one of the things Bruce does a nice job of, and I'd like to capture during this interview, is examining Bruce's theories versus accepted scientific theories re the same phenomenon. Maybe we could hash out a little geology / non vertebrate paleontology:
TEKTITES
“To anyone who has worked with them, tektites are probably the most frustrating stones ever found on earth.” – Henry Faul, 1966.
Faul’s description of tektites still holds true even today. While more data has been collected and theories on the origin of tektites have been reduced, these small, glassy objects still provide many questions for current tektite researchers. Let us begin our discussion with a brief history lesson.
What is a tektite?
Australite button
Tektites are rounded, pitted bodies of silicate glass, nonvolcanic in origin, most likely derived by large hypervelocity meteorite collisions with terrestrial rocks. Commonly about the size of a walnut, tektites can vary from sand grain sized microtektites, weighing grams, to large, blocky, Muong Nong-type specimens weighing up to 12.8 kg (28 pounds). Tektites can differ in both color and age, depending on where they are found. Commonly black color, tektites can also vary from light green to greenish yellow. Ages vary from ~35.5 million to ~750,000 years old. Chemically, tektites are uniquely characterized by extremely high silica contents ranging from ~70% in Australasian tektites to ~98% in Libyan Desert Glass. See
some examples from the NPL collections.
Current Thinking
Most current scientists theorize that tektites are formed by the rapid heating and subsequent cooling of quartz-rich soils and rocks. The impact of large meteorites with the surface of the Earth provides enough energy to melt soils and rocks and disperse the molten ejecta of these impacts great distances, forming tektites. Mixtures of shale and quartz sandstone or certain igneous rocks, possess similar compositions to that of the tektites, leading researchers to believe that these rocks may be the “parent” or “source” rock of tektites. Additionally, terrestrial soils, which cover almost the entire globe, have been found to also possess the proper chemical compositions, to create tektites. Produced by the erosion of many different source rocks, these soils would be a potential source of tektite-melt material. Before we begin discussing in depth the process of tektite formation, perhaps we should consider why the meteorite impact theory has gained favor with modern-day researchers.
Alternative Hypotheses
Obsidian
With tektites closely resembling obsidian, many early researchers believed that they were indeed products of terrestrial volcanic eruptions. Their various shapes were theorized to result from abrasion by wind-blown sand or shaping by water.
Chemical properties and the subsequent determination that tektite surfaces were ablated NOT abraded, later disproved this theory. At first glance, abrasion can look similar to ablation. Here’s how they differ: Abrasion is the mechanical wearing or grinding away of rock surfaces by the friction and impact of rock particles transported by wind, ice, waves, running water, or gravity. Ablation is the removal and reshaping of molten surface layers of meteorites and tektites by vaporization during flight through the Earth’s atmosphere. (definitions from Bates and Jackson (1984)).
Obsidian is found in nature as a black glass, a product of the ash trapped within the crystal, the presence of the green and yellowish-green moldavites and Libyan Glass, as seen below, provides an easy example of why this theory can be discounted.
Tektite (Muong Nong-type)
Many other theories were developed to try to explain the existence of tektites, some of these included:
The suggestion that tektites were actually man-made objects, created during the smelting process of ancient civilizations.
However, the chemical and physical property of tektites, as well as the stratigraphic ages of their localities completely discounts this theory. (Humans developed rudimentary smelting techniques as early as 6000 B.C., however, the youngest tektites are around 100,000 years old.)
The idea that natural fires such as forest fires or ground fires igniting coal seams could be a source of tektites.
Although these fires may reach very high temperatures, the presence of ablation shapes and other unique chemical properties in tektites discounted this theory.
Another proposed alternative for tektite formation was the fusing of silica-rich surface soil and dust by lightning.
These forms, called fulgurites, while having attained high enough temperatures to have melted the silica, do not have the same appearance as tektites, often occurring as soda-straw shaped tubes, as seen here, and possess none of the unique chemical and physical properties that set tektites apart from other naturally occurring glasses. In addition, the nature and scale of tektite occurrence discounts this theory as well. Lightning strikes occur thousands of times each day. If this theory held true, tektites would be found throughout the world, in great abundance.
Moldavite
Theories suggesting that tektites were material ejected from lunar volcanoes or that tektites were formed by the impact of meteorites with the Moon gained wide acceptance during the 1950’s and 60’s. However, some scientists doubted these theories, suggesting that tektites were actually formed on Earth by meteorite and/or comet impacts.
After the Apollo Moon landings scientists studied and compared the chemical composition of lunar rocks to tektites. Their conclusions showed that there was little to no similarity between tektites and lunar materials, shedding doubt on the lunar origin of tektites, and adding credit to the terrestrial impact theory that is now widely accepted.
==== now from Bruce's new book Exogenesis
- Tektite glass does not form every time our planet is impacted, in fact, there are only four identified tektite strewn fields despite the many cosmic impact events during geological history. These tektite strewn-fields in order of age are; North American (34 million years), Central European (14 million years), Ivory Coast (1 million years) and Australasian (0.78 million years).
- Australasian tektites (see button image at top of this post) are known as australites, and they really are in a division of their own. The first significant fact about australite is that despite being produced recently (in geological terms) and being exceptionally widely dispersed (associated microtektites reached over 10% of the Earth’s surface), there is no associated crater.
- Australite has an additional form which is not known among other tektites, the ‘flanged button’ which involved a unique double melting process...
One NASA report has this to say about the nature of the fragments:
“Experiment and analysis indicate that the button-type australites were derived from glassy spheres which entered or re-entered the atmosphere as cold solid bodies; in case of average-size specimens, the entry direction was nearly horizontal and the entry speed between 6.5 and 11.2 km/sec. Terrestrial origin of such spheres is impossible because of extremely high deceleration rates at low altitudes.”