Message #17367

[Bianca]

Mysterious Glass in the Egyptian Sahara



One of the strangest mysteries of ancient Egypt is that of the great glass sheets that were only discovered in 1932. In December of that year, Patrick Clayton, a surveyor for the Egyptian Geological Survey, was driving among the dunes of the Great Sand Sea near the Saad Plateau in the virtually uninhabited area just north of the southwestern corner of Egypt, when he heard his tyres crunch on something that wasn't sand. It turned out to be large pieces of marvellously clear, yellow-green glass.

In fact, this wasn't just any ordinary glass, but ultra-pure glass that was an astonishing 98 per cent silica. Clayton wasn't the first person to come across this field of glass, as various 'prehistoric' hunters and nomads had obviously also found the now-famous Libyan Desert Glass (LDG). The glass had been used in the past to make knives and sharp-edged tools as well as other objects. A carved scarab of LDG was even found in Tutankhamen's tomb, indicating that the glass was sometimes used for jewellery.

An article by Giles Wright in the British science magazine New Scientist (July 10, 1999), entitled "The Riddle of the Sands", says that LDG is the purest natural silica glass ever found. Over a thousand tonnes of it are strewn across hundreds of kilometres of bleak desert. Some of the chunks weigh 26 kilograms, but most LDG exists in smaller, angular pieces--looking like shards left when a giant green bottle was smashed by colossal forces.

According to the article, LDG, pure as it is, does contain tiny bubbles, white wisps and inky black swirls. The whitish inclusions consist of refractory minerals such as cristobalite. The ink-like swirls, though, are rich in iridium, which is diagnostic of an extraterrestrial impact such as a meteorite or comet, according to conventional wisdom. The general theory is that the glass was created by the searing, sand-melting impact of a cosmic projectile.

However, there are serious problems with this theory, says Wright, and many mysteries concerning this stretch of desert containing the pure glass. The main problem: Where did this immense amount of widely dispersed glass shards come from? There is no evidence of an impact crater of any kind; the surface of the Great Sand Sea shows no sign of a giant crater, and neither do microwave probes made deep into the sand by satellite radar.

Furthermore, LDG seems to be too pure to be derived from a messy cosmic collision. Wright mentions that known impact craters, such as the one at Wabar in Saudi Arabia, are littered with bits of iron and other meteorite debris. This is not the case with the Libyan Desert Glass site. What is more, LDG is concentrated in two areas, rather than one. One area is oval-shaped; the other is a circular ring, six kilometres wide and 21 kilometres in diameter. The ring's wide centre is devoid of the glass.

One theory is that there was a soft projectile impact: a meteorite, perhaps 30 metres in diameter, may have detonated about 10 kilometres or so above the Great Sand Sea, the searing blast of hot air melting the sand beneath. Such a craterless impact is thought to have occurred in the 1908 Tunguska event in Siberia--at least as far as mainstream science is concerned. That event, like the pure desert glass, remains a mystery.

Another theory has a meteorite glancing off the desert surface, leaving a glassy crust and a shallow crater that was soon filled in. But there are two known areas of LDG. Were there two cosmic projectiles in tandem?

Alternatively, is it possible that the vitrified desert is the result of atomic war in the ancient past? Could a Tesla-type beam weapon have melted the desert, perhaps in a test?

An article entitled "Dating the Libyan Desert Silica-Glass" appeared in the British journal Nature (no. 170) in 1952. Said the author, Kenneth Oakley:3

Pieces of natural silica-glass up to 16 lb in weight occur scattered sparsely in an oval area, measuring 130 km north to south and 53 km from east to west, in the Sand Sea of the Libyan Desert. This remarkable material, which is almost pure (97 per cent silica), relatively light (sp. gin. 2.21), clear and yellowish-green in colour, has the qualities of a gemstone. It was discovered by the Egyptian Survey Expedition under Mr P.A. Clayton in 1932, and was thoroughly investigated by Dr L.J. Spencer, who joined a special expedition of the Survey for this purpose in 1934.

The pieces are found in sand-free corridors between north-south dune ridges, about 100 m high and 2-5 km apart. These corridors or "streets" have a rubbly surface, rather like that of a "speedway" track, formed by angular gravel and red loamy weathering debris overlying Nubian sandstone. The pieces of glass lie on this surface or partly embedded in it. Only a few small fragments were found below the surface, and none deeper than about one metre. All the pieces on the surface have been pitted or smoothed by sand-blast. The distribution of the glass is patchy.

While undoubtedly natural, the origin of the Libyan silica-glass is uncertain. In its constitution it resembles the tektites of supposed cosmic origin, but these are much smaller. Tektites are usually black, although one variety found in Bohemia and Moravia and known as moldavite is clear deep-green. The Libyan silica-glass has also been compared with the glass formed by the fusion of sand in the heat generated by the fall of a great meteorite; for example, at Wabar in Arabia and at Henbury in central Australia.

Reporting the findings of his expedition, Dr Spencer said that he had not been able to trace the Libyan glass to any source; no fragments of meteorites or indications of meteorite craters could be found in the area of its distribution. He said: "It seemed easier to assume that it had simply fallen from the sky."

It would be of considerable interest if the time of origin or arrival of the silica-glass in the Sand Sea could be determined geologically or archaeologically. Its restriction to the surface or top layer of a superficial deposit suggests that it is not of great antiquity from the geological point of view. On the other hand, it has clearly been there since prehistoric times. Some of the flakes were submitted to Egyptologists in Cairo, who regarded them as "late Neolithic or pre-dynastic". In spite of a careful search by Dr Spencer and the late Mr A. Lucas, no objects of silica-glass could be found in the collections from Tut-Ankh-Amen's tomb or from any of the other dynastic tombs. No potsherds were encountered in the silica-glass area, but in the neighbourhood of the flakings some "crude spear-points of glass" were found; also some quartzite implements, "quernstones" and ostrich-shell fragments.

Oakley is apparently incorrect when he says that LDG was not found in Tutankhamen's tomb, as according to Wright a piece was found.

At any rate, the vitrified areas of the Libyan Desert are yet to be explained. Are they evidence of an ancient war--a war that may have turned North Africa and Arabia into the desert that it is today?