Charles Darwin was given a specimen by Sir Thomas Mitchell in 1836
which he later described (1844) as a volcanic bomb made of obsidian.
Darwin's comments were the first scientific reference to these
curious glassy objects soon to be found scattered over a large
proportion of Australia. But similar objects had been found elsewhere
before, in Europe, where they had already proved difficult to
interpret. Ranging in shape; with forms including buttons,
dumb-bells, discs, spheres and colour; from black to yellow-green and
bottle-green such objects are very distinctive. Prof. Franz Suess in
1900 introduced the generic term tektite for all such materials and
specific terms such as australite for those from Australasia (the
European tektites are called moldavites). They were considered
distinct to meteorites in being distributed in particular fields and
always being of a very siliceous glassy nature. Mitchell's specimen
was collected from the sand plains between the Darling and Murray
Rivers, in the southeastern corner of the area now known as the
Australasian strewn field. Scientists like Charles Fenner and George
Baker would devote years to collection and examination in an attempt
to resolve the questions of tektite age and mode of origin.
Southwestern Victoria would prove an important place in the
development of our current understanding. The position of australites
at or near the surface and their shiny unweathered appearance
suggested a recent formation and deposition. Stratigraphic
interpretation of the deposits was that they were Late Pleistocene to
Holocene in age. When radiometric dating of tektites yielded ages of
770,000 years it created greater confusion. The radiocarbon work by
E.D. Gill seemed only to confirm the youthful age. The stratigraphic
question was clarified in 1999 with the publication of a paper
describing detailed work carried out in the Port Campbell Embayment
by E.M. Shoemaker and H.R. Uhlherr which showed australites derived
from a stratigraphic position in chronological agreement with the
radiometric determination. The origin of tektites was even more
controversial. In 1938 Fenner listed 15 separate theories as to their
mode of origin including relics from prehistoric glass factories and
lightning fusing sand in the air. While today the majority of
researchers would agree on formation due to the splashing of material
out of a meteoroidal impact on Earth (Terrestrial Impact Theory)
other theories such as the Extraterrestrial Volcanic Comet Theory
persist. Australites remain objects of interest and wonder.