450 TEKTITES Figure Ablated spherical australites that have lost all but a small relic of the splash form sphere, due to flowage of melt on ablation to the enlarged flange This type of tektite is found only at Port Campbell, Victoria at the extreme distal end of the strewn field Photograph by G Baker; reproduced with permission from McCall GJH (2001) Tektites in the Geological Record: Showers of Glass from the Sky Bath: Geological Society Publishing House immense shock pressures of 100 GPa occurred during impact explosion processes accompanied by temperatures of up to 50 000 K Thus arguments related to requirements for high temperatures in glass technology, which have been advanced to refute terrestrial impact generation of tektites, are invalid, because the temperatures involved in impact processes are many orders greater than had been thought Related Occurrences Libyan Desert Glass and Mount Darwin Glass Anomalous natural glass objects have been found in an area in the extreme south-west of Egypt Irregular masses weighing up to 800 kg strew the desert in interdune corridors These objects are highly siliceous, lechatelierite-bearing glass, quite unlike tektites in that they contain 98.2% silica They seem to be ejected impactites formed of Nubian Sandstone, thrown out Figure An ablated discoidal tektite with a weakly developed flange from a grab sample in the Central Indian Ocean Photo graph by BP Glass; reproduced with permission from McCall GJH (2001) Tektites in the Geological Record: Showers of Glass from the Sky Bath: Geological Society Publishing House