SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES • NUMBER 17

Occurrence, Distribution, and Age

of Australian Tektites

R. 0. Chalmers, E. P. Henderson,

and Brian Mason

1376

SMITHSONIAN INSTITUTION PRESS

City of Washington

1976
ABSTRAC T

Chalmers, R. O., E. P. Henderson, and Brian Mason. Occurrence, Distribution,

and Age of Australian Tektites. Smithsonian Contributions to the Earth Sciences,

number 17, 46 pages, 17 figures, 10 tables, 1976.—Extensive field work has shown

that the Australian strewnfield is less extensive than previously thought, being

essentially restricted to the region south of latitudes 24° to 25°S. The few australites found north of this region probably represent specimens transported by

man. Throughout much of the desert interior australites are weathering out of a

late Pleistocene or early Recent horizon in a well-consolidated calcareous red

sandy aeolianite; field evidence indicates that in most places they are found essentially where they fell, or stream erosion and sheet wash has transported them

short distances and concentrated them in claypans and playas. Distribution within

the strewnfield is irregular and can be ascribed to: (1) original nonuniform fall;

(2) burial by recent deposition; (3) removal by erosion. Australites (excluding the

doubtful HNa/K type) show a continuous range of composition from 80% to

66% SiO2 with related variations in other major constituents, which is reflected

in the range of specific gravities (2.36-2.52) and refractive indices (1.493-1.529).

The composition range is not uniform over the strewnfield, the high-silica australites being concentrated along a northwest trending band extending from

western Victoria to the Lake Eyre region. Other noteworthy features are: (1) a

variation in the average size of australites from place to place, those on the

Nullarbor Plain being notably smaller (average <1 gram) than those of other

regions (average 3-5 grams); (2) the occurrence of many large australites (>100

grams) in the southwestern part of Western Australia.

Unsolved problems include: (1) the inconsistency between geological age (7000-

20,000 years BP) and K-Ar and fission track ages (700,000-860,000 years); (2) the

relationship, if any, between australites and the "microtektites" in Indian Ocean

sediments; and (3) the source region of the australite material.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded

in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: Aerial view of Ulawun

Volcano, New Britain.

Library of Congress Cataloging in Publication Data

Chalmers, Robert Oliver

Occurrence, distribution, and age of Australian tektites.

(Smithsonian contributions to the earth sciences ; No. 17)

Supt. of Docs, no.: SI 1.26:17

Bibliography: p.

1. Tektite—Australia. I. Henderson, Edward P., joint author. II. Mason, Brian Harold, 1917—

joint author. III. Title. IV. Series: Smithsonian Institution. Smithsonian contributions to

the earth sciences ; no. 17.

no. \1 [QE399] 550'.8s [523.5'1] 75-619432
Contents

Page

Introduction 1

Geographical Distribution and Relative Abundance 4

Mode of Occurrence 9

The Extent of the Australite Strewnfield 11

Australites in Relation to the Indoaustralian Strewnfield 15

Physical Properties and Chemical Composition 16

Form 16

Form Analysis 25

Weight 25

Specific Gravity 31

Refractive Index 32

Chemical Composition 36

Chemical Composition and the Origin of Tektites 38

Age and Stratigraphical Relationships 39

Literature Cited 44

u i
Occurrence, Distribution, and Age

of Australian Tektites

R. 0. Chalmers, E. P. Henderson,

and Brian Mason

Introduction

Australian tektites were first made known to science by Charles Darwin. In 1844, in his book

Geological Observations on the Volcanic Islands

Visited during the Voyage of H.M.S. Beagle, he described and illustrated a specimen (Figure 1) he

received from Sir Thomas Mitchell in Sydney in

January 1836. Mitchell had collected it "on a great

sandy plain between the rivers Darling and Murray," presumably during his exploration of the

Darling River valley in 1835. (The location ascribed to this australite by Baker (1973)—approximately 34°20'S, 143°10'E—appears to be erroneous,

since Mitchell did not travel south of 32°30'S, near

the present site of Menindee, on his 1835 journey.)

Darwin compared this australite to obsidian, but

noted that it was found "several hundred miles

from any volcanic region," suggesting that it might

have been transported either by aborigines or by

natural means. The suggestion that it might have

been a transported specimen was a prescient one;

very few australites have been found along the Darling, and the exceptional quality of Darwin's specimen would attract an aboriginal. Additional

records of the occurrence of tektites in Australia

are scattered through nineteenth- and twentiethcentury literature from 1855 to the present. This

information is summarized in the classic monographs of Suess (1900) and Baker (1959a).

Suess introduced the terms "tektites," denning

R. O. Chalmers, Australian Museum, Sydney, Australia. E. P.

Henderson and Brian Mason, Smithsonian Institution, Washington, D.C. 20560.

FIGURE 1.—Front, back, and side view of the australite given

to Charles Darwin by Sir Thomas Mitchell in 1836; specimen

is 26 X 22 X 7 mm (Institute of Geological Sciences, London).

them essentially as glassy meteorites, and "australites" as those tektites found in Australia. Tektites

occur in four general regions of the world. The

first and largest is the Indoaustralian region (Von

Koenigswald, 1960), encompassing, besides Australia, Hainan Island and the adjacent mainland of

China in the extreme southern section of Kwangtung Province, Vietnam, Cambodia, Laos, and

Thailand (indochinites), the Philippines (philippinites), Malaysia (malaysianites), and Indonesia.

Barnes (1963) introduced the term "indomalaysianites" to refer to tektites from Malaya, Java, Borneo,
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

and the adjacent small islands of Billiton and

Bunguran, and those few other Indonesian islands

on which an occasional specimen is found. Outside

the Indoaustralian region two more geographically

defined groups are moldavites (vltavines) from the

Moldau (Vltava) River valley and areas further to

the east in Czechoslovakia, and bediasites from

Texas. Finally, tektites are found on the Ivory

Coast, West Africa. Materials sometimes classed as

tektites, but distinct from them in appearance and

composition, are silica glass from the Libyan Desert

and Darwin Glass from Mt. Darwin in Tasmania.

The australites occupy a unique position among

the tektites. Their strewnfield is by far the most

extensive of any of the above-named groups. They

show a wider range of composition (e.g., 66%-80%

SiO2) than most tektite groups. Whereas practically

all other tektites have been found in alluvial deposits and have lost their original surface by abrasion or solution, many australites have been

recovered with their original surface well preserved,

showing delicate markings produced by aerodynamic ablation. This enables significant deductions

to be made regarding their original form and its

modification during passage through the Earth's

atmosphere.

Interest in tektites as a group, and australites in

particular, has waxed and waned from time to time.

Comparatively little research on australites was

reported in the first thirty years of this century.

Then Dr. Charles Fenner, in a series of papers published between 1933 and 1955, provided a large

amount of new information on numbers, forms,

and distribution. Commencing in 1937, Dr. George

Baker wrote a large number of papers on australites, especially those from localities in Victoria

and South Australia. In 1959 his comprehensive

monograph "Tektites" was published, with a very

full bibliography, although one early reference not

listed is Clarke (1869) He continued to expand

and interpret the data available on these enigmatic

objects until his death in 1975.

International interest in tektites greatly increased

after World War II as part of a general increase in

interest in meteorites. Suess originally had postulated an extraterrestrial origin for tektites. The discovery that tektites show no evidence of cosmic-ray

bombardment in outer space (Anders, 1960, and

Viste and Anders, 1962) indicates a relatively brief

flight while outside the Earth's atmosphere, and

thus supported the suggestion by Nininger (1943)

that a meteorite impact on the moon was the

mechanism that sent tektites to Earth. When plans

were being made for manned moon landings, scientists at the National Aeronautics and Space Administration began an intensive study of all things

connected with the moon, including tektites. Chapman and Larson (1963) further adduced a great

deal of aerodynamic evidence to substantiate the

theory of lunar origin. On the other hand, the work

of Taylor (1962, 1966) and Taylor and Kaye (1969)

showed that the composition of tektites was comparable to that of sedimentary rocks of the subgreywacke type. Bouska (1968) considered that all

tektites from the entire Indoaustralian region

might have been derived from impact on igneous

rocks, but that tektites from other regions were

derived from sedimentary rocks. These findings

suggested a possible origin by meteoritic impact on

Earth and not on the moon. This possibility was

strengthened by the discovery that moldavites had

the same K-Ar age as the Ries crater in southern

Germany and that the Ivory Coast tektites were the

same age as the glass in the Bosumtwi crater in

Ghana (Cohen, 1963, Gentner et al., 1963, Faul,

1966). As a result, the extraterrestrial origin once

widely accepted was seriously challenged, and an

origin due to large-scale impact on Earth gained

favor.

Because of this increased interest, the demand for

research material has steadily expanded, and the requirements therefor have become more rigorous,

in terms of exact locality, mode of occurrence, and

quality of preservation. On this account, we organized in 1963 an expedition designed to provide

more and better documented material for our respective institutions: the Australian Museum (Chalmers), the Smithsonian Institution (Henderson, and

Mason since 1964), and the American Museum of

Natural History (Mason, 1963 and 1964). The success of the 1963 expedition, and the questions it

raised about the geological occurrence, distribution,

and age of australites led to further lengthy journeys in 1964, 1965, 1966, 1967, and 1969 (Figure 2),

which covered most of the strewnfield on the continent. (Australites have also been found on Tasmania, but we have not investigated these occurrences).

Special efforts were made to investigate the more

remote regions in the arid interior, and to follow

up any promising leads. In addition, much time
NUMBER 17

.Brisbane

FIGURE 2.—Routes of field expeditions, 1963-1967.

was devoted to defining the northern margin of the

strewnfield, an arduous and, in terms of specimens,

a rather unproductive exercise.

Besides the support of our respective institutions,

we are greatly indebted to the National Geographic

Society for a grant financing the initial expedition

and continuing support for the later journeys. A

grant from the National Science Foundation supported Henderson in 1963, and one from the

Smithsonian Research Foundation aided Mason in

1967. In addition, the award of a fellowship by the

John Simon Guggenheim Foundation enabled Mason to spend several months at the Australian National University in Canberra in 1969 on laboratory

investigations and fruitful discussions with Australian colleagues. During our travels we have been

given great assistance and enjoyed generous hospitality through the sparsely populated interior of

Australia. It is not feasible to name everyone who

helped us in our work, but special mention is due
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

to the following: Mr. Frank Nicholls of Pindera,

N. S. W.; in one of our prime collecting regions

near Lake Torrens, Dr. and Mrs. G. C. Gregory,

Mr. Noel Smith, Mr. J. Moroney and Mr. R.

Craigie; in another prime collecting area in the region of the eastern edge of Lake Eyre and the Birdsville Track, the late Mr. G. Patterson of Farina,

Mr. K. Price of Muloorina, Mr. Kevin Oldfield of

Clayton, Mr. Brian Oldfield of Etadunna, and Mr.

G. Bell of Dulkaninna. Actual assistance in collecting was given by Mr. H. S. St. J. Disney, Mr. H. O.

Fletcher, Mr. R. Lossin, Mr. D. Hamlyn, Mr. P.

Robinson, Dr. and Mrs. L. E. Weiss, the late Mr. A.

A. Walker, and Mr. D. F. Walker. On one field

trip Mr. D. F. Walker provided a second vehicle. In

other areas the cooperation of the following is acknowledged: Mr. J. E. Johnson of Adelaide, Mr. P.

D. Boerner of Alice Springs, Mr. Barton Jones, Mr.

W. H. Cleverly, and Mr. K. Quartermaine of Kalgoorlie, and Mr. and Mrs. C. Smith of Earaheedy

Station, northeast of Wiluna. We are indebted to

curators of major australite collections for much

useful information, especially Dr. A. W. Beasley of

the National Museum of Victoria, Dr. D. W. P. Corbett and Miss J. M. Scrymgour of the South Australian Museum, Dr. D. Merrilees of the Western

Australian Museum, and Mr. D. H. McColl of the

Bureau of Mineral Resources, Canberra. We also

thank Dr. Dean Chapman for many illuminating

discussions and for the use of some of his unpublished information.

Geographical Distribution and Relative

Abundance

In Table 1 a large number of australite collections are listed giving the numbers, weights, and

geographic coordinates of each collection. The majority of these collections were made by us, and, for

these, exact localities and mode of occurrence are

recorded in our field notes. Some of the collections

listed were presented or loaned by individuals.

Others were purchased. The repositories for all

these collections are shown. The numbers in Table

1 are only a rough indication of the relative abundance of australites at the different localities. Some

localities, for example Pine Dam in the Lake Torrens region, have been collected intensively and repeatedly. Other localities represented one or two

man-hours of rapid reconnaissance. Nevertheless,

within the range of our journeys, the relative

abundance, as illustrated in Figure 3, has some basic

significance. It is apparent to us that australites did

not fall uniformly over the whole strewnfield. In

certain regions, for example that on the northeast

margin of Lake Torrens, australites are notably

abundant; other regions, situated no great distance

away and similar in geology, topography, and climate are much less productive or apparently quite

barren. Thus, on the western edge of Lake Torrens,

on Arcoona Station, near Woomera, only about 60

australites have been found in some 40 years of

collecting by Michael Mudie. Another example of a

relatively unproductive area is on Pindera in the

far northwestern corner of New South Wales. Here,

over a period of about 50 years, 155 specimens were

collected first by V. C. W. Nicholls and later by his

son Frank. Admittedly in these two instances the

australites have been found by graziers engaged in

their day-to-day duties and not specially searching

for them. Even within a productive region the

abundance varies greatly within comparatively

short distances.

Of course, the productivity of an area depends

not only upon the original density of fall of the

australites, but also on subsequent events, in particular (1) erosion, (2) deposition, (3) distribution

by animals or man, and (4) prior collecting.

Erosion may operate either to concentrate or to

disperse australites, depending upon local conditions. On the Nullarbor Plain, which covers a large

area straddling the South Australia-Western Australia border, australites appear to be randomly

and rather sparsely distributed over most of its

extent. However, small shallow circular depressions (known locally as "dongas") frequently provided somewhat more productive collecting, the

australites presumably being concentrated by sheet

wash accompanying the rare heavy rains. Over

much of the arid interior, wind erosion (deflation)

is the principal agency for exposing australites. On

the other hand, in regions of moderate to strong

relief, stream erosion is likely to bury the rare

australites in the mass of alluvium, and rapidly destroy all but the large specimens. Deposition of

recent alluvium and especially wind-blown sand

makes many large areas unrewarding to collect.

None were found in interdune areas where the

floors were silted up by the action of rivers such as

Cooper Creek, Strzelecki Creek, and Diamantina
NUMBER 17

TABLE 1.—Number, weight, and current location of australites acquired by Australian Meteorite

Expeditions, 1963-1967, ordered approximately from east to west (AM = Australian Museum,

AMNH = American Museum of Natural History, SI = Smithsonian Institution)

Locality

Pindera

(1963)

Pindera

(1966-7)

Pindera

Currawilla

Mooraberree

Durrie

Durrie

Cuddapan

Mutooroo

Oakvale

Frome Downs

Wilpena Creek

Yunta

Waukaringa

Mannahill

Motpena

(1964)

Motpena

(1967)

Motpena

Beltana

(1966)

Beltana

(1967)

Pine Dam

(1963)

Pine Dam

(1964)

Latitude/

Longitude

29°27'

142°29'

tt

II

25°09'

141°20'

25°16'

140°58'

25°53'

140°06'

25°48'

32°29'

140°50r

32°59'

140°47'

139°55'

31°04'

139°42'

32°27'

139°32'

32°14'

139°27'

32°25'

139°59'

138°15'

"

30°54'

138°12'

"

30°25'

138°02'

Number

3

3

6

36

3

2

1205

99

82

1

31

7

15

1

1

97

3

33

76

236

212

49

97

97

340

Total wt. (g)

12

15

13

154

6

13

2315

98

143

16

149

19

34

2

5

126

11

59

198

585

666

139

262

260

553

Where preserved

SI

AMNH

AM

AM

AMNH

AMNH

AM

SI

SI

AM

SI

SI

AM

AM

AM

SI

AM

SI

SI

AM

SI

SI

AMNH

AM

SI

Notes

gift F. Nicholls

gift V.C.W. Nicholls

gift G. Hume

bought from G. Hume

bought from G. Hume

gift W. Crack

gift N. Bartlett

gift R. Craigie
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 1.—Continued

Locality

Pine Dam

(1965)

Pine Dam

(1967)

Mt. Victory Well

(1964)

Mt. Victory Well

(1966)

Mt. Victory Well

(1967)

Busheowie

Mulgaria

(1964)

Mulgaria

(1965)

Mulgaria

(1967)

Andamooka

Island

Finniss

Springs

Lake Arthur

Lake Eyre

South

Clayton River

Dulkaninna

(1964)

Dulkaninna

(1967)

East Peachawarinna (1964)

East Peachawarinna (1967)

East Peachawarinna (1967)

West

Peachawarinna

East

Tankamarinna

Latitude/

Longitude

30°25'

138°02f

"

30°25'

137°51'

ii

30°13'

137°53'

30°14'

137°38'

II

30°53'

137°40'

29°33'

137°16'

29°32'

138°46'

29°14'

137°43'

29°15'

138°08'

29°06'

138°20'

"

29°03'

138°19'

II

M

29°03'

138°17'

28°57'

138°27'

Number

19

76

4

202

6

18

218

95

12

1

5

9

14

6

54

59

72

47

8

7

5

Total wt. (g)

47

81

16

300

4

136

361

121

15

8

62

13

94

22

99

62

179

55

16

33

48

Where preserved

AM

SI

AM

AM

SI

AM

AM

SI

SI

AM

AMNH

AM

AMNH

AMNH

AMNH

AM

AMNH

SI

AM

AM

AMNH

Notes

gift G.C. Gregory

gift B. Murray

gift D. Hamlyn

gift G.C. Gregory
NUMBER 17

TABLE 1.—Continued

Locality

West

Tankamarinna

Mulka

N.W. of Mulka

Mungeranie

New Kalamurina

(1964)

New Kalamurina

(1967)

Alton Downs

Simpson

Desert

Charlotte Waters

Macumba

Ooldea

Near Watson

SE of Cook

N of Cook

Denman

S of Hughes

N of Hughes

(1965)

N of Hughes

(1967)

NE of Deakin

N of Deakin

Eucla

Latitude/

Longitude

28°58'

138°18'

28°18'

138°48f

28°12'

138°24'

28°10'

138°30'

27°44'

138°15'

"

26°08'

138°58'

26°24'

137°27'

25°55T

134°55'

27°15'

135°42'

30°38'

132°03'

30°31'

131°20'

30°58'

130°42'

30°10'

130°25'

30°40'

129°58'

30°55'

129°42'

30°30'

129°30'

ti

30°30'

129°05'

30°32'

128°59'

31°43'

128°55'

Number

299

11

15

38

1

1

1

13

38

19

58

21

24

14

170

66

28

894

452

91

50

93

2

Total wt. (g)

492

20

40

88

0.5

1

1.3

36

162

70

47

18

7

25

92

46

23

452

254

69

26

49

11

Where preserved

AM

AMNH

SI

SI

AMNH

AM

AMNH

AM

SI

SI

SI

SI

SI

SI

SI

AM

AM

SI

AM

SI

AM

AM

SI

Notes

gift J. Findley

coll. J. Dunn;

gift G.C. Gregory

gift R. Syme

bought from railwayman
SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 1.—Continued

Locality

N of Forrest

Mundrabilla

Loongana

N of Loongana

Lake Yindarlgooda

Lake Wilson

Mt. Davies

SE of Earaheedy

S of Earaheedy

Granite Peak

Millrose

Latitude/

Longitude

30°20'

128°05'

30°56'

127°31'

30°57'

127°02'

30°15'

127°02'

30°42'

121°54'

26°01'

129°36'

26°llf

129°07'

25°50'

121°58'

25°40'

121°34'

25°38'

121°20'

26°24'

120°57'

Number

4

14

2

8

79

72

28

21

112

36

100

1

Total wt. (g)

5

13

0.5

4

360

274

51

152

210

53

467

28

Where preserved Notes

AM

AM

AM

AM

SI

AMNH

SI

SI bought from natives

SI

SI

SI gift E. Juniper

SI

(Warburton) River. Many parts of the arid interior

are sandplains with the sand fairly well fixed by

the desert vegetation. Aeolian deposition, rather

than erosion, is dominant in the regions of these

sandplains. Australites may, however, be picked up

in local blow-outs or found in the debris around the

holes made by such animals as wombats and rabbits.

Prior collecting strongly affects the return from

any locality. Johnson (1964) records collecting 1451

australites in 15 man-hours from the floor of Lake

Wilson, a playa about IV2 x 1 mile in extent in the

far northwest of South Australia; our visit in 1965

produced 28 australites in 18 man-hours. Johnson's

party evidently harvested a crop which had accumulated probably over a period of hundreds or

perhaps thousands of years; our collection represents a gleaning of the few they had overlooked.

Our experience with some of the claypans in the

Pine Dam area which have been re-collected at a

later date suggests that a systematic search over a

limited area will net a major fraction of the australites present (perhaps 75%-95%), and few will

be recovered on later visits to the same area. This

indicates that, even in localities where australites

are relatively abundant, the slow rate of natural

erosion (mainly deflation in the arid interior) results in a very slow release of australites from the

matrix in which they are buried. Of course, in

humid regions such as the Port Campbell area of

Victoria, where Baker and others have collected

successfully over many years, the abundant rainfall and accelerated erosion caused by roadmaking

and other human activities have provided a continually prolific source of australites.

It may be of interest to sum up our experiences
NUMBER 17

QUEEN SLAND

AUSTRALITE LOCALITIES COLLECTED

NumbersLocality not1 —10

10-100

>IOO

collected

o

X

V

2.41

V2.45

'** o • .•

O Xril ' Broken Hill NEW SOUTH

WALES

FIGURE 3.—Australite localities collected during the Australian Meteorite Expeditions, 1963-1967;

the symbols indicate the numbers of individual specimens examined, and are not indicative of

the total number of specimens found at any locality. The figures give the peak specific gravities

for the larger collections, along with some data from published papers (Table 7).

in regard to productivity. We have found that, in

areas where australites are relatively abundant and

have not been intensively collected, a return of 3-4

per man-hour is about normal, although even

within such areas the recovery rate will vary quite

widely. A record collection of 81 in one man-hour

was made in 1965 in a shallow depression in the

Nullarbor Plain north of Hughes; a return visit to

the same locality in 1967 netted 9 in one man-hour.

MODE OF OCCURRENCE

Over much of the area in which we have collected (excluding for the moment the Nullarbor

Plain), the topographic, geologic, and climatic

conditions are extremely similar throughout.

Most of the country is extremely flat, an integrated drainage pattern is practically absent (except

close to large intermittent rivers such as the Frome

and the Cooper), and the topography is longitudinal sand dunes (seif dunes), usually 30-60 feet

high, separated by interdune corridors occupied by

claypans at their lowest spots. Wind erosion is

dominant, and the runoff from rare heavy rains

produces only local erosion and deposition around

the individual claypans. The claypan surfaces are

the natural collecting grounds for australites.

The geological setting is remarkably uniform

over vast areas, and is illustrated in Figure 4 by

sections through dunes and claypans at Motpena

and Myrtle Springs (Pine Dam) in the Lake Torrens region of South Australia. There are essentially three formations represented:

1. Unconsolidated sand forming the crests of

the dunes and veneering large areas of the interdune corridors.
10 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

concentration of australitcs

modern sand

MOTPENA

H227900t500|

ANU-127

concentration of australites

I

MYRTLE SPRINGS

i20.310t360|

ANU-127

MID-HOLOCENE SANDS MIHII'I MflTPFNA PAIFQ<5Ol

Alluvial at Motpena. aeolian at |W§il|)

 M0TPEN A

 PALEOSOL

Myrtle Springs.

LAKE TORRENS FORMATION

POORAKA FORMATION

t equiv. aeolian sand at

Myrtle Springs.

|ll{(| | WILKATANA PALEOSOL

600Q+100 C14 DATE. CHARCOAL

|i2,050t160 ] CK DATE. CARBONATE

FIGURE 4.—Schematic sections through the late Quaternary

sediments and paleosols at Motpena and Pine Dam, Myrtle

Springs, showing the areas within interdune corridors where

australites are commonly found (Lovering et al., 1972).

2. A well-consolidated calcareous red sandy formation, almost- certainly an aeolianite, which is

widespread in every area we visited.

3. A calcareous red-brown formation containing

abundant carbonate nodules that forms the floor

of the claypans in the interdune corridors.

These three formations in the Pine Dam area

have also been noted by Corbett (1967).

Williams and Polach (1971) have suggested a late

Quaternary chronology for the events that have

occurred over the last 38,000 years in the Lake

Torrens plain, including the deposition or accumulation of the above three formations. They

have named formation 2 the Lake Torrens Formation (deposited ca. 20,000-16,000 BP) capped by

the Motpena paleosol (formed ca. 16,000-12,000

years BP); formation 3 has been named the

Pooraka Formation (deposited 30,000 BP and

earlier) capped by the Wilkatana paleosol (formed

on the Pooraka Formation prior to the deposition

of the Lake Torrens Formation). The Wilkatana

paleosol is covered by mid-Holocene sands in many

of the interdune corridors.

Williams and Polach (1971) noted that in the

Lake Torrens plain, as in all arid and semi-arid

regions of the world, accumulations of carbonate

nodules form well-developed horizons in soils and

paleosols of both alluvial and aeolian origin. They

determined the ages cited above by carbon 14 dating

of carbonate nodules from these horizons. Carbonate nodules are invariably thickly scattered on

the surfaces of both the Motpena and Wilkatana

paleosols.

At Pine Dam a total thickness of about 12 feet

of the Motpena paleosol is exposed. Within this

thickness two layers of carbonate nodules occur,

one about two feet from the top and the second

some six feet lower. The carbonate nodules in the

upper layer are small (fingertip size and smaller);

those in the lower layer are larger (up to fist size)

and much less friable.

Our experience indicates that in the Pirte Dam

area the australites occurred originally in a horizon

at or near the top of the Motpena paleosol. One

australite has been found partly embedded in the

Motpena paleosol at Motpena (Lovering et al.,

1972) and another in the Motpena paleosol near

Pine Dam by R. O. Chalmers in 1969. Several have

been found partly embedded in mid-Holocene alluvial and aeolian deposits at Motpena (Lovering

et al., 1972) and the Pine Dam area (Corbett,

1967).

Some 8 miles southwest of Beltana railway station and about 10 miles north of the Motpena

locality there is an isolated area measuring about

5 by 4 miles of Lake Torrens Formation lying on

a surface of rocks of Proterozoic age. The area is

low and eroded, revealing areas of Motpena paleosol, dated by Lovering et al. (1972) at 12,540 years

BP (their Nilpena locality). Dunes of unconsolidated sand lie on this paleosol (Figure 5). Interdune corridors run between the low dunes, but

erosion has not proceeded far enough to produce

the bare claypan floors characteristic of the Pine

Dam area. Australites occur both on the eroded

paleosol and in the shallow interdune corridors; a

group of them, of larger than average size, is shown

in Figure 6.

In deeply deflated interdune corridors, as in the

Pine Dam area, the claypan floors consist of the

Wilkatana paleosol and many australites are found

lying on this surface. Sheet wash during heavy rain

has no doubt moved them from the margins of

the claypan where they have been shed from the

Motpena paleosol.
NUMBER 17 11

' 1 - . "MTB/P-I •":••• • ••**, • i.''- 1' • • •••^ T - *

FIGURE 5.—Erosion remnants of Motpena paleosol partly covered by unconsolidated sand, southwest of Beltana Station, South Australia; australites were found on the bare surface in the foreground.

Australites are not found everywhere the

Motpena paleosol is exposed in the Lake Torrens region, nor where formations resembling the

Motpena paleosol outside the Lake Torrens region

are exposed. The principal reason for their absence in what might be regarded as a favorable

environment is that they presumably fell within a

very short time interval while this formation was

being deposited, and thus mark a thin stratigraphic horizon. If the australite horizon is not

yet exposed, no australites will be found. If the

australite horizon has been eroded away, australites may survive, but will be subjected to rather

rapid destruction by sandblasting and transportation. Hence recovery of well-preserved australites

near outcrops of this formation is prima facie evidence for the presence of the australite horizon

therein.

Of course it is unlikely that the australite

strewnfield coincides with the geographical extent

of these formations resembling the Motpena paleosol, so the absence of australites at any locality is

no evidence that the time interval of australite arrival is not represented therein. For example, we

noted typical exposures in western Queensland between Birdsville and Bedourie but our search there

failed to find any australites. However, subsequent

to our field work in this area Gordon Hume has

found between 1000 and 1500 on a large claypan

46 miles east of Birdsville (25°53', 140°06'), and a

considerable number at nearby Cuddapan (25°48',

141°15)

THE EXTENT OF THE AUSTRALITE STREWNFIELD

Figure 3 shows localities where we collected between 1963 and 1967. Localities collected by other

investigators, notably Fenner (1940), Chapman
12 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

r

FIGURE 6.—A group of larger than average australites collected from the area of Figure 5; the

central specimen is 54 mm long.

et al. (1964), and Baker (1956, 1959a, 1969b), are

shown by dots. Distinctive symbols indicating the

numbers we collected at each locality are shown.

As will be discussed later, peak values for specific

gravities are also shown. It is impossible to show

complete data for all localities on a single map

of Australia. The reader is referred to the following publications containing maps showing australite localities and/or data on numbers recorded:

Baker (1956, 1959a, 1959b, 1961a, 1964a), Barnes

(1963), Chapman (1964, 1971), McColl and Williams (1970), and Cleverly (1973, 1974). Although

not shown on Figure 3, australites have been

found on islands in Bass Strait, and in Tasmania,

mainly in the northeast in cassiterite-bearing alluvial deposits.

To some extent, of course, the distribution indicated in Figure 3 and in maps in the above-mentioned publications is an imperfect representation

of the strewnfield as a whole. To be established, a locality has to be visited by someone

sufficiently observant to recognize australites. How-
NUMBER 17 13

ever, comparatively little of Australia has not yet

been subjected to fairly careful reconnaissance,

either by pastoralists, station hands, surveyors, or

prospectors, most of whom are excellent observers

and unlikely to pass over exotic material like australites. Moreover, we know of instances where

pastoralists, having no prior knowledge of australites, were stimulated by the interest we aroused to

search intensively and with considerable success in

the course of their work on their stations. Most

areas where 1000 or more australites have been collected are in arid or semi-arid regions where it is

easier to find them than in well-vegetated areas of

higher rainfall. Also a locality cannot be established

unless the finders pass on the information to persons

interested in recording it. Density of population

and pastoral or mining activities are other factors

that favor the finding of australites. The large

number of productive areas around Kalgoorlie and

adjacent sites in Western Australia can certainly

be ascribed to intensive prospecting for gold as

well as to the relative aridity of this region. On

the other hand, Broken Hill in western New South

Wales has about the same population as Kalgoorlie, the same semi-arid climate, and the surrounding districts have been prospected equally as

thoroughly, but relatively small numbers of australites have been found, which again reinforces our

belief that the australites did not fall uniformly

over the whole strewnfield. Factors that partly explain the concentration of localities in Victoria are

that it is the most densely populated state in

Australia and that there has been extensive agriculture and mining. McColl and Williams (1970)

state that, out of the dozens of australite localities

in Victoria, there is only one where more than

1000 have been collected, two where between 100

and 1000 have been collected, and three where between 10 and 100 have been collected. These lie

on a southeast-northwest line extending from Victoria through South Australia to the Charlotte

Waters region on the South Australian-Northern

Territory border. The concentrations are distributed unevenly, and they regard this as being

due in the main to the irregular nature of the

fall. One major fact supporting this hypothesis is

the absence of australites in Eyre Peninsula in

South Australia or in its extension to the northwest, to beyond the Trans-Australian Railway.

This area is bounded to the west by the Nullarbor

Plain and to the east by Spencer's Gulf. Much

of the Eyre Peninsula is blanketed by recent sand,

but along the railway from Port Augusta to beyond Tarcoola, a distance of some 300 miles, the

relief and erosion would surely have been sufficient

to have exposed an australite horizon. We regard

this apparent absence as significant.

The farthest north we have collected australites

is on Currawilla Station in southwestern Queensland (25°09', 141°20/

). At Mooraberree Station,

about 30 miles further west, some 40 have been

collected over 30 years, which is an indication of

how sparsely they are distributed in this region.

About 70 miles to the southwest, as already mentioned, abundant australites have been collected

on claypans in the vicinity of Durrie station by Mr.

Gordon Hume. Further west along the BirdsvilleBedourie road conditions are favorable for finding

australites, but we had no success and local people

had found none. In our travels along the Birdsville

Track from Marree to Birdsville, collecting was

good until north of Cooper Creek. We were successful in only three localities between here and

Birdsville, viz., in an area of big sandhills east of

Ooroowilanie towards the Cooper, at Alton Downs

at latitude 26°06' on the eastern border of the

Simpson Desert where only one was found, and at

Kalamurina, latitude 27°50', where only two were

found. A few miles north of where the Cooper

crosses the Birdsville Track many hundreds have

been found near Mulka (Tables 1 and 7). A

collection from Mungeranie is also listed in Table 1.

We have not investigated the region of the Simpson Desert, one of the largest uninhabited regions

remaining in Australia (latitude 23°30' to 27°30'

and longitude 132°50' to 139°00'). But Mr. R. C.

Sprigg, who has traveled extensively there, informs us that while australites are common

throughout the southern part they become progressively less abundant the further north one goes,

until north of latitude 25° few if any are found.

This statement is supported by the absence of any

reference to australites in Madigan's (1946) account of the 1939 Simpson Desert Expedition.

Madigan would have been familiar with australites because Fenner (1935) records a collection in

his possession. The main desert area crossed by the

expedition from east to west lay between latitudes

24° and 25°. From latitude 25° to Birdsville in

latitude 25°54' the route went southeast. In about
14 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

1967 Mr. Robin Syme, a member of a geophysical

exploration team working in the Simpson Desert,

made a small collection which he presented to the

Australian Museum. He stated that larger collections were made by other members of the exploration team. The locality was about 125 miles

south-southwest of Birdsville at latitude 26°23' and

longitude 137°27'. The nearest named locality is

Peelicanna Native Well.

The Charlotte Waters strewnfield covers quite a

large area extending from Finke to about 50 miles

south into South Australia, and 70 miles east into

the western fringes of the Simpson Desert. About

seven or eight thousand have been collected here

(Fenner, 1940). Beyond Finke in the Northern Territory they are rare or absent. Specimens in the

South Australian Museum are stated to have come

from Henbury (latitude 24°35'), and specimens in

the Australian Museum collection from 5 miles

north of Alice Springs (latitude 23°37'), but nothing is known in either case of the circumstances

in which they were found. Fenner (1935) quotes

Charles Chewings, a geologist with intimate knowledge of the Northern Territory, as having neither

heard of nor seen a single specimen north of the

MacDonnell Ranges. Our experience confirms this,

and enquiries of .the aboriginals from Alice Springs

northwest to the Western Australian border and

beyond to Halls Creek were also negative. Jensen

(1915) states: "Mr. William Laurie informs me

that obsidian buttons are common about Bullock's

Head about 40 miles from Tanami on the Granite

Road." The latitude of this place is 20°25', which

is well north of the apparent northern border of

the australite strewnfield. However, the original report is hearsay unsupported by specimens and no

confirmation has been forthcoming in the 60 years

since the report was made (Cleverly, pers. comm.).

Australites are abundant near the South Australian-Northern Territory corner (26°00', 129°

00'), where many thousands have been collected

by the aboriginals and traded through the Department of Aboriginal Affairs in South Australia. In

Western Australia, just over the border west of this

corner, Baker (1961a) records australites at Wingellina. We found a few near the Cavenagh Range,

60 miles to the west of Wingellina. We found

none on a traverse 100 miles north from Mt.

Davies towards the Rawlinson Range. Mr. R. C.

Sprigg informs us that none were found during

his travels in the region of the Northern Territory-Western Australia border. Our northernmost collecting locality in Western Australia was

Earaheedy Station (25°40'5 121 °00'). North of here

the country is uninhabited for several hundred

miles although most of it has been traversed during geological explorations. Mr. D. McColl of the

Bureau of Mineral Resources, Canberra, has informed us that he has reports of australites north

and east of Earaheedy at 24°32', 125°03' and 22°

15', 125° 13'. If the latter is correct the known

strewnfield would be extended considerably to the

north. Unfortunately we have been unable to confirm this. Talbot (1910), who made an extensive

geological survey along the Canning Stock Route

from Wiluna to Halls Creek, records "obsidianites" near No. 14 Well and notes, "I did not see

one anywhere else, although a careful look out was

kept for them. One would not expect to find them

among the sand ridges as they would be covered

by drifting sand, but there were several areas along

the stock route whose conditions were just as favorable for their preservation and exposure as in this

locality." Apart from this record (which may, however, have been transported specimens) there are

few australite localities north of the 25th parallel

of latitude.

Distribution by man probably explains the occasional discovery of one or a few australites in

regions north of the apparent border of the strewnfield. They have been reported from Wodgina

(21°11/, 118°40'), but this is an old mining district

and prospectors would have come from many parts

of Australia and could have brought them with

them. The presence of australites in gold-bearing

gravels in New South Wales and Victoria gave rise

to the idea of australites as being talismans in the

search for gold, and many prospectors valued them

as such. There are specimens in the Australian

Museum collection from Halls Creek, but since

this is the northern terminus of the Canning Stock

Route they may have been picked up by drovers

traveling the route and discarded in Halls Creek.

Transport by man is also indicated by the recovery

of australites in mining camps in New Zealand and

California. These were undoubtedly carried by

prospectors from Australia. Also, australites are

attractive as crop stones for large birds such as the

emu (Dromaius novae-hollandiae) and the bustard

or plain turkey (Eupodotis australis). Fenner
NUMBER 17 15

(1949) records a plain turkey shot in South Australia which had 49 australites and two other black

stones in its crop. But large birds range much less

widely than man so probably do not distribute

australites over long distances.

There are a number of references to the utilization by aboriginals of australites as agents of healing and magic and ceremonial objects, and also

records of complete and broken specimens (some

of which are definitely artefacts) in aboriginal

campsites. It is therefore certain that aboriginals

have transported australites. Baker (1957), Johnson (1963, 1964) and Edwards (1966) deal with

the significance with which aborigines regard

australites, and record occurrences in campsites in

Victoria, South Australia, and in Western Australia adjacent to the Northern Territory-South

Australian border. Edwards comments: "The Australian aboriginal used australites in mythology

and for the manufacture of implements. The latter

use appears to be of minor importance and mainly

confined to areas where suitable stone materials

are in short supply." Our own experience confirms

this; we found aborigine-worked australites common only on the Nullarbor Plain and on Earaheedy Station, areas where the silicified rocks

preferred for implements are totally lacking. In

the far north of Western Australia, C. E. Dortch

(Cleverly and Dortch, 1975) found six australite

specimens in prehistoric rock-shelter occupation

sites within the area now largely inundated by

Lake Argyle in the Ord Valley. Five of these were

flaked artefacts. The authors concluded that this

occurrence probably resulted from long-range

trade, dating to the late Pleistocene, between the

prehistoric inhabitants of the Ord Valley and more

southern regions where australites occur naturally.

Some years ago the owner of Marion Downs, a

station 35 miles south of Bouila in northwest

Queensland (23°20', 139°40'), reported that an

aboriginal there had a large round australite core,

chipped at the edges; he stated that he had carried

it for long distances over many years and obviously

treasured it. Another example of aboriginal interest in australites is afforded by the discovery of a

77.5-gram oval at Pindera, in the far northwest of

New South Wales. The finder, Frank Nicholls, an

experienced anthropological observer and collector

of australites, stated that it was in an old aboriginal campsite on the edge of a gibber plain.

We devoted considerable time and effort to establishing a northern boundary for the strewnfield.

Naturally this is a difficult task, and absolute certainty in delineating such a boundary is not to be

expected. The difficulties can be seen from our discussion on the mode of occurrence of australites.

Nevertheless, the map shows a remarkable dearth

of localities north of latitude 25°. We have

checked as many of these localities as possible and

have made careful enquiries regarding australites

throughout our journey in this region. If the local

people, especially aboriginals, have never seen

australites in their regions, it is a reasonable conclusion that they have not fallen there. On the

basis of all the evidence we have been able to

gather, an east-west zone along 24°-25° latitude

appears to mark the northern limit of the australite strewnfield.

AUSTRALITES IN RELATION TO

THE INDOAUSTRALIAN STREWNFIELD

The australites are usually grouped with the

tektites found in southeast Asia, the Philippines,

and Indonesia in a single strewnfield, the Indoaustralian (von Koenigswald, 1960) or Australasian

(Chapman, 1964) strewnfield (Figure 7). This grouping is based not only on geography, but also on

(1) chemical similarity—the range of australite

compositions is duplicated by analyses of tektites

from other parts of the strewnfield; and (2) similar

potassium-argon ages—tektites from throughout

the strewnfield give approximately the same age of

750,000-950,000 years, within margin of error.

However, there are significant differences between tektites within this vast region. The characteristic aerodynamically shaped, flanged forms of

the australites are unknown in other parts of the

strewnfield, except perhaps in a few specimens

from central Java. Australites are much smaller

than tektites from the Philippines and Indochina.

They usually weigh less than 10 grams (the largest

australite ever found was 437.5 grams) whereas

tektites from the Philippines and Indochina may

weigh more than 1 kilogram. On the basis of morphological differences von Koenigswald (1960) divided the strewnfield into three zones—northern,

central, and southern—as indicated in Figure 7.

The continuity of the Indoaustralian strewnfield

is not entirely convincing. Tektites appear to be
16

FIGURE 7.—Distribution of Indoaustralian tektites, according

to Von Koenigswald (1960); our data indicate that the few

occurrences shown near the northwestern crest of Australia

probably represent transported specimens.

absent from .the northern half of Australia, and

none are known from New Guinea. In Indonesia

tektites are common only in central Java and on

Billiton Island; a few have been recorded from

Borneo and the island of Bunguran, two from the

Island of Flores, but none from Sumatra, Celebes,

Timor, or the smaller islands. In the Philippines

most of the tektite localities are on the island of

Luzon. If the whole strewnfield was produced by a

single shower, it was remarkably unevenly distributed.

The extent of the Indoaustralian strewnfield,

however, is considerably increased if the microtektites discovered by Glass (1967) in thirteen deepsea sediment cores from the Indian and western

Pacific Oceans are accepted as belonging to the

same event that produced the tektites. Glass (1972)

summarizes his conclusions as follows:

These glassy particles, called microtektites, represent a portion of the Australasian tektite-strewnfield as indicated by

their appearance, geographical occurrence, age of deposition,

age of formation (fission track age), petrography, physical

properties, and chemical compositions. Present theories of

tektite origin suggest that tektites were formed by impact

and thus deposited over the entire strewnfield instantaneSMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

ously (geologically speaking). Thus the Australasian microtektite layer provides a chronostratigraphic horizon throughout

much of the Indian Ocean including the area south of

Australia.

The age of this horizon, according to Glass, is

700,000 years BP, coincident with the BrunhesMatuyama magnetic reversal. However, this age is

inconsistent with the stratigraphic age of australites established by Gill (1970) and Lovering

et al. (1972). Not all tektite researchers accept

the identity of microtektites with tektites. Von

Koenigswald (1968) and others have suggested that

microtektites might be volcanic glass, and Baker

(1968a) has suggested that they are beads of plantsilica glass produced by forest fires. Baker and Cappadona (1972) point out that all well-preserved

australites, even the smallest, have their primary

forms modified by aerodynamic ablation, whereas

none of the microtektites show this feature. Microtektites have not been recorded from the Australian landmass; we searched for them in the

sedimentary horizon of the Pine Dam australites,

but found none.

Physical Properties and Chemical Composition

FORM

Australites are distinguished from other tektites

by their variety of well-defined forms, and unique

surface features produced by ablation during passage through the Earth's atmosphere. These features may be preserved in pristine perfection in

specimens recovered soon after exposure in humid

regions like the southwest coast of Victoria. In

arid areas in the Lake Torrens-Lake Eyre region

where we have collected, preservation is never so

perfect, even in freshly exposed specimens which

have not undergone transportation. They probably

suffered some sandblasting during burial, and subsequent exposure by recent deflation has further

affected them. Nevertheless, we have found some

remarkably fine specimens in these areas (Figure

8). In many localities transportation subsequent to

exposure has caused severe abrasion and removed

all or a large part of the original surface. However,

even these eroded specimens can be readily classified as to form.

Grant (1909) noted that the various shapes of

australites could all be derived from the five pri-
NUMBER 17 17

FIGURE 8.—Well-preserved australites showing a variety of forms from the Pine Dam area, South

Australia; the largest button is 25 mm in diameter.

mary forms which a mass of liquid is capable of

assuming. These primary forms are: (1) the sphere

(possible only with no rotation); (2) the oblate

spheroid (stable at low speeds of rotation); (3) the

prolate spheroid (stable, if at all, only at high

speeds of rotation); (4) the dumbbell (hourglass);

and (5) the apioid (pear- or tear-shaped). Fenner

(1938) recognized the sphere as the primary form

from which the secondary round forms, cores, buttons (sometimes flanged), and lenses, were derived.

Baker (1963b) has established the three principal

phases of shaping and sculpturing of tektites as primary, secondary and tertiary. The primary phase

was the generation of original shapes as described

by Grant (1909); the secondary phase that produced by ablational modification during passage

through the Earth's atmosphere; the third phase

that due to terrestrial weathering. He states that

"only in the australites and perhaps a few javanites

are all three phases distinctly evident. The secondary phase is so far unrecognized among other

tektites. In most tektite strewnfields the tertiary

phase has been especially dominant, tending to destroy the features of the other phases."

Baker (1959a, 1963b) has provided an extensive

discussion of the secondary forms of australites,
18 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 2.—Form analysis (expressed in percent unless noted otherwise) of australite collections

arranged by location (1, Pindera; 2, Motpena; 3, Beltana; 4, Pine Dam; 5, Mulgaria; 6, Peachawarinna; 7, Mulka; 8, Lake Yindarlgooda; 9, Hughes; 10, Nullarbor Plain [Fenner, 1934]; 11,

Charlotte Waters [Fenner, 1940]; 12, Port Campbell [Baker, 1956]; 13, Florieton [Mawson, 1958];

* = included with lenses; ** = included with ovals)

Forms

Buttons

Lenses

Round cores

Ovals

Oval cores

Boats

Canoes

Dumbbells

Teardrops

Correlation of Data

Total number of

whole forms

% of whole forms ...

Average weight (g) .

% of round forms ...

Number of fragments

% of fragments

1

20.7

10.3

17.2

6.9

10.3

20.7

3.5

3.5

6.9

29

67.4

4.7

48.2

14

32.6

19

9

6

1?

n

4

7

2

4

Q

,7

5

8

1

S

.9

190

42.0

3.6

59.0

262

58.0

3

18.7

6.0

34.6

3.0

4.0

19.7

2.0

5.0

7.0

101

47.6

5.0

59.3

111

52.4

?7

99

8

9

8

8

5

4

1

1

3

8

8

.0

121

39.2

3.2

57.7

188

60.8

5

28.2

19.7

11.3

9.9

8.5

4.2

2.8

8 4

7.0

71

34.8

2.3

59.2

133

65.2

6

5.1

12.8

12.8

18.0

20.5

18.0

0.0

5.1

7.7

39

55.7

3.2

30.7

31

44.3

7

19.0

26.9

12.7

3.2

1.6

19.0

3.2

8.0

6.4

126

49.2

2.8

58.6

130

50.8

8

1.0

13.8

35.7

11.0

10.1

17.4

1.0

7.3

2.7

109

83.2

5.1

50.5

22

16.8

9

18.0

56.0

2.0

2.0

0.0

8.0

4.0

0.0

10.0

50

40.0

0.8

76.0

75

60.0

10

13.8

54.9

*

8.4

8.6

4.1

3.5

6.7

1993

50.8

0.9

68.7

1927

49.2

11

13.3

63.4

*

14.4

A*

6.2

0.2

1.3

1.2

5137

72.6

6.5

76.5

1943

27.4

12

46.9

10.9

3.8

19.1

2.3

7.6

2.3

3.1

4.0

523

37.3

2.7

61.6

879

62.7

13

1.1

27.3

37.5

2.8

6.2

13.6

2.1

3.1

6.3

797

54.9

3.7

66.0

654

45.1

how they developed from the primary forms and

how they have been modified by processes of erosion and abrasion after they fell. Fenner (1934)

developed a comprehensive classification of australite secondary forms which has been used with

minor modifications by subsequent investigators.

In classifying our collections we have adopted

Fenner's system with a few alterations (Table 2).

Before setting out our classification it should be

mentioned that earlier investigators such as Suess,

Lacroix, and others listed by Baker (1959a, pp. 149

et seq.) envisaged the secondary shapes as being

derived from glass objects that were molten and

viscous as they traveled through the Earth's atmosphere with a rotary motion. This is incorrect.

It has been clearly shown by Baker (1959a) and

Chapman (1964) that all tektites from the Indoaustralian region descended through the Earth's atmosphere as rigid, nonrotating glass objects. The

secondary forms of australites, particularly the

unique flange, originated by the melting of surface

layers by heat generated through friction during

flight. The only time complete fusion of tektite

glass took place was in the primary forms at the

moment of formation.

The classification of forms used is as follows:

Buttons: round forms, when well preserved showing a

partial or complete flange and flow ridges on the forward

surface. Data on 17 well-preserved australite buttons from

Motpena, South Australia, giving weights, radius of curvature and other dimensions, and nature of flow ridges are

set out in Table 3, and the specimens are shown in

Figure 9.

Lenses: biconvex round forms with a sharp rim. It may be

difficult to distinguish a button which has completely lost

its flange from a lens. Lenses are smaller than buttons

because they represent a further stage of development
#

II

16

12

17

13 14

10

16 17

13

10

15

FIGURE 9.—Anterior and posterior views of seventeen australite buttons from Motpena, South

Australia; dimensions, weights, and other data are given in Table 3.
20 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 3.—Data on 17 well-preserved australite buttons from Motpena Station, South Australia

(weights in grams; radius of curvature and other dimensions in millimeters; C = concentric;

S.C. = spiral clockwise; S.A. = spiral anticlockwise)

Specimen

number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

Average

Range

Weight

5.482

4.853

3.918

4.155

4.107

4.249

4.735

3.948

3.975

5.100

4.234

5.461

2.469

2.980

4.322

2.302

3.004

4.078

3.044-

5.482

Radius of

Front

face

11.2

12.0

11.6

12.0

11.4

12.0

11.0

11.0

11.0

11.4

11.0

11.2

11.2

11.2

10.6

11.1

11.4

11.3

10.6-

12.0

curvature

Rear

face

13.8

11.4

13.2

13.6

10.8

11.0

10.8

10.4

10.2

9.6

11.8

9.6

10.4

10.2

9.6

9.8

9.8

10.9

9.6

13.8

Overall

diameter

23

22

22

22

23

22

23

22

20

24

23

23

20

20

21

20

22

22

20-

24

Diameter

of core

16

17

16

18

15

17

17

15

15

17

15

18

15

15

15

14

15

16

14-

18

Width of

flange

3.2

2.5

3.2

2.1

4.0

2.5

3.0

4.0

2.5

3.5

4.0

2.5

2.5

2.9

3.0

4.0

3.5

3.0

2.1-

4.0

Specific

gravity

2.449

2.455

2.455

2.471

2.456

2.449

2.472

2.468

2.477

2.456

2.449

2.460

2.460

2.455

2.445

2.468

2.455

2.458

2.445-

2.477

Nature of

flow ridges

C

C

C

S.C.

S.C.

C

S.A.

S.C.

S.A.

C

C

S.A.

S.A.

S.A.

S.C.

S.C.

S.C.

Average

Range

5.

1.

9.

24 australite

337

916-

342

12.

8.

13.

buttons

16

48-

69

from

10.

6.

13.

Port

19

39-

55

Campbell

22.5

16.5-

26

(Baker,

-

-

1967b)

3.5

3.0-

4.5

2

2

2

.400

.373-

.429

through extreme ablation causing the complete loss of the

flange during flight. There is a way in which lenses can

be distinguished from flangeless buttons; Baker (1956)

has introduced the term "flange band." This refers to

vestiges of smooth areas that are sometimes seen at the

edge of the posterior surface of round forms. Baker regards "flange bands" as representing the original surfaces

of union between the body of the australite and the flange

(now completely removed).

Round cores or "bungs": the term "bung" is an indefinite

one and applies to large round cores. Cores are thicker

and heavier than buttons and originate in two ways:
NUMBER 17 21

The first is the flaking away of unstable portions of

equatorial regions of primary spheres in process of ablation during atmospheric flight. Baker (1956) considers that

these spheres were twice as large as those that gave rise

to buttons and lenses. The flaking occurred in the area of

greatest frictional drag. The best of such cores shows

striking markings on the equatorial zone as though caused

by chipping, with no sign of weathering. In general the

larger cores ("bungs") form in this way (Baker, 1959a,

pi. X, and 1969a, pi. 7). The second way that cores

are formed was suggested by Chapman (1964), who introduced the concept of an aerothermal stress shell. This

develops during the latter stages of flight of any of the

primary forms as the front face is rapidly cooled to temperatures below the strain temperature of the tektite

glass. Under certain conditions depending on size, entry

trajectory, and tektite composition, and aided by weathering and abrasive processes, the "shell" may partly spall

off revealing the original stress profile with flange intact

and the inner core-shaped mass (Figure 10 and Chapman, 1964, fig. 4). On further weathering the two parts

may become completely detached. Fenner (1935) illustrates

this method of formation of a core. In general, smaller

cores originate in this way.

(Buttons, lenses, and round cores are derived from primary

spheres.)

Ovals: similar to buttons, but oval instead of round; the

australite given by Sir Thomas Mitchell to Charles Darwin

is a well-preserved flanged oval (Figure 1).

Oval cores: These form in exactly the same way as round

cores.

Boats: more elongate than ovals, with straight parallel

sides and rounded ends.

Canoes: similar to boats, but smaller, narrower, and pointed

at both ends.

Dumbbells: a self-explanatory term used by some observers

even when the constriction at the "waist" is barely perceptible; derived from the primary dumbbell form.

Teardrops: a self-explanatory term. According to Chapman

(1964) these shapes result when a primary mass of molten

glass of very high viscosity is disrupted into many component blobs on cooling soon after initial formation. These

component blobs would tend to assume the primary

apioid shape. Chapman (1964) has pointed out the tearFIGURE 10.—Photographs illustrating the formation of round and elongate cores by spallation of

the outer flanged aerothermal stress shell. The specimens are from Mt. Victory Well, Lake Torrens region, South Australia.
22 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

drop shapes are much more common in the northern

region of Indoaustralian strewnfield than in Australia.

Chapman, in this paper, has postulated that the temperature of formation must have become progressively lower

as one proceeds from southeast Australia, through southwest Australia, to the northwestern, i.e., the Indomalaysian, region of the strewnfield. Under the heading of

teardrops Baker (1959a, 1963b) includes forms such as

pear shapes, stopper shapes and aerial bombs.

(All of the above forms, excepting cores of all shapes, and

lenses, may have flanges, although cores may show "flange

stumps," the very last remnants of a complete flange.)

Bowl-, disc-, and plate-forms: These are very small, thin,

and fragile forms (Baker, 1963a) and are so rare that we

do not regard them as statistically significant. They are

not included in Table 2 (Form analyses of australite

collections). Data on small fragile forms collected by us

are given in Table 4 and the specimens are shown in

Figure 11. These may be the very last remnants of almost

completely ablated australites that entered the atmosphere

as smaller than average-sized primary spheres (Baker 1958).

Baker (1940) has also suggested that these fragile forms

may have originated as the flakes detached, through frictional drag in the equatorial zones, from large round and

elongate primary forms. Baker suggests that these flakes

TABLE 4.—Data on 20 small australites from the Pine Dam area (weight in grams; dimensions in

millimeters)

Specimen

Number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Type

oval bowl

round bowl

oval bowl

elongate bowl

lens

oval bowl

(chipped)

oval bowl

lens

oval bowl

(infolded)

canoe

round bowl

flanged button

canoe

teardrop

teardrop

lens

flanged oval

flanged button

(chipped)

teardrop

lens

Weight

0.0408

0.0675

0.0896

0.0997

0.1186

0.1315

0.1344

0.1373

0.1382

0.1397

0.1436

0.1496

0.1501

0.1536

0.1920

0.2285

0.2486

0.2512

0.2858

0.3265

Specific

Gravity

2.403

2.431

2.449

2.449

2.460

2.450

2.449

2.439

2.448

2.468

2.465

2.458

2.455

2.447

2.469

2.439

2.459

2.458

2.461

2.460

Length

6

6

8

9

7

9

9

7

9

11

6

9

14

11

10

8

11

13

11

10

Width

5

6

5

4

7

7

7

5

5

5

6

9

5

7

6

8

9

13

Depth
NUMBER 17

#

8

10 11 12

13 14

15

16

17

18

19

20

FIGURE 11.—Twenty bowl-, disc-, and plate-form australites from the Pine Dam area, South

Australia; dimensions, weights, and specific gravities are given in Table 4.
24 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

may still have been travelling with sufficient velocity to

have suffered further ablation and thus have assumed

regular shapes.

All complete collections such as those made by

us in different areas and by Baker in southwestern

Victoria contain many fragments, usually exceeding in number the well-preserved complete forms.

There was a lack of fragments in some large collections made in earlier periods. Untrained personnel

collecting australites would tend to concentrate on

well-preserved, relatively large forms, rather than

these smaller examples.

Fragmentation occurred after the australites

landed on the ground. Australite glass is quite

tough and the force of impact would have been

quite gentle, since they would have lost their

initial high velocity and would be falling under

the influence of gravity. Even on hard ground it is

unlikely that impact would have caused fracturing.

The aerothermal stress shell and other stresses result from the australite being in a state of strain.

Such factors as the extreme diurnal temperature

variations in semi-arid interior Australia, and the

abrasive action of wind-blown sand, and water in

times of infrequent but nonetheless violent flash

floods, would cause splitting and spalling along

lines of weakness created by the stresses.

Pronounced channel-like lines of parting extending deep into many australites are known as

"saw-cuts" and in all collections there are many

examples of complete forms on the verge of breaking up into numerous fragments due to pronounced development of this feature (Figure 12).

Fenner (1934) first suggested the term "saw-cuts"

so that no possible implication as to their origin

would be conveyed. Baker (1959a) considers that

they often form along flow-line structures and most

likely represent lines of easiest etching.

FIGURE 12.—Australites showing "saw-cuts"; the largest specimen (25 mm long) is from Mulgaria, the other two from near Beltana, in the Lake Torrens region of South Australia.
NUMBER 17 25

FORM ANALYSIS

For those of our collections which were numerous enough to be statistically significant we analyzed

the form distribution. The results are summarized

in Table 2, along with comparable data from other

investigators. Round types (buttons, lenses, and

round cores) predominate in all the collections

analyzed. This substantiates the findings of Chapman (1964) who, as already mentioned, noted this

fact in contrast to the predominance of teardrop

shapes toward the northwest of the entire Indoaustralian strewnfield. Round types in collections

from the Lake Torrens localities and Mulka range

from 57.7% to 59.3%; percentages for Pindera and

Peachawarinna, respectively, are 48.2% and 30.7%.

The latter two collections are probably too small

for this statistical analysis. The figures for Port

Campbell deserve comment. There is a high 61.6%

for total round forms, which comprise a high

46.9% of buttons and a low 10.9% for lenses and

3.8% for round cores. These figures, particularly

the high percentage of buttons, may reflect the excellent state of preservation in this region or the

close and meticulous examination carried out by

Baker (1956) who, for example, distinguishes buttons from lenses and small round cores by the

presence of "flange bands," a feature that might

escape investigators of collections from other localities. As one would expect, high percentages of

round cores ("bungs"), the larger forms, are

present in collections with high average weight

(Beltana, Lake Yindarlgooda, and Charlotte Waters).

It is particularly interesting to note the close correspondence between the form analyses of the

Hughes and Nullarbor Plain collections. Hughes

is on the Nullarbor Plain, and we made the collection in 1965; the Nullarbor Plain collection

described by Fenner (1934) was made by Mr.

W. H. C. Shaw, an officer of the Commonwealth

Post and Telegraph Department stationed in this

area in the period 1910-1930.* The distribution of

forms is similar and the average weight is essentially identical. This confirms the small size of

*Fenner (1934) quotes Shaw as stating that the majority

of these tektites were found in the vicinity of Israelite Bay,

near the western margin of the Nullarbor Plain.

australites on the Nullarbor Plain compared to

those of other regions. Of the elongate forms, ovals

and boats are fairly common, whereas dumbbells,

teardrops and canoes are present in lesser numbers.

Canoes are smaller and more fragile than the other

forms and therefore are destroyed more readily by

natural forces.

WEIGHT

The high average weight of the forms from Lake

Yindarlgooda, Charlotte Waters, the hitherto unmentioned Mt. Davies area, and Beltana is due to

an unusually high percentage of round cores. From

the Lake Yindarlgooda collection this may result

from geological conditions. There the australites

are washed on to the lake floor from lag gravels on

higher ground and transportation has probably destroyed many of the smaller forms. The same may

apply to the Mt. Davies area in the far northwest of South Australia, which is an area of high

relief. We have inspected a large collection (about

2,000) obtained by the South Australian Department of Aboriginal Affairs from aborigines in this

area. These are notably large and average about

the same as those from Charlotte Waters. The

Charlotte Waters collection examined by Fenner

(1940) was made by John W. Kennett when he

was in charge of the police station there, and many

of the specimens were collected by aboriginals. Unfortunately there is no detailed description of the

occurrence of australites in this locality. As noted

in Table 2 australites from the Beltana area are

larger than usual (average weight 5 grams). There

is a concentration of large specimens on the eroded

surface of the Motpena paleosol. The large round

core (33.3 grams) and the large dumbbell (16.1

grams) listed in Table 5 came from here. When

one compares the weights of different forms (Table

5) some interesting features are seen. The largest

specimens, as might be expected, are the cores. The

36-gram oval core from Lake Yindarlgooda is the

largest specimen we have ever found. Australites

weighing more than 60 grams are quite rare. A

list of those known to us (numbering 121) is given

in Table 6, and their distribution shown in Figure

13. Data from Fenner (1955), Baker (1969a and

1972), and Cleverly (1974) are incorporated in this

table. Figure 13 further confirms the evidence of

Cleverly (based on australites of mass greater than
26 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 5.—Maximum and minimum weights in grams for all

australites collected, arranged by form

Form

Buttons

Lenses

Round cores

Ovals

Oval cores

Boats

Dumbbells

Teardrops

Canoes

Maximum

5.7

4.6

33.3

13.4

36.0

16.9

16.1

9.4

1.5

Minimum

0.5

0.1

1.0

0.7

1.5

0.9

0.5

0.7

0.5

100 grams) of a remarkable concentration of large

australites in the southwestern corner of Western

Australia, extending as a belt towards the northnortheast. A minor concentration of large australites is evident in western Victoria, extending

northwest to Finke in the Northern Territory (although no australites weighing more than 40 grams

are known to us from the central part of this streak

in the Lake Torrens region). Cleverly (1974) interpreted the distribution of large australites as indicating a concentration in areas distant from the

northern boundary of the strewnfield, suggesting

the possibility of a mass gradient away from this

boundary. Cleverly considers this to imply a direction of flight southwards from the northern

boundary of the strewnfield, at variance with the

conclusion of Chapman (1971), who deduced a generally south-north direction for australite flight

paths.

The large australites whose locations are plotted

in Figure 13 define two linear belts which intersect

at approximately 19°S,129°E. This is a remote area

about 100 miles southeast of Halls Creek. The

Halls Creek 1:1 million map sheet shows an oval

ring of hills with a major east-west axis about 30

miles long in this area; geological maps show a

rim of upturned Proterozoic quartzites surrounding a core of highly disturbed Archean rocks, suggesting an impact structure. The significance, if

any, of this feature to the australite problem remains to be investigated.

The fragile disc-, plate-, and bowl-shaped forms

have been described in detail and illustrated by

Baker (1963a, 1964b) from the Port Campbell region. The smallest one was an oval shallow bowl

weighing 0.065 grams. Baker and Cappadona

(1972) have described the smallest complete australite ever found. It is from 6 miles north-northeast

'

zs\

\

' 3 0

•35

,

j

IIS

•

•

.•.i \ • •.

120

#

•

m

• •

#

•

k

» = >200 grams

• = 100-200 graras

• = 60-100 grams

125 130

•

\ /

% /

133

Q•

V

%

a •

•

•'/•A

&^

X

140

•

•

\ s

•

• \

• •

• •

•

•

143 '*S'

\

Jy

f

i

1i

It i

k

ISO

i-

\

FIGURE 13.—Geographical distribution of large australites listed in Table 6.
TABLE 6.—Weight, form, and present location of large australites (over 60 grams), listed in order

of decreasing weight (AM = Australian Museum, Sydney; BM = British Museum (Natural History), London; BMR = Bureau of Mineral Resources, Canberra; GCLWA = Government

Chemical Laboratories of Western Australia, Perth; GMM = Geological and Mining Museum,

Sydney; GSWA = Geological Survey of Western Australia, Perth; NMV = National Museum of

Victoria, Melbourne; SAM = South Australian Museum, Adelaide; WAM = Western Australian

Museum, Perth; WASM = Western Australian School of Mines, Kalgoorlie; UA = University of

Adelaide, Department of Geology; UM = University of Melbourne, Department of Geology:

references without a date are personal communications; WHC = W. H. Cleverly; WHC & JMS

= W. H. Cleverly & J. M. Scrymgour)

Locality

Notting, W.A.

Newdegate, W.A.

near Warralakin, W.A.

near Kondinin, W.A.

Lake Yealering, W.A.

Karoonda, S.A.

Lake Ballard, W.A.

near Babakin, W.A.

Narrogin or

Narembeen, W.A.

near Notting, W.A.

near Ongerup, W.A.

Cuballing, W.A.

near Toolondo, Vic.

Graball, W.A.

Corrigin, W.A.

near Chillilup, W.A.

Western Victoria or

Teetulpa, S.A.

between Narrogin and

Merredin, W.A.

near Ongerup, W.A.

near Charlotte Waters

near Corrigin, W.A.

near Eucla, W.A.

Port Campbell, Vic.

near Balaklava, S.A.

near Goroke, Vic.

Lake Grace, W.A.

Lake Grace, W.A.

near Kulin, W.A.

Coordinates

32°27\

33°06\

31°08',

32°30',

32°36\

35°09',

29°21',

32°10\

- -

32°27',

33°48\

32°49',

36°58',

32°02\

32°22',

34°29',

-

-

33°52',

26°10\

32°21',

31°40',

38°37',

34°02\

36°45',

33°06',

33°06',

32°40',

118°14'

119°02'

118°41'

118°07'

117°37'

139°54'

120°36f

118°06'

-

118°05'

118°28'

117°11'

142°05'

118°34'

117°54'

118°25f

-

-

118°21'

134°50'

117°52'

128°51'

143°02'

138°20'

141°36'

118°28'

118°28'

118°26'

Weight

(grams)

437.5

243.1

238.0

233.9

218.6

207.9

200.3

197.2

194.8

194.4

184.1

176.0

173.6

168.3

168.0

167.3

154.0

152.0

151.3

149.3

147.0

142.0

141.6

141.0

135.1

134.5

132.7

131.5

Core

shape

broad oval

round

broad oval

broad oval

round

narrow oval

broad oval

round

broad oval

round

round

dumbbell

boat

round

round

round

round

round

dumbbell

round

round

round

boat

broad oval

(frag.)

oval

round

round

narrow oval

Where

preserved

WAM 13238

(cast)

WAM 12318

WASM 8925

H. Biggin

WAM 4455

SAM T1159

L.P. Berryman

WAM 13364

WAM 12992

WAM 12884

WAM 12293

GSWA R2024

NMV E4753

WAM 12843

GCLWA 1678

WAM 13237

(cast)

K. Blackham

WAM G8978

GSWA

G. Latz

WAM 3491

lost

NMV 11402

SAM G1391

NMV 11401

AM DR 7533

AM Clarke

WAM 12264

Reference

Cleverly, 1974

ii

ii

ti

II

Fenner, 1955

Cleverly, 1974

WHC

Cleverly, 1974

it

Baker, 1972

Cleverly, 1974

II

WHC

Cleverly, 1974

WHC & JMS

Cleverly, 1974

Fenner, 1934

Baker, 1969a

WHC & JMS

Baker, 1969a

Cleverly, 1974

WHC

Cleverly, 1974
28 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 6.—Continued

Locality

Penwortham, S.A.

Kalgarin, W.A.

Hamilton Station, S.A.

Koralta Station, NSW

Wickepin East, W.A.

Lake Buchanan, W.A.

Lower Norton, Vic.

Laing, Vic.

Narembeen, W.A.

Babakin, W.A.

near Karoonda, S.A.

Lake Wallace, Vic.

Moulyinning, W.A.

Norseman, W.A.

Central Australia

Brookton, W.A.

E. Goldfields, W.A.

Narembeen, W.A.

Charlotte Waters, N.T.

Salmon Gums, W.A.

near Kurnalpi, W.A.

Karonie, W.A.

William Creek, S.A.

Muloorina, S.A.

near Kalgoorlie, W.A.

Nullarbor Plain

Rosanna, Vic.

Lowaldie, S.A.

Kulin, W.A.

Kaniva, Vic.

Lake King, W.A.

Coordinates

33°55',

32°30\

26°40\

31°27',

32°45',

25°30',

36°47',

38°22',

32°04',

32°07',

35°04',

37°02',

33°14',

32°12',

-

32°22',

-

32°04',

25°55',

33°03',

30°28',

30°59\

28°55?,

29°10',

30°49',

-

37°45\

35°04\

32°42',

36°33',

33°05',

138°38'

118°42'

135°05'

142°18'

117°44'

123°00'

142°04'

142°49'

118°23'

118°01'

139°57'

141°18'

117°56'

121°47'

-

117°02'

-

118°50'

134°55'

121°44'

122°09'

122°39'

136°21'

137°51'

121°29'

-

144°58'

139°59'

118°08'

141°17'

119°33'

Weight

(grams)

132.0

126.8

121.2

118.0

116.9

116.1

115.9

115.8

114.6

113.1

113.0

111.3

111.2

110.6

110.1

109.8

108.3

107.5

103.0

102.4

101.1

100.8

100.7

99.6

98.1

98.0

97.1

96.0

95.7

95.9

95.7

Core

shape

round

broad oval

broad oval

round

broad oval

round

round

dumbbell

broad oval

broad oval

round

round

round

round

boat

round

round

narrow oval

round

round

broad oval

broad oval

broad oval

(frag.)

oval

-

oval

dumbbell

dumbbell

round

boat

round

Where

preserved

L. French

R. Pugh

SAM T1392

BMR R18277

F. Davis

WAM 12960

NMV E273O

A. Halford

GSWA 1/5327

SAM T191

-

NMV E1986

WAM 10613

SAM T427

GMM 17408

WAM 12090

WASM 10199

WASM 8950

?

WASM 9421

C.B. Jones

SAM T509

G. Hume

SAM T1287

BM 1916, 372

SAM T520

NMV 11365

SAM T1296

WAM 12316

UM 3045

A.J. Thompson

Reference

WHC & JMS

Cleverly, 1974

WHC & JMS

WHC & JMS

Cleverly, 1974

»

Baker, 1969a

Cleverly, 1974

»

Fenner, 1955

Baker, 1969a

Cleverly, 1974

it

WHC & JMS

Cleverly, 1974

ii

WHC & JMS

Cleverly, 1974

II

WHC & JMS

D.W.P. Corbett

J. Hall

Fenner, 1955

A.W. Beasley

D.W.P. Corbett

D. Merrilees

Baker, 1959a

WHC
NUMBER 17 29

TABLE 6.—Continued

Locality

Warrnambool, Vic.

Edjudina Station, W.A.

Horsham, Vic.

Wellington, S.A.

Hexham Station, Vic.

Charlotte Waters, N.T.

near Cockburn, S.A.

near Edenhope, Vic.

Todmorden, S.A.

Victoria

Finniss Springs, S.A.

Corop, Vic.

Jubuk, W.A.

Baandee, W.A.

near Corrigin, W.A.

Lorquon, Vic.

near Renmark, S.A.

E. Goldfields, W.A.

Ernabella area, S.A.

near Corrigin, W.A.

Laverton, W.A.

Diamantina R., S.A.

Pindera N.S.W.

Cheyne Beach, W.A.

Leonora, W.A.

near Muntagin, W.A.

near Merredin, W.A.

Frances, S.A.

near Boorabbin, W.A.

Maroona, Vic.

Wongawol, W.A.

Nungarin, W.A.

Coordinates

38°23',

29°

36°45T,

-

-

25°55\

32°10',

37°04\

27°04',

-

29°35',

36°28\

32°20',

31°35',

32°

36°10',

34°10',

-

26°

32°

28°49\

-

29°27',

34°21',

28°54',

31°

31°31f,

36°41',

31°14',

37°25\

26°07',

31°11',

142°03'

122°

142°15'

-

-

134°55?

140°58T

141°20'

134°49'

-

137°28'

144°48'

117°38'

117°58'

117°

141°45'

140°45'

-

132°

117°

122°25'

-

142°29'

118°57'

121°20'

118°

118°07'

140°59'

120°21'

142°52'

121°56'

118°06?

Weight

(grams)

94.0

92.6

90.8

90.5

90.3

90.0

89.8

89.6

89.0

88.9

88.8

88.5

86.8

86.7

85.7

83.7

83.5

83.4

80.0

79.5

78.1

78.0

77.5

76.7

75.3

75.1

75.0

74.5

74.5

74.3

74.2

73.6

Core

shape

dumbbell

round

round

- -

- -

- -

oval

round

dumbbell

- -

boat

boat

broad oval

round

round

boat

teardrop

round

oval

round

oval

teardrop

oval

round

round

round

round

round

-

boat

teardrop

round

Where

preserved

SAM T1158

I.R. Williams

NMV 5204

BM 1935, 252

BM 1926, 393

G. Hume

D.H. McColl

NMV 16869

SAM .T638

BM 1927, 1167

SAM T579

UM 3046

WAM G7566

WAM 12176

N. Rendall

NMV E336

SAM T91

WASM 10306

C. Collyer

N. Rendall

WAM 12167

SAM T92

F. Nicholls

WAM 12972

SAM T508

WASM 10545

WAM 12935

SAM T28

M. Alexander

NMV E1270

WAM ESS22

WAM 12145

Reference

Fenner, 1955

WHC

Baker, 1961c

J. Hall

"

D. H. McColl

II

A.W. Beasley

Fenner, 1955

J. Hall

Fenner, 1955

Baker, 1959a

Cleverly, 1974

it

WHC

A.W. Beasley

Fenner, 1955

W.H. Cleverly

D.H. McColl

WHC

D. Merrilees

Fenner, 1955

R.O. Chalmers

D. Merrilees

D.W.P. Corbett

WHC

D. Merilees

D.W.P. Corbett

WHC

A.W. Beasley

Cleverly, 1974

D. Merilees
30 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 6.—Continued

Locality

Wooganellup, W.A.

Nullarbor Plain ?

near Morgan, S.A.

Merino, Vic.

Kurnalpi, W.A.

Mount Barker, W.A.

Lake Yindarlgooda, W.A.

Nyabing, W.A.

Crown Point, N.T.

Gindalbie, W.A.

Coonana, W.A.

near Narembeen, W.A.

near Esperance, W.A.

near Lameroo, S.A.

near Yunta, S.A.

near Kalgoorlie, W.A.

Kalgoorlie, W.A.

near Maitland, S.A.

near Boorabbin, W.A.

near Florieton, S.A.

Lake Grace, W.A.

Balaklava, S.A.

near Agnew, W.A.

Charlotte Waters, N.T.

Balaklava, S.A.

Central Australia

Eucla, W.A.

Bullaring, W.A.

Babakin, W.A.

near Gnowangerup, W.A.

Coordinates

34°

-

33°50',

37°45',

30°32',

34°36\

30°38',

33°31\

25°40',

30°

31°

32°33',

33°

35°28',

32°21',

30°

30°49\

34°26',

31°

33°49',

33°06',

34°08',

28°00',

25°55',

34°08',

-

31°40',

32°30',

32°11',

33°52',

117°

-

139°50'

141°35'

122°14'

117°37f

121°57'

118°10'

134°40'

121°

123°

118°13'

121°

140°26'

139°20'

121°

121°29'

137°40'

120°

139°25'

118°23?

138°24'

121°10'

134°55'

138°24'

-

128°51

117°44'

117°58'

117°53'

Weight

(grams)

73.1

72.5

72.3

71.8

71.3

70.7

69.5

69.1

68.7

68.2

67.6

66.7

66.2

66.0

65.0

64.9

64.7

64.3

64.1

63.6

63.5

63.0

62.9

62.5

62.2

62.0

62.0

61.0

60.8

60.6

Core

shape

round

oval

oval

dumbbell

round

round

-

round

boat

-

-

dumbbell

-

oval

round

round

boat

dumbbell

-

oval

round

round

boat

oval

round (frag.)

round

boat

round

round

round

Where

preserved

WAM ESS 86

SAM T1O77

NMV E3965

NMV El236

WASM 2215

WAM 10643

CBC Jones

WAM 12885

SAM T129

R.L. Jones

CBC Jones

WAM 12321

WAM ESS 1

R.G. Kimber

UA 18361

(missing)

UA 18357

SAM T547

G. Young

WAM 12802

UA

WAM 10549

SAM T128

WAM 12110

SAM T232

SAM

SAM T1070

SAM T332

WAM 10671

WAM 12942

WAM 12163

Reference

WHC

D.W.P. Corbett

Baker, 1968b

A.W. Beasley

W.A. Cleverly

D. Merrilees

WHC

D. Merrilees

Fenner, 1955

WHC

WHC

D. Merrilees

WHC

D.H. McColl

D.W.P. Corbett

D.H. McColl

WHC

D.H. McColl

D. Merrilees

D.W.P. Corbett

D. Merrilees

D.W.P. Corbett

D.H. McColl

D.W.P. Corbett

»

D. Merrilees

••

ii
NUMBER 17 31

of Princetown on the south coast of Victoria. It is

an oval bowl and weighs 0.025 grams. Since these

forms are extremely fragile few survive lengthy

exposure to the elements, but we have collected

some in the Lake Torrens region at Mulgaria, Mt.

Victory Well, and Pine Dam. A few have been

found in the Lake Eyre region at Peachawarinna.

A particularly productive spot was a small area in

one of the claypans near Pine Dam. We were

somewhat puzzled by a remarkable concentration

of small australites and australite fragments over a

limited area near the middle of the pan. We noted

that this area was a few inches higher than the

surrounding pan floor, but the significance was not

realized until later, when during laboratory experiments it was found that these thin fragile forms

actually float in water because of the surface tension. Occasional rains flooding the pans with a few

inches of water presumably concentrated these

fragile forms by floating them on to the dry areas

slightly higher than the rest of the pan floor. The

smallest was an oval bowl weighing 0.0408 grams

and the largest was a lens weighing 0.3265 grams.

In Table 4 the weights and dimensions of twenty

of these fragile forms from this area are listed, and

they are illustrated in Figure 11. In these fragile

forms the central core is always much reduced in

volume relative to the secondarily developed circumferential flange.

SPECIFIC GRAVITY

Summers (1913), on the basis of rather sparse

data, recognized a significant regional trend in the

specific gravities of australites. He wrote:

I have stated elsewhere that there seemed to be a somewhat

provincial distribution of the australites in respect to composition and specific gravity. As one would naturally expect,

the specific gravity of a specimen, except where modified by

the occurrence of occluded vesicles, gives a good indication

of the composition of the australite. My present impression

is that the less acid forms are concentrated along the borders

of the belt and that the acid ones are commoner along the

central line running from Melbourne towards the Lake Eyre

district.

This prescient suggestion apparently fell into

limbo. Some thirty years later, Baker and Forster

(1943) published an extensive study of the specific

gravities of 1,086 australites. From their results

they decided that the specific gravity values show

a definite gradient from east to west. They wrote:

"In graph 19, the silica percentage in australites is

seen to be highest in those forms with the lower

specific gravities. From this, and the specific gravity

values set out in Table 5, it is concluded that less

acid forms occurring in the western portions of

Australia give way to more acid varieties in the

eastern parts of the australite strewnfield." And

in a later section they used their data to deduce

the manner of formation of the strewnfield: "Since

the specific gravities of australites show a significant decrease from north of west to south of east

across Australia, the extraterrestrial body from

which the australites were shed traversed the island

continent from north of west to south of east."

However, despite these categorical statements, it

now appears that Summers' suggestion of a central

low-density belt is more nearly correct, and this has

been confirmed by McColl and Williams (1970).

Figure 14 presents the specific gravity distribution recorded by Baker and Forster. They found

specific gravities varying from 2.30 to 2.50, with

most of the values (94.5%) occurring between 2.36

and 2.47. The values show a single sharp peak at

2.40. Later work has shown that these data present

a distorted picture of specific gravity distribution

over the whole strewnfield, since the great majority

of the specimens they measured came from the belt

of low specific gravity extending from western Victoria through eastern South Australia to Lake Eyre

and beyond. Chapman et al. (1964) measured specific gravities of large numbers of specimens from

individual localities in Australia, and their results

are summarized in Table 7, along with data for

our collections, and those for some of the larger

localized collections measured by Baker, and Baker

and Forster. (For the latter the figure in the

"Peaks" column is the mean value because they

did not plot the individual data.)

The data in Table 7 show that the specific

gravity range at any one locality is not particularly

distinctive, but the specific gravity distribution, as

established by the peak or peaks, is. Three distinctive geographical groupings appear (Figure 3):

1. A single peak at 2.45-2.47, which characterizes all the Western Australian localities, plus

their extension on the Nullarbor Plain into South

Australia, and at Lake Wilson in the extreme

northwest of South Australia; this peak also characterizes collections from northeast South Australia
32 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

150-

140-

130

2-30

FIGURE 14.—Specific gravity distribution for 1086 australites

from different parts of Australia (Baker and Forster, 1943).

and adjoining localities in Queensland and New

South Wales.

2. A single peak at 2.40-2.42, characteristic of

Port Campbell and other localities in western Victoria; similar populations are present in southeastern South Australia (e.g., Oakvale, Morgan,

Mannahill).

3. Two peaks, one at 2.40-2.41 and one at

2.45-2.46, characteristic of localities in the Lake

Torrens-Lake Eyre region. This region of twocomponent populations does not seem to extend

north beyond Macumba to Charlotte Waters, nor

northeast beyond Cooper Creek to Mulka and

Mungeranie. The 2.40 peak is not present in the

Motpena collection, although this belongs geographically with the other localities in the Lake

Torrens area.

The simplest explanation of this geographical

distribution is clearly the early suggestion of Summers that a band of tektites of low specific gravity

extends from western Victoria to the Lake Eyre

district, this band being apparently superimposed

on a widely distributed population of significantly

higher specific gravity. The two-population nature

of the australites from the Lake Torrens-Lake

Eyre region is well shown in the specific gravity

distribution plot for 761 australites which we collected in this region in 1964 (Figure 15). We are

indebted to Dr. Dean Chapman for the specific

gravity determinations incorporated in this plot.

It is difficult to obtain meaningful data for the

northeastern part of the strewnfield, comprising

localities in eastern New South Wales and southeastern Queensland. Our searches in these regions

have been unproductive, and specimens are rare in

collections. However, Chapman and Scheiber

(1969) analyzed two specimens from Liverpool and

Uralla, in eastern New South Wales; these have

high specific gravities (2.489, 2.482) and low SiO2

contents (66.9%, 68.1%).

REFRACTIVE INDEX

Numerous measurements of the refractive index

of australites have been reported in the literature,

and we have made several during the course of

this investigation. Within any australite some variability of refractive index is usually found; this

variability can readily be detected in thin sections

(Figure 16), which show complex flow patterns

marked by schlieren with slightly differing refractive indices. The variability within a single australite can be of the order of 0.003; however, in

making refractive index determinations by the im-
NUMBER 17

TABLE 7.—Specific gravities and peak(s) for localized collections of australites (* = mean value,

not peak)

Locality

Granite Peak

Earaheedy

Kalgoorlie area

Nullarbor Plain

Hughes

Ooldea

Wingellina

Lake Wilson

Charlotte Waters

Macumba

William Creek

Mulka

»

Mungeranie

Peachawarinna

Mulgaria

Pine Dam

Beltana

Motpena

Mannahill

Oakvale

Morgan

Port Campbell

Pindera

Durrie

Cuddapan

Number of

Specimens

46

85

420

634

240

56

135 ...

986

28

420

29 ...

19

96

259

275

99

38

45

87

75

67

123

97

31

148

78

555

155

99

82

Specific Gravity

Range

2.402-2.458

2.420-2.459

2.385-2.485

2.390-2.475

2.413-2.476

2.428-2.475

2.391-2.491

2.395-2.505

2.415-2.498

2.385-2.495

2.392-2.484

2.380-2.466

2.367-2.472

2.355-2.485

2.365-2.557

2.398-2.465

2.402-2.481

2.380-2.468

2.376-2.474

2.368-2.476

2.388-2.470

2,395-2.481

2.370-2.459

2.386-2.450

2.348-2.437

2.355-2.465

2.305-2.465

2.270-2.470

2.385-2.487

2.390-2.488

CSl 2

2CSl 2

Peak(s)

2.452

2.453

2.455

2.445

2.459

2.457

2.470

2.465

2.475

2.445

2.439*

.395, 2.440

2.426*

2.435

2.440

2.440

2.445

.408, 2.453

.401, 2.458

.395, 2.462

405, 2.445

2.445

2.419

2.409

2.405*

2.405

2.397*

2.450

2.440

2.459

Reference

Mason, unpublished

»

Chapman et aL, 1964

••

Mason, unpublished

"

Baker, 1961a

Chapman et al., 1964

Mason, unpublished

Chapman et al., 1964

Baker and Forster, 1943

Mason, unpublished

Baker and Forster, 1943

Chapman et al., 1964

Baker, 1969b

Mason, unpublished

»

Baker, 1968b

Chapman et al., 1964

Baker and Forster, 1943

Chapman, unpublished

Mason, unpublished

••
34 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

2.42 2.43 2.44

SPECIFIC GRAVITY

FIGURE i5.—Specific gravity distribution for 761 australites from the Lake Torrens-Lake Eyre

region; specific gravity determinations by Dr. Dean Chapman.

mersion method it is usually possible to arrive at

a reasonable mean value.

Extensive series of measurements of refractive

index and specific gravity on australites have been

reported by Baker (1959a), Chao (1963), and Chapman and Scheiber (1969). The data of Chapman

and Scheiber are plotted on Figure 17 along with

two determinations on specimens from our own

collections selected at the ends of our observed

specific gravity range. As has been noted by previous investigators, an essentially straight-line relationship exists between refractive index and

specific gravity for the australites, and indeed for

all tektites (Barnes, 1940). In Figure 17a the line

plotted by Barnes on the basis of data for all

groups of tektites lies slightly above the line proFIGURE 16.—Thin section of flanged australite button from Motpena, South Australia, showing

flow structure and schlieren of differing refractive index.
NUMBER 17

viding the most satisfactory fit with the australite

data, but the difference is small and statistically insignificant.

The data in Figure 17a shows a range in specific

gravity for australites from 2.36 to 2.52, and of

refractive index from 1.493 to 1.529, except for the

aberrant HNa/K group described by Chapman

and Scheiber (1969), which will be discussed in the

next section. The specific gravity range is essentially that indicated by the figures in Table 7,

although a few lower specific gravities have been

recorded from Port Campbell and Pindera. Lower

specific gravities may, of course, be due to bubbles

within the australite glass.

The plot of refractive index against SiO2 percentage (Figure 176) also shows a straight-line reKey to

A "

• --

m =

o =

• =

• =

Chemical Gro

Norma 1

HCa

Hug

HAI

HNa/K

Extreme vaI

study

jping s

es for

(Chapmar

austraI

and Scheiber, 1969):

ites in present

a

2.46 248

SPECIFIC GRAVITY

1.54

1.53

INDEX

ui

 l5 2

•> iCTI'

E

lj 1.51

1.50

1.49

*

• b

\

o

•

o \ •

\

A

\

A ^S .

A

\

A

68 70 72 74

SiO2, WEIGHT PERCENT

FIGURE 17.—Refractive index/specific gravity (a) and refractive index/SiO2 percentage (b) plots for

australites. The broken line in the refractive index-specific gravity plot is that determined by

Barnes (1940) as a mean for all tektites.
36 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

lationship, although the scatter of individual points

is somewhat greater than for the refractive indexspecific gravity plot. This is presumably due largely

to the influence of varying amounts of other components besides SiO2 on the refractive index.

Nevertheless, a measurement of refractive index

(or specific gravity) provides a useful approximation (within about ±1%) of the silica content of

an australite.

CHEMICAL COMPOSITION

A large amount of data on the chemical composition of australites has been published in recent

years, mainly by Taylor (1962), Taylor and Sachs

(1964), and Chapman and Scheiber (1969). On this

account we have limited our analyses to two specimens selected from the extreme values of specific

gravity found in our total collections. These analyses are given in Table 8.

Taylor and Sachs (1964) noted that the percentages of all the major elements except calcium

diminshed as SiO2 percentage increased. Calcium

showed some degree of negative correlation when

graphed, but this was not statistically significant.

Significant negative correlation with SiO2 was also

established for the minor and trace elements Cr,

Li, Ti, Ni, V, Sc, Ba, Rb, and Cs.

One of the aims of this extensive study of australite composition was to establish whether regional differences in composition existed. Earlier

results (Taylor, 1960; Taylor and Sachs, 1961) for

the alkali elements suggested a regional variation

in composition from east to west across Australia.

However, the much larger amount of data assembled by Taylor and Sachs (1964) showed that

autralites of widely different composition exist at

any one locality, as is also apparent from the specific gravity data (Table 7). The specimens analyzed by Taylor and his co-workers were evidently

selected to cover as wide a range of composition

as possible, and this procedure did not take into

account the marked quantization of composition

indicated by the specific gravity data (the significance of which was not apparent when they made

their investigations). The only marked regional

feature of their analyses is the large number of

specimens from Western Australia in the 70%-

72% SiO2 range. Correlating their analytical data

with the specific gravity data, however, one can

TABLE 8.—Chemical analyses of two australites. E. Jarosewich, analyst (C-8 = Pine Dam Area, Lake Torrens; 43-3 =

Lake Eyre South)

Oxide

SiO2

TiO2

M

2°3

Fe2°3

FeO

MnO

MgO

CaO

Na2O

K20

Tota l Fe as FeO

s.g

n

C-8 43-3

77.23

0.61

10.73

0.57

3.68

0.08

1.46

1.61

1.23

2.56

99.76

4.19

2.368

1.495

68.35

0.77

14.19

0.95

4.37

0.09

2.41

4.98

1.46

2.71

100.28

5.23

2.489

1.522

establish two distinct regional populations: (1)

that of Western Australia and the Nullarbor Plain,

with a density peak of 2.45 corresponding to an

SiO2 content of about 71%, and (2) that of Victoria

with a density peak of 2.40 corresponding to an

SiO2 content of about 76%. The Lake TorrensLake Eyre region between Beltana and Cooper

Creek carries a mixture of these two populations.

The specific gravity data for Lake Wilson and

Wingellina specimens, and the single analysis of

a Lake Wilson specimen (Taylor and Sachs, 1964)

suggest that australites from this region, centered

on the South Australia-Western AustraliaNorthern Territory corner, may have a distinctive

composition. Their peak specific gravity is significantly higher than that for any other area, and

Taylor and Sachs commented on the analytical

data for the Lake Wilson specimen as follows:

"[This specimen] is unusual in possessing, in addition to the high value for nickel, the highest
NUMBER 17 37

amounts of Mg, Fe, Co, and Cr. The concentrations of the other elements are normal for the silica

content (69.8 per cent) (1960:250).

Chapman and Scheiber (1969) studied the compositional variations in tektites from the whole

Australasian (Southeast Asia and Australia) strewnfield. They comment: "These data are collected

herein with little attention to geographic distribution pattern but with emphasis on the information

provided as to the chemical nature of the parent

rock from which the tektites derived." With this

in view they selected 530 specimens for chemical

analysis from approximately 47,000 whose specific

gravity they had measured. In their 1969 paper

they report 60 analyses, of which 22 are Australian

specimens. The analyses were classified into a number of chemical groups, and in a later paper

Chapman (1971) provided a map showing the geographical distribution of these chemical groups.

Australite analyses were assigned to the following chemical groups:

Normal: The term "normal" is evidently used in the sense

"very common." The only chemical criteria listed are

CaO>MgO, Na2O>1.25%, and Ni<41 ppm. Practically

all the analysed australites from Western Australia and

the extension of the Nullarbor Plain into South Australia

are in this group, and specimens are also present in collections from eastern South Australia and the adjacent area

of New South Wales.

HCa: H denotes "high"; for the HCa australites CaO

ranges from 1.83% to 5.62%, FeO 3.57%-4.75%, Ni 17

ppm-26 ppm, and Cr 57 ppm-98 ppm. The HCa australites occur only within the low specific gravity "streak"

from Victoria through the Lake Torrens-Lake Eyre region,

but not all HCa australites have low specific gravity;

analysed specimens have specific gravities ranging from

2.361 to 2.501. "HCa" may be something of a misnomer

for this group, since some specimens have lower Ca than

specimens in other group.

HMg: The chemical criteria are MgO>3.4%, Ni>210 ppm,

and Cr>210 ppm. This is a relatively rare type among

australites, only six analyses being recorded. These australites were collected in central Western Australia and

adjacent areas in South Australia and Northern Territory

(Lake Margareta, Serpentine Lakes, Lake Wilson).

HA1: A12O3>14.9%,; found only in N.S.W. (Pindera, Liverpool, and Uralla), except for one specimen in Tasmania.

HNa/K: Nine specimens, all from northwest South Australia, comprise this group; they are characterized by an

exceptionally high Na/K ratio. Na2O/K2O ranges from 2.7

to 3.6, whereas in all other australites and most other

tektites this ratio is always less than unity.

The only chemical group that can be readily

distinguished on the basis of physical properties

(refractive index and specific gravity) is the

HNa/K, and as will be seen from subsequent discussion, the identification of this group as tektites

is questionable. The HCa group shows practically

the full range of refractive index and specific

gravity (Figure 17a), whereas the remaining groups

show a narrower range; however, this restriction

in range may simply reflect the limited composition range of the specimens selected for analysis.

The specific gravity range for the KalgoorlieNullarbor Plain region (where all specimens are

apparently "normal" australites) is 2.385-2.485,

practically the complete range for australites. The

separate character of the HA1 group can be questioned; the three analysed specimens all have low

SiO2 (66.9%-68.5%) and the high A12O3 may simply

reflect the low SiO2, since Taylor and Sachs (1964)

have demonstrated the highly significant negative

correlation of A12O3 with SiO2 for all australite

analyses.

The HNa/K specimens present a perplexing

problem. Chapman and Scheiber found nine

through the specific gravity screening of approximately 47,000 specimens of australites and Southeast Asian tektites; we have found none in a similar

screening of over 1300 australites. Their composition is distinctly different from all other tektites;

Chapman and Scheiber consider them related to

the Ivory Coast tektites, but a glance at their

CaO/MgO plot (Chapman and Scheiber, 1969,

fig. 2) shows that this is hardly tenable, because

Ivory Coast tektites cluster at 1% CaO, 3% MgO,

whereas the HNa/K specimens cluster at 5% CaO,

4% MgO. The

 87Sr/86Sr ratio for the HNa/K

specimens is 0.704 (Compston and Chapman, 1969),

quite different from other australites (0.713-0.718)

and Ivory Coast tektites (0.724). In addition, they

give a fission-track age of approximately 4 million

years (Fleischer et al. 1969). Fleischer et al. conclude

that HNa/K specimens represent a unique tektite fall, preceding that of the Australasian strewnfield, which they place at 0.7 million years ago.

They comment: "To many observers it may seem

odd that a newly identified fall should exist in

the very region where a previously known fall had

occurred."

In view of the remarkable differences between

the HNa/K australites from all other tektites (including the Ivory Coast tektites), the evidence for

their identity as tektites requires careful scrutiny.
38 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

This evidence is somewhat tenuous, resting as it

does on the following statement (Chapman and

Scheiber, 1969:6756-6757):

It might be questioned whether the HNa/K specimens

are really tektites. They were found by three different collectors at four different localities in Australia and were

intermingled in all cases with numerous australites of

ordinary composition. Their shapes include elongates, cores,

and fragments not visually distinguishable from the shapes

of normal tektites with which they were found. Specific

gravity measurements served to cull them from the majority.

A meridianal section from AN245, a typical aerodynamic

core shape (Figure 14a) revealed the same quantitative

distribution of residual tensile and compressive stress as in

normal australite cores. This attests to rapid cooling. Wafers

cut from all but two (AN245 and AN87) of nine analyzed

HNa/K australites exhibit glassy inclusions, both bubbly

and compact, that are indistinguishable from the lechatelierite of normal tektites. All nine show flow structure. Pieces

from three (AN87, AN245, and AN325) were subjected to

our standard test of heating to about 175O°C at low pressure

(—0.1 atm); each melted without frothing or noticeable

vesiculation. They are true tektites.

The illustration (fig. 14a), described as "a typical aerodynamic core shape," could equally well be

described as a rounded pebble; the material appears to be a homogeneous glass, completely

lacking the schlieren so prominent in the accompanying photograph of an australite section. No

mention is made of flange remnants on any of the

specimens, which would clearly identify them as

australites. The chemical composition, as Chapman

and Scheiber point out, is closely similar to that

of a terrestrial andesite, although their Cr and Ni

contents are anomalously high.

So the question arises, if these are not tektites,

what are they? They were all found in northwestern South Australia, six of them from a location

"south of Lake Wilson, 26°20/S, 129°20'E." To our

knowledge no volcanic rocks that might contain

obsidian of the composition of the HNa/K specimens are known in that region. However, the

mountains to the north, the Mann Range, are

high-grade metamorphic rocks of granitic to more

basic compositions, and are extensively veined by

pseudotachylite, evidently formed along zones of

intense shearing. These pseudotachylites are black

and glassy, and pebbles resemble eroded australites.

Chapman and Scheiber comment that the Rb-Sr

data for the HNa/K specimens can be interpreted

as indicating parent material representing very

ancient times of crystallization, of the order of

2500 million years ago, an age consistent with the

Mann Range rocks.

Chemical Composition and the Origin of Tektites

It is ironic that the two scientists who have contributed most to our knowledge of the chemical

composition of australites arrived at diametrically

opposed opinions as to their origin, Taylor ascribing a terrestrial source and Chapman a lunar one.

At the Third International Tektite Symposium

held in Corning, New York, in April 1969, where

much of this chemical evidence was presented, an

informal vote of the conferees revealed an essentially even split between adherents of the lunar and

of the terrestrial origin. The issue was soon to be

decisively resolved. The Apollo 11 moon landing

on 20 July 1969 and subsequent missions brought

back material whose geochemistry almost certainly

negates the possibility of a lunar origin for the

tektites. The evidence has been summarized by

Taylor (1973), as follows:

The Apollo lunar missions provide critical evidence which

refutes the hypothesis of lunar origin of tektites. Tektite

chemistry is totally distinct from that observed in lunar

maria basalts. These possess Cr contents which are two

orders of magnitude higher than tektites, distinctive REE

patterns with large Eu depletions, high Fe and low SiO2

contents, low K/U ratios and many other diagnostic features,

none of which are observed in the chemistry of tektites.

The lunar uplands compositions, as shown by Apollo 14, 15

and 16 samples and the y-ray and XRF orbiter data, are

high-Al, low-SiO2 compositions totally dissimilar to those

of tektites. The composition of lunar rock 12013 shows

typical lunar features and is distinct from that of tektites.

The small amounts of lunar K-rich granitic material found

in the soils have K/Mg and K/Na ratios 10-50 times those

of tektites. The ages of the lunar maria (3.2-3.8 aeons) and

uplands (>4.0 aeons) are an order of magnitude older than

the parent material of the Southeast Asian and Australian

tektites, which yield Rb-Sr isochrons indicating ages on the

order of 100-300 m.y. The lunar lead isotopic compositions

are highly radiogenic whereas tektites have terrestrial Pb

isotopic rations. Lunar §18O values are low (<^7 per mil)

compared with values of +9J6 to +11.5 per mil for tektites.

In summary, a lunar impact origin for tektites is not compatible with the chemistry, age, or isotopic composition of

the lunar samples. A lunar volcanic origin, recently revived

by O'Keefe (1970) encounters most of the same problems.

Recent lunar volcanism (<50 m.y.), if the source of tektites,

should contribute tektite glass to the upper layers of the

regolith. None has been found.

The disproof of a lunar origin for australites reinforces the quest for a terrestrial source of the
NUMBER 17 39

parent material. Taylor and Kaye (1969) demonstrated the close match between the average composition of australites, for both major and trace

elements, and that of greywacke. They therefore

suggested an origin by cometary impact on terrestrial rocks of appropriate composition without

specifying potential source locations. Schmidt

(1962) postulated a meteorite crater in the Wilkes

Land region of Antarctica (approximately 71°S,

140°E) on the basis of striking gravity minima

similar to those observed for Canadian meteorite

craters, and suggested this would be an appropriate

source for the australites. On the other hand Lieske

and Shirer (1964), using a digital computer, calculated the trajectories of tektite-like bodies with

high initial velocities, with a view to determining

whether the debris from an explosive meteorite impact could have attained intercontinental ranges.

They regard it as improbable that the small tektites forming the australite strewnfield could have

been distributed in their present form by a meteorite impact in Antarctica. Taylor (1969) pointed

out that both number and mass of tektites increase

towards the northwest corner of the entire Indoaustralian strewnfield, the largest recorded specimens being of the Muong-Nong type from Laos,

Vietnam, Cambodia, and Thailand; this would

suggest a primary source in the region. Kaysing

(1970) extrapolated from the data of McColl and

Williams (1970) to suggest that Lake Toba in

Sumatra was a possible source area for the Australian group of tektites. Taylor (1970) pointed out

the consensus of opinion that Lake Toba was a

volcano-tectonic depression surrounded by vast

quantities of ignimbrite. Analyses of australites are

dissimilar to Lake Toba ignimbrite, particularly

for the critical elements magnesium, sodium, and

potassium, and also for silica. Taylor considers that

on these grounds there is no a priori case for considering Lake Toba as a potential source area. It

is puzzling that a catastrophic event that sprayed

glass over the southern half of Australia and by

extension to the Philippines and southern China

left no other geological evidences—especially if it

occurred as recently as the stratigraphic age of the

australites (7000-20,000 years BP) would indicate.

Age and Stratigraphical Relationships

It is perhaps misleading to talk about the age

of australites in any general sense. Different procedures devised to "date" australites may in fact

be determining the time of a specific event in a

lengthy history. Some possible events that may be

dated in this context are:

1. The formation of the glass and its cooling

to the argon retention temperature, thereby enabling the determination of a potassium-argon age.

This assumes no subsequent reheating of sufficient

intensity to "reset" the potassium-argon "clock."

Fission-track dating is analogous, in that fission

tracks accumulate in the glass after solidification

and cooling, but may be erased by subsequent reheating.

2. The passage of the australite through the

Earth's atmosphere, presumably dated by age determinations on flange material.

3. The time of incorporation in the geological

formation where the australite is found, dated by

stratigraphy or by radiochemical determinations on

associated material. If the australite is found where

it fell, the age of the enclosing formation presumably gives the time of fall, which should be identical with event 2; transportation may result in the

australite being incorporated in a younger formation, or even apparently in an older formation

(e.g., if washed into a cleft in older rocks).

Potassium-argon dating has been applied to australites by a number of researchers. The most comprehensive data are those of McDougall and

Lovering (1969), which are reproduced in Table 9:

they confirm and extend the earlier work of Reynolds (1960) and Zahringer (1963). McDougall and

Lovering comment:

The apparent K-Ar dates average 0.86 ± 0.06 m.y. (standard

deviation), approximately 0.15 m.y. older than found by

previous workers. The internal consistency of the K-Ar

dates on the australite cores, which have potassium contents

ranging from 1.61 to 2.18 per cent suggests that the dates

are geologically meaningful, and probably record the time

of primary melting. Studies of flanged australites confirm

that potassium is depleted in the flanges relative to the

associated cores, and show that the flanges have considerably

older apparent K-Ar dates than the cores. Because it is

agreed that the flanges were formed by subsequent ablation

of the primary australite cores, it must be concluded that

the flanges contain excess radiogenic argon.

McDougall and Lovering also measured the

K-Ar age of a philippinite and found 0.78 ± 0.05

m.y., slightly higher than the ages of 0.68 to 0.73

m.y. given by Zahringer (1963) for five philippinites. Zahringer found that all the tektites he ana-
40 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

TABLE 9.—Potassium-argon ages of australites (McDougall

and Lovering, 1969)

Locality

Kalgoorlie, WA

Leonora, WA

Musgrave Ranges, SA

Florieton, SA

Charlotte Waters, NT

Myrtle Springs, SA

" composite

Port Campbell, Vic.

Stanhope Bay, Vic.

core

core

core

core

flange

core

flange

core

core

flange

core

flange

flange

core

flange

core

flange

% K

2.05

2.19

1.61

1.79

1.71

1.64

1.71

1.66

1.99

1.92

1.97

1.83

1.90

1.85

1.89

1.81

1.66

1.83

1.82

1.72

Age

0.88

0.79

0.86

0.92

0.87

0.94

0.75

1.05

0.81

0.79

0.91

1.16

0.94

1.79

1.11

0.86

1.12

0.95

0.85

1.09

, m.y.

± 0.03

+ 0.09

± 0.07

± 0.18

± 0.09

+ 0.12

± 0.07

± 0.08

± 0.04

± 0.03

+ 0.09

± 0.04

± 0.21

+ 0.04

± 0.03

± 0.02

± 0.03

± 0.05

± 0.11

+ 0.03

lyzed from different localities in the Indoaustralian

region (Indochina, Thailand, Philippines, Billiton,

Java, Borneo, and Australia gave the same K-Ar

ratio (within experimental uncertainty) and hence

showed the same age.

This apparent consistency in age for tektites

throughout the vast Indoaustralian region has

been cited as important evidence for a common

and contemporaneous origin. Nevertheless, nagging

uncertainties in the interpretation of the K-Ar

ages remain, especially in view of the apparent

older ages for flanges. In this connection, the work

of Clarke et al. (1966) is significant. They point out

that the calculation of the K-Ar ages of tektites

rests on the assumption that all

 40Ar is expelled

from the melt at the time of formation, so that

the measured

 40Ar is entirely the product of the

decay of

 40K since the melting event. To test this

assumption they made glasses of tektite composition from geologically old materials under carefully controlled conditions to promote complete

outgassing. The apparent K-Ar ages of these glasses

were measured, and ranged from zero to over 1 m.y.

They concluded: "The data indicates that the assumption of complete loss of

 40Ar may not be

completely valid, and the interpretation of K-Ar

dating as applied to tektites may need reevaluation."

The results suggest an alternative explanation

of the consistent K-Ar ages of tektites throughout

the Indoaustralian region—that they may not be

true ages, but represent a limit to the outgassing

of preexisting

 40Ar in the source materials. If tektites were formed in a catastrophic impact, as

envisaged by most researchers, then insufficient

time for complete degassing of radiogenic Ar from

the source materials is a distinct possibility. However, this interpretation appears to be negated by

the fission-track ages (Table 10) of Fleischer and

Price (1964), which support the K-Ar ages, although they show a considerable spread. Later

work by Gentner et al. (1969) gives fission-track

ages for australites of 0.11-0.71 m.y., in agreement

with the data of Fleischer and Price.

Fleischer and Price comment as follows:

The nine australites have four distinct and separate

fission track ages which lead to two alternative conclusions

as to the true solidification ages: (1) There were at least four

different solidification events, or (2) track numbers have

been altered over time in such a way as to change at least

three ages from their true values. Although we cannot rigorously decide between these two possibilities, we conclude

that the second alternative is the more reasonable one, the

true age then being 0.70 (±0.04) m.y. There are three reasons

for believing this. First is the very good agreement between

this value and the ages found for australites by Zahringer

(1963) using K-Ar dating. Secondly, we know that simple

thermal conditions can give rise to fading (and hence too

young ages), while conditions for arriving at too large an age

are rare. For samples with as high a uranium content as

tektites the only possibility we know of would be the close

proximity of a deposit of uranium, which would be a neutron source and hence induce fission. Thirdly, in the 0.13

m.y. old Port Campbell australite there were tracks which

showed effects of exposure to elevated temperature. Such

tracks have a somewhat blurry and less crisp appearance

than do unheated tracks, and are easily distinguished from

them. We conclude that the solidification age is 0.70 ± 0.04

m.y., and the other samples were probably heated sufficiently

to produce track fading (one sample recently, two about

0.12 m.y. ago and one about 0.34 m.y. ago).

As noted in Table 10, Fleischer and Price examined some flanged australites from Port Campbell, and found that fission-track densities were
NUMBER 17 41

TABLE 10.—Fission track ages of australites (Fleischer and

Price, 1964) arranged by age (* = flanged specimens; flange

and core gave the same age)

Locality

Kalgoorlie, WA

Port Campbell, Vic

*Port Campbell, Vic

Kalgoorlie, WA

Kalgoorlie, WA

Charlotte Waters, NT

*Port Campbell, Vic

*Port Campbell, Vic

*Port Campbell, Vic

Age, m.y.

<0.03

0.11 ± 0.04

0.13 + 0.02

0.34 + 0.01

0.66 ± 0.01

0.64 + 0.16

0.69 + 0.05

0.69 ± 0.07

0.8 + 0.2

essentially identical in flange and core. They comment:

The track density in the flange, which results from ablation by the atmosphere, should measure the time of entry

into the Earth's atmosphere; the track density in the core

should measure the time of formation of the original tektite,

which reached the Earth's atmosphere as a rigid, cold sphere

(Chapman and Larson, 1963). The total densities found (303

± 22/cm2 for the core and 292 ± 25/cm2 for the flange) in

the three oldest samples are statistically indistinguishable.

Therefore the descent onto Earth must have occurred 0.70

m.y. ago, i.e. much longer ago than the 0.005 m.y. deduced

from geological evidence (Baker, 1960).

These results imply that the formation of the

glass and its passage through the atmosphere were

not separated by a detectable time interval. This

is consistent with evidence of a rapid flight time.

Australites (and other tektites) appear not to have

been exposed to appreciable cosmic-ray irradiation.

Reynolds (1960) has shown that australites do not

contain detectable

 21Ne. From the measured neon

diffusion rate, the measured cross-section for production of neon from other elements, and from

the limit of detectability of

 21Ne Reynolds concluded that the australite he measured had a maximum flight time of 28,000 years. Anders (1960)

did not find any

 26A1 in an australite. The sensitivity of the measurement of

 26A1 (Viste and Anders, 1962) does not, however, preclude a 90,000-

year flight time.

The geological data, however, are completely incompatible with the australites having fallen approximately 700,000 years ago. Experienced field

investigators agree that australites are found in

late Pleistocene or post-Pleistocene formations and

not in older deposits. Fenner (1935), on the basis

of the extensive evidence collected by him, concluded that they fell in early post-Pleistocene times.

Baker (1962), who carefully investigated the australite occurrences near Port Campbell for over thirty

years, and who was also familiar with other localities, wrote as follows: "The evidence from the geological occurrence of australites, supported by

ethnological and pedological evidence, leads to the

conclusion that the age-on-earth of the tektite fall

in Australia is about 5,000 years. It is probably not

under 3,000 years, nor over 6,000 years." Johnson

(1965), discussing specifically the australite occurrence at Lake Wilson, but also drawing on many

years of field experience, wrote: "It appears that

the australites fell soon after the end of the Pleistocene."

Our own observations are in agreement with

these statements. Over most of the vast area we

have prospected, australites are associated with a

readily recognizable geological formation, a wellconsolidated red sand, which is undoubtedly an

aeolian deposit. It contains layers of calcareous

nodules, some of which are moulds of former tree

roots; those layers may represent the B horizons

of ancient soils. This geological formation is generally overlain by unconsolidated red sand, usually

in the form of seif dunes, the sand derived from

the deflation of the underlying formation. Where

stream channels exist, they may have cut down

into this formation some tens of feet, as on Mulgaria Station. The geological evidence suggests that

the red sand formation with which the australites

are associated was deposited under semi-arid conditions—arid enough for extensive wind transportation of the constituent sand, but also humid

enough for the growth of sand-fixing vegetation

and the development of soil horizons. Increasing

aridity apparently brought this depositional period

to a close, and it was succeeded by an extremely

arid period with strong deflation and the development of extensive series of seif dunes. In more recent time the aridity has evidently diminished,
42 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES

since the seif dunes are now essentially fixed by

vegetation. The australites are always near the top

of the consolidated red sand formation, indicating

that they fell shortly before a change to extremely

arid conditions. In South Australia this red sand

formation containing the australite horizon has

been named the Lake Torrens Formation (Williams and Polach, 1971), and its date of deposit

set at about 16,000-20,000 years BP. Lovering et

al. (1972), therefore, concluded that the australite

fall occurred within this time period, although

it may have occurred during the development of

the Motpena paleosol (12,000-16,000 years BP).

During all our field work we have searched for

wood or charcoal associated with australite occurrences, in the expectation of thereby obtaining

carbon-14 dating of the australite fall. This search

has been unsuccessful. For obvious reasons, wood,

even if originally present, is unlikely to survive

in an arid or semi-arid environment. That woody

shrubs were probably present is indicated by the

calcareous moulds of tree roots found in the

australite-bearing formation. Better success has

been obtained in the Port Campbell area as reported by Gill (1965, 1970). A carefully selected

site was excavated using archeological methods, in

which the sandy soil was removed inch by inch.

Fourteen australite specimens were discovered in

situ, at depths of 11 to 14 inches, along with materials for radiocarbon dating. All the australites

were found on or up to three inches above a hardpan layer. Seven radiocarbon datings were made of

fossil hardpan material, of charcoal at various

levels above the hardpan, and of grass tree resin

in situ above the hardpan. The oldest date was

7,300 years for carbonized wood fragments in the

hardpan. Gill concludes that australites fell prior

to the comparatively arid postglacial thermal maximum, which began about 6500 years ago; this is

consistent with our deductions from the stratigraphic relations at interior sites.

We are thus faced with what seem to be irreconcilable "facts" regarding the time of fall of australites. Geological evidence shows the fall of

australites took place some time during the period

7000-20,000 years BP, whereas K-Ar and fissiontrack figures show the age of formation to be approximately 700,000-860,000 years BP. There seem

to be three possibilities: (1) the figures are wrong,

(2) the geology is wrong, or (3) something else is

wrong.

It is probably presumptuous to suggest that the

700,000-860,000-year figure is "wrong." It is the

result obtained by several independent and experienced investigators, and its significance is apparently strengthened by the fact that tektites

throughout the Indoaustralian region, from the

Philippines through Indochina, Thailand, and

Indonesia to Australia all give this same potassiumargon age. However, it may be permissible to suggest that the interpretation of this figure may be

wrong, i.e., that it does not measure the time of

solidification of the glass. We do not know what

material was melted to form the tektite glass, but

it is conceivable that this material contained argon

which was not completely expelled during the melting process. Inherited argon would thereby give

a spurious and too great age for the time of formation of the glass. On this interpretation the uniformity of tektite age throughout the Indoaustralian

region—the youngest age measured for any tektites

—may not strengthen the argument of consanguinity, but may instead reflect the limit for argon

degassing under conditions of formation of tektite

glass. The fact that K-Ar dating for the flange and

core of australites has given a greater age for the

flange than the core adds to the uncertainty of

the K-Ar dating of these objects.

However, this interpretation of the potassiumargon age appears to be vitiated by the fission-track

investigation, which supports the 700,000 year age,

and, in addition, shows that flange and core have

identical fission-track density. This would seem

to demonstrate that the australite glass was formed

about 700,000 years ago, and that the australites

descended through the Earth's atmosphere shortly

thereafter.

On the basis of these arguments, therefore, it

has been suggested that the geology is wrong. As

Schaeffer (1966) states the case: "The geological age

does not measure the arrival of these tektites on the

Earth as the tektites are detrital to the deposits and

were originally deposited in other older formations." While this is certainly true for many, if

not most, of the tektite occurrences in other parts

of the world, a large number of australite occurrences are certainly not of detrital origin. No one

who has seen the Port Campbell localities and examined the many perfectly preserved australites

therefrom is likely to argue that these specimens
NUMBER 17 43

are not being found essentially where they fell.

The complete lack of solution etching, even on

thin plates weighing as little as 0.03 gram, is a

powerful argument against the australites having

been subjected to terrestrial weathering, even in

situ, for more than a few thousand years. Our own

experience in the arid interior indicates that at

many locations we were collecting australites essentially where they fell. Delicate surface markings

and flanges, which would certainly have been destroyed in a few years exposure to present surface

conditions, let alone transportation, are still present on many of the specimens. Their distribution

is completely unrelated to stream channels; they

are often found on higher ground which is being

actively deflated; no detrital material in the same

size range, such as stream pebbles, is present. As

Lovering et al. (1972) commented, if the australites

fell 700,000 years ago they would not be found in

the Lake Torrens region, since this area has been

aggrading throughout the Pleistocene, and a

700,000-year horizon would be deeply buried.

Having reached an apparently irreconcilable

impasse between the physical dating and the geographical dating of the australite fall, one can

only turn to the third proposition—something else

is wrong. Perhaps this can better be stated as

something—some unsuspected factor—has been

overlooked. We have no plausible suggestions for

this unsuspected factor or factors. It may not be

inappropriate, however, to recall other conflicts

of this kind, such as that between Lord Kelvin and

many geologists as to the age of the Earth, before

the discovery of radioactivity completely altered

the situation.
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