Libyan Desert Glass
Libyan Desert Glass represents an unsolved scientific and geological enigma which is addressed by a Perigee: Zero Impact.
As described on the Glen Avalon web page [http://glenavalon.com/ldglass.html], The enigma of this glass is:
- The amount. It is the largest known deposit of a natural silica glass, ~98% SiO2 , on Earth.
- It's distribution. The distribution is approximately elliptical, ~130 km by ~50 km with the major axis ~NNW by SSE.
- Physical properties. The composition and structure of the glass are consistent with a hypothesis that the glass was formed from melted desert dune sand and subsequently cooled over a period greater than 24 hours in an Earth atmosphere.
- Fusion energy. Possibly a meteorite or comet impact, but there are no meteor craters detectable from satellite photos with a resolution of ~5m within 150 km. No Libyan Desert Glass has been found at the nearest meteorite crater, located in Libya, ~150km to the west.
- Chemistry. The glass cannot have been fused from the local exposed sandstone.
- Age of glass and dunes. The dune sand and dunes have been formed in a time estimated to be less than 1,000,000 years, yet the fission track dates of the glass have a mean of ~28,000,000 years.
- Surface geology. 28,000,000 years ago some geologists estimate that the sandstone was beneath ~300m of limestone and covered with vegetation.
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 riddle of the sand, 10 July 1999, NewScientist.com news service, Giles Wright
Tiny pieces of silica glass are fairly common in nature. When volcanic lava cools suddenly-as red-hot magma pours into the sea, for instance-molecules of silica in the lava freeze at random, creating an amorphous mass that resembles broken glass. But these materials are about 75 per cent amorphous silica at most. The rest is made up of crystals of quartz and oxides such as aluminium and iron. The desert glass is totally different: "It's the purest natural glass in the world," says Vincenzo de Michele, keeper of minerals at Milan's Museum of Natural History, "with a silica content of 98 per cent."
Our hypothesis presents a scenario whereby the components of a nearly pure silicate comet are disrupted across the landscape of earth in a grazing Perigee: Zero impact. While the vast majority of the debris distributed in the form of PZ Eject is excavated terrestrial material, we have identified areas where virtually pure cometary debris was emplaced. The common circumstance seen is immediately after a PZ Terminal event, a residual component of the comet body escapes over the Terminal Crater wall and traverses a sub-orbital arc before being emplaced as a veneer across the landscape. The suspected locations for these nearly-pure silicate strata include the Taklamakan Desert in China, the Dry Valleys of the Antarctic, the Bahama Island emplacement and the Brodeur Peninsula in Canada's NWT. We have expected, but have not found compressed and heated core cometary silicate material within the cratering footprint. [Reference Herkimer Diamonds - but those are anomalies of ejecta emplacement landforms, rather than craters]
A commonly-considered solution to this enigma is a meteor impact or near-by bolide explosion. These solutions call for the local sand to become the primary component of the glass. Since no crater has been found in these area, a solution has not been proven in a scientific forum.
The Perigee: Zero research has identified several major PZ Cratering events in the immediate area of interest. Furthermore, the sites have previously described as "oval", which is the basic PZ Ejecta emplacement shape. the location of the LDS 50 x 80 km Distribution Areas are shown in the graphic below.
Map by Roberto Del Rosso
Using the general map coordinates, we can confidently present the areas as PZ Impact zones. Several large PZ Terminal Cratering events are located within the desert areas. We interpret the southern-most sits as being in a "bruise area". The graphic below presents the area in GE, using a DEM-only overlay to highlight the topography, The PZ impact series responsible for this bruise has not been identified as of yet.
LDM SItes in GE with a DEM overlay
The northern most LDG site lies at the tip of the Qattara fan crater. however, we do not expect that the necessary temperature and pressures would be reached at that particular location directly under the spreading fan debris. Another causal structure is instead more probable, although not yet located.
It is our considered opinion that the Libyan Desert Glass discovered in the Sahara was created by a natural process involving the Perigee: Zero impact cratering of a de-orbiting Taurid Complex comet.
Note: The Google earth Keyhole KMZ file for this presentation is available as LDG.kmz on our KMZ Downloads page.
Link to Wikipedia Desert Glass Page
Link to Discovery Channel Report King Tut's gem may have formed from meteor collision
Link to paper A 2003 EXPEDITION INTO THE LIBYAN DESERT GLASS STREWN FIELD, GREAT SAND SEA,
WESTERN EGYPT." by Koeberl, Rampino, et al. 2003