On the unity and origin of the Australasian tektites

Abstract

Aerodynamic experiments with tektite glass demonstrate that, subsequent to the termination of ablation, high thermal stresses are formed within a thin outer shell. This shell spontaneously spalls, leaving a core shaped like many of the tektites found in Billiton, Java, Philippines and Australia. Certain tektite fragments from Java and Australia are shown to have the same internal stress patterns as pieces of aerothermal stress shell. The over-all evidence indicates that the Australasian tektites descended into the atmosphere as rigid objects of glass. Core shapes found in the extreme southwest part of Australia surprisingly are more like those found in the Philippines than in other areas of Australia; comparisons of chemical analyses and of specific gravity population polygons reveal the same striking circumstances. It is concluded that all Australasian tektites represent a single event. A study of tektite forms, in relation to results from laboratory experiments, indicates that the temperature of formation of primary shapes varied progressively across the Australasian strewnfield. The sculpture on certain australites provides a record of tumbling during entry into the Earth's atmosphere. The effect of turning on the determination of entry trajectories is discussed, and new evidence is presented pertaining to the deceleration which existed when ablation terminated on the australites. The trajectory determinations correspond to an origin from the Moon. Numerous trajectories from the Moon to Earth have been studied with a high-speed electronic digital computer. The relative probability of such trajectories is about 1 200 for the Moon as a whole, and 1 60 for certain crater locations. A comparison of the geographical spread of the Australasian tektites with the Earth landing patterns for lunar material ejected within the a zimuthal dispersion observed of lunar rays, and within the elevational dispersion measured in hypervelocity impact experiments, indicates mutual compatibility.