenomena have stirred up as much contention or conjured up the word “mystery” quite so often as these small glassy stones. If only Solomon, Israelite king and august scientist, were alive today he would no doubt help resolve some of the questions that continue to dog researchers.

Experts debate whether features of the surface sculpture of tektites should be attributed to conditions when they were formed or to the effects of erosion over the years since their formation. And though more and more experts are coming to the conclusion that they are made from the stuff of our own planet others beg to differ. One day consensus of opinion may be reached. Believers in the divine origin of all of the universe's marvels and mysteries revel now in the bafflement tektites cause the experts but will also, should the mystery be completely solved, continue to delight in their testimony to the genius and power of God. His works are great and bring profound pleasure to those who love Him (Ps. 111:2). Mystery or marvel, we love them all.

Birds and bees of tektites

Tektites are small, often walnut-sized, glassy spherules found scattered in four main concentrated patches known as “strewn fields” in an S-shaped belt over a large area of the earth's surface, from 1. Australia, through southeastern Asia, 2. the Czech Republic and Slovakia, 3. the western coast of Africa (Ivory Coast), and 4. Georgia, Texas and the continental slope off New Jersey in the USA. (The S-shape probably has no scientific significance.) The Australasian field covers 10% of the planet. The tektites in each field are of similar composition and are thought to have been formed by a single event. In addition to these large troves, smaller deposits have been found lying near the surface in the Tasman Sea near New Zealand and on the Caribbean island of Haiti. Then, to “disprove” all the common statements to the effect that tektites are not found in South America, R. S. Harris and P. H. Schultz of Brown University, RI, announced in “Lunar and Planetary Science” XXXVII (2006) that two tektites had been discovered attached to molten glass in Argentina. Where next?

Vltavines from Czechoslovakia

Most tektites are black, some are found in varying shades of green, and a few are yellow or orange. They weigh from one gram up to as much as 8 kilograms.

Muong Nong tektites

In addition to “ordinary” tektites, scientists speak of another kind as “layered”, and give them the disarming name of Muong Nong tektites. These tektites do not have the aerodymically-crafted shapes of “regular” tektites, and are generally larger than ordinary tektites. So far they have been found on only two of the four strewn fields (Australasian and East European). Experts believe they consist of glass that did not travel as far as regular tektites, and are thus located closer to the site of the impact that created them (see below).


Tiny mictrotektites, which are tektites less than one millimeter in diameter, are also found in deep-sea deposits off south and west Australia as well as in the eastern Atlantic off Africa and off the coast of New Jersey in the United States. Off New Jersey, microtektites have been found mixed in with fragments of regular tektites in marine sediments at a ratio of about 50:1 [1% of 51%] (Glass, Koeberl, Blum & McHugh 1998, p. 231). One possible explanation for the distribution of microtektites is that, due to their small size, they were carried further from the site of origin.

The origin of tektites

Four chief theories of their original formation have been formulated: in volcanoes on the moon, through meteorite impacts on the moon, in volcanoes on earth, and through meteorite impacts on earth. Some argue that they come from a more distant objection in the solar system, reaching earth in comets. A few believe they come from material ejected by passing comets, while a few even now, at the beginning of the twenty first century, cling to belief in a lunar origin; some even propose that a Saturn-like ring of tektites of lunar origin once encircled the earth. When the chief proponent of the lunar origin died in 2000, the program at his funeral included the words "Tektitae de luna sunt," which means "Tektites are from the Moon”.

Various australites (Australian Natural History)

Prevailing opinion today holds to the meteorite-impact-on-earth theory, an idea that was met with skepticism when proposed in 1933 by L. J. Spencer, Keeper of Minerals at the British Museum. In this scenario, a high-speed collision instantly turned soil and rock into “glass”, and kicked or splashed bits of the stuff high into the atmosphere and even beyond, the little spherules often returning to earth thousands of kilometers from their birth place. An earthly origin is supported by the telltale sign of their chemical signature: “The compositions of tektites are very similar to quartz-rich sedimentary rocks (such as sandstones and siltstone) that are common on the surface of the earth” (Bevan, p. 922). They also lack the background radioactivity found in meteorites. Probable impact sites have been identified for the tektites of two of the four main strewn fields. Czechoslovakian tektites are believed to come from a 15-mile-wide impact crater at Ries in nearby Germany, while the Bosumtwi crater in Ghana is possibly the source of the African specimens. Impact sites of the Australian and North American strewn fields are proving more elusive, with a crater-like lake in Cambodia suggested as the most likely source of the Australian tektites. The more recently discovered Haiti tektites almost certainly came from the Chicxulub crater in the Yucatan Peninsula of Mexico. (Similar tektites have also now been found in Mexico.)

Whichever theory you choose, they all agree that tektites landed on earth after traveling rapidly through its atmosphere. The generally favored theory is that they formed when rock and soil were instantly melted and turned into glass when the earth was struck by a meteor; the globules were flung high into the air, many shooting above the level of the earth's atmosphere before returning in a rain of glass globules stretching over hundreds of miles.

Putting it as simply as possible, we can say that tektites form when an impacting body produces enormous pressures and sudden intense heating, liquefying soil and rock and sending the melt into the atmosphere. The force of the impact melts the rock and soil and “splashes” it at breakneck speeds — such speed, in fact, that some of it may even exceed the “escape velocity” of about 7 miles per second, and actually escape earth's gravitational field and wander off into space. Other pieces are ejected at varying speeds; some almost escape earth's gravitational field, but not quite, and fall back, reaching almost escape velocity again by the time it slams into the atmosphere. (To understand that point, imagine throwing a ball up into the air as hard as you can. As it goes up, it slows down until eventually it stops completely and then begins to fall back again. By the time it reaches you, it is going as fast as it was when you threw it.) Those ejected with the highest velocity, and thus re-enter the atmosphere at high velocity, betray their long journey by showing signs of having melted a second time; have a characteristic button shape with a flange around the middle that indicates they were partially melted as they re-entered the atmosphere, the molten part at the leading edge being pushed backwards and solidifying as a flange around the tektite's “waist”.

For the more technically minded, the drama can be spelt out in more detail. When a meteorite weighing many tons slams into the earth or the moon, models proposed by physicists tell us that the impact compresses a column of air, water and rock into an extremely hot plasma , an ionized (has electrons removed) gas which is usually considered to be a distinct phase of matter in contrast to solids, liquids, and gases because of its unique properties (Wikkipedia). The dense plasma is blasted out just as powerfully as solid objects would be, and as it goes and cooks, it would condense into glass blobs.

The age paradox

Another tektite mystery lies in the paradox of a disparity between the age of formation of tektites (determined by radiometric methods) and the age of rock strata in which they are found. In some cases, the tektites are older than the strata in which they are found, and in some cases they are younger. The 34 million-year-old tektites in Texas are found in strata that is dated at 45 million years old (Encyclopedia Britannica, “Tektites”), while 700,000-year-old tektites in Australia are found in very young, superficial sediments. These differences have fuelled the debate over the source and history of tektites. Old tektites in young strata are easy enough to explain; no strata have been formed to bury the tektites until very recently. Any tektites formed in a meteorite impact on earth 700,000 years ago and dropped onto the Nullarbor Plain of Australia would still be sitting on top of the ground! No sediments have been deposited over most of that area for a very long time.

Young tektites in older strata are more difficult to explain. One should note, however, that the dating of tektites in Haiti coincides precisely with the dating of strata in which they are found, both figures coming out at 65 million years.

To this day, much mystery surrounds this fascinating phenomenon. Such mysteries do not prove the existence of God, but they should help us grasp the boundless ingenuity of the Great Creator who brought all such mysteries into being.

References and notes

Bevan, Dr. Alex Autumn 1992, The Day it Rained Glass, Australian Natural History

Glass, B. P., Koeberl, J. D., Blum, J. D., and McHugh, C. M. G. 1998, Upper Eocene tektite and impact ejecta layer on the continental slope off New Jersey, Meteoritics and Planetary Science 33, 229-241

Further reading

Dawn to Dusk publications

Other printed material

On the Web

McNamara & Bevan: Tektites

O'Keefe: Tektites and their Origin (very expensive)

Barnes & Barnes: Tektites


Geoscience: Tektites


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