Geologists Hear Address On Origin Of Tektites

Press, Volume CII, Issue 30269, 23 October 1963, Page 18

Geologists Hear Address On Origin Of Tektites

The origin of tektites was discussed in an address by Dr. S. R. Taylor, professorial fellow in the department of geophysics at the Australian National University, Canberra, to the Canterbury branch of the New Zealand geological Society last evening.

Tektites are black, glassy spheres of about one inch in diameter, found only in a few restricted areas but in numbers running into many thousands Their shape and composition make it almost certain that they arrived in their present locations after passing through the earth’s atmosphere, but scientists are divided over whether they originated on the earth or on the moon. The lack of any evidence that tektites were ever exposed to cosmic rays for any length of time makes any other origin extremely unlikely. Dr. Taylor attended a world conference on tektites at Pittsburgh, Pennsylvania, last month. The conference was split about half and half between a lunar and a terrestrial origin for the tektites, he said, moat of the aerodynamic specialists favouring the moon as the origin, while the geologists were almost unanimously in favour of the earth origin theory, which he himself supported. There was general agreement, Dr. Taylor said, that the tektites were splashes resulting from the impact of a meteorite or asteroid or the head of a comet on the surface of the earth or moon. The composition of the tektites was that of k typical surface sediment of the earth, and this was one of the main arguments against a lunar origin, since the surface of the moon was thought to be quite different. “Only a sample of the moon’s surface could finally clear up this point, but if the composition of the surface materials turns out to be

in fact very similar to that of the earth’s surface sediments, our whole theory of the origin of the moon will have to be revised,” said Dr. Taylor.

Dr. Taylor favoured the head of a comet rather than a meteorite or asteroid as the ultimate cause of the tektites, since a comet head would explode well above the surface, as had apparently happened over Siberia in 1908. Data just released by the Russians revealed there was a circle of standing trees in the centre of the huge devastated area produced by this event; no crater was left as would have been the case if a meteor had fallen. This would help to explain why no crater could be linked to any of the three known tektite groups. The absence of any anomalous amount of iron or nickel in the tektites made it extremely unlikely that they were the result of the impact of a metallic meteorite, or asteroid, and stony meteorites were not known to produce large craters, as they tended to break up while . passing through the atmosphere. Of the three known groups of tektites, the most recent was that found widely across the Philippines, Indonesia, and Australia. These were perhaps 500,000 years old. Those found in Czechoslovakia were older, dating back to the Miocene age and in the region of 25m years old; the oldest were the Texan group, which were of Eocene age (about 50m years). Dr. Taylor could not offer any explanation as to why they were apparently confined to the latest stage of the earth’s several thousand million years of geological history: it could be, he said, that the glass of earlier tektites had devitrified, but there was no indication that this might be happening to any existing group.