Jones, R & Polach, H.A. 1975. ANU Radiocarbon Dating

Australian Archaeology

Archived at Flinders University: dspace.flinders.edu.au

Full Citation Details:

Jones, R & Polach, H.A. 1975. ANU Radiocarbon Dating

Laboratory, General Projects. 'Australian Archaeology', no.2, 56-61.

Thorne, having submitted h i s Ph.D. t h e s i s t o t h e University of Sydney on h i s Kow Swamp and Lake Mungo human material, spent t h e year tidying up odd ends and t h i n k i n g f u r t h e r about t h e implications of t h e Australian hominid material t o t h e broader question o f t h e emergence of modern s @ e m man. He v i s i t e d new s i t e s i n western New South Wales, and continued working with A . C a r s t a i r s on a bibliography of Australian Aboriginal palaeopathology. The West Point Tasmanian cremated human material, o r i g i n a l l y excavated i n 1965 by Jones, and analysed i n 1967 by Thorne, was s e n t t o i t s f i n a l r e s t i n g place i n t h e Tasmanian Museum and A r t Gallery, having been photographed and catalogued by Markovic and Carstairs.

Rhys Jones (with h e l p from department a1 members)

ANU RADIOCARBON DATING LABORATORY GENERAL PROJECTS

The laboratory is playing an important r o l e i n a number of research p r o j e c t s . Indeed, t h e r e i s a continuing and

increasing need f o r laboratory generated research involving improvements i n d a t i n g techniques, a n a l y s i s , i n t e r p r e t a t i o n and reporting of r e s u l t s ; parameters fundamental t o t h e v a l i d i t y of dating such as environmental contamination and s e l e c t i o n of applicable dating standards. Equally important is p a r t i c i p a t i o n on a cooperative b a s i s i n research generated by other departments and i n s t i t u t i o n s , o f t e n involving f i e l d work.

Low-level Liquid S c i n t i l l a t i o n Counting Parameters (H.A. Polach, G.E. Calf, I . Fraser, J . D . Gower)

Comaercially available l i q u i d s c i n t i l l a t i o n counting equipment i s capable of e s t a b l i s h i n g n a t u r a l

cl4

concentrations within t h e age range of ca. 1000 t o 25,000 years before p r e s e n t (BP). We have shown t h a t s i g n i f i c a n t improvements a r e p o s s i b l e i f modification t o equipment a r e c a r r i e d out involving operations a t reduced high voltage associated with masking of t h e photo- m u l t i p l i e r tubes, and c a r e f u l s e l e c t ion of o t h e r o p e r a t i n g parameters such a s gain and % e f f i c i e n c y s e t t i n g s .

Improved g l a s s counting v i a l design ( t o reduce background) and sample carbon t o benzene ( t h e l i q u i d s c i n t i l l a t i o n counting medium) synthesis together with b e t t e r p u r i f i c a t i o n procedures have i n our case led t o increased p r e c i s i o n of cl4 a c t i v i t y

measurements within the range of 100 to 42,000 BP. The use of "Teflon" (poly-tetra-f luroethylene) counting vials further reduces the background count significantly

.

When these vial S

are used with an optimised liquid scintillation spectrometer and most pure benzene is counted, the relative factor of merit equals the best gas-proportional cl4 detection equipment and procedures. Potentially such application would extend our dating range from lk~ntemporary~~ to ca. 50,000 years BP. The precision of age determinations becomes such that limitations are no longer imposed by detection and measurement of residual

cl4

activity of the sample, but by other parameters such as sample size, sample chemistry, post depositional contamination and collection techniques

.

Computerisation of Data Handling and Age Reporting

(H.A. Polach, M.W. Ray, Anne Sandilands)

In 1967 we established our first data handling computer programmes. These were basically output data statistical

analysis (CSIRO) and age calculations (ANU)

.

Over the years improved and extended versions of these have been written.

However, modification and updating of both CO uter Centre facilities and an ever increasing demand for

34

^age

determinations necessitated a systems analysis. This showed that our first need (both for efficiency and economy) was to handle all our data analysis at the ANU Computer Centre. Our second immediate need was to establish a computerised primary data storage and retrieval system together with statistical date analysis, short term equipment performance analysis and a preliminary age calculation programme. Thirdly, there is need to establish data sorting programmes to enable monitoring of the long term equipment stability and reproducibility and based on these, to produce a final age report. Fourthly, lfon-linell data handling should be evaluated.

The first two steps have now been completed. This we11 documented (but as yet unpublished) programme has already been requested by five radiocarbon dating laboratories throughout the world. To complete the third and fourth stages of programme development, a programmer has been appointed to work with us for six months next year.

Select ion of Modern Reference Standards (H.A. Polach)

Two problems have been recognised. One is to provide a readily available and reproducible radiocarbon dating standard for all dating laboratories. The other concerns divergencies of

c l 4

activity from this reference standard of modern samples in different environments.

The study correlating the activity of the ANU Sucrose secondary

cl4

dating standard (introduced in 1972) to that of the NBS Oxalic Acid primary dating standard has almost been completed. International cooperation has been excellent and almost all the laboratories invited by us to participate in this cross checking programme have supplied preliminary or final

dating standard w i l l have i t s desired e f f e c t i n bringing a l l C' concentrations (ages) reported r e l a t i v e t o t h e primary standard i n t o l i n e . Indications a r e t h a t t h e i n t e r - laboratory v a r i a t i o n of +2%, associated with usage of NBS Oxalic, w i l l be reduced t o l e s s than +0.5%.

The problem of assigning absolute

cl4

ages t o any sample, using t h e radiocarbon d a t i n g standard, stems from t h e now wide1 recognised v a r i a t i o n s of

cl4

concentrations i n nature. Cr4 l e v e l s i n many environments

-

notably t h e ocean

-

d i f f e r from l o c a l o r global atmospheric means, n e c e s s i t a t i n g t h e establishment of local standards f o r p a r t i c u l a r s i t e s and sample types. Many of t h e p r o j e c t s i n which w e a r e involved require t h i s fundamental referencing and we continue t o provide t h i s basic research.

The Greater Barrier Reef Geochronology and Geomorphology

(D. Hopley, R.F. McLean, H.A. Polach, T. Scoffin, D.R. Stoddart, B.G. Thorn)

Three main dating programmes a r e r e l a t e d t o t h e Royal Society Coral Reef Exploration p r o j e c t . Drill cores, s u r f i c i a l reef geology and selection of modern reference standards.

Drill Cores : The Pleistocene-Holocene boundary was recognised i n t h e Bewick Island core. Five C' age determinations have been completed and no f u r t h e r d a t i n g of t h i s c o r e i s expected.

Three f u r t h e r samples from t h e Stapleton Island c o r e have y e t t o be dated.

S u r f i c i a l r e e f geology: The r e e f i s l a n d s comprise a complex s e t of geomorphological u n i t s , from which a1 l s u r f i c i a l samples dated a s Holocene i n age. Our concern is t o e s t a b l i s h t h e chronology of rapid c hanges i n i s l a n d s t m c t u r e , t h e i r

evolutionary p a t t e r n and r e l a t i o n t o s e a l e v e l changes. R e s u l t s i n d i c a t e t h a t t h e s e a reached approximately i t s present l e v e l by 6000 years BP.

Modern reference standards : Some seventeen samples of l i v i n g coral and marine p l a n t s were c o l l e c t e d t o e v a l u a t e

cl4

concentration v a r i a t i o n s i n t h i s oceanic environment. When completed, t h i s study w i l l allow t h e proper r e l a t i o n s h i p between t h e primary (and secondary) radiocarbon d a t i n g standards and reef material t o be established.

Quaternary Sea Level Changes

(J. Chappell, P.J. Cook, M . J . Head, T. Langford-Smith, H.A. Polach, B.G. Thom, C. von d e r Borch)

Conflicting radiometric d a t a ( c l 4 and T ~ ~ ~ from ~ / u ~ ~ ~ ) Quaternary shorelines have been d i f f i c u l t t o reconcile. W e have

demonstrated t h a t some of t h e e r r o r s a r e due t o i n d i s c r i m i n a t e sample c o l l e c t i o n and o t h e r e r r o r s a r e due t o post d e p o s i t i o n a l changes (contamination) i n t h e samples.

In corals and shells contamination by infill and by boring during early diagenesis is followed by progressive recrystallisation, with accompanying sa le to environment chemical exchange. Cross-checking of CIPe and Th230/~234 of samples from excellent exposure indicates that cl4 dating of corals becomes increasingly unreliable beyond 20,000 years BP, while within the Holocene Period cl4 chronologies for corals appear more consistent than Th230/~234. Discrepancies between the methods for Recent corals warrant further investigations.

cl4

dating of coastal feature by incorporated fossil wood, peat and other organic matter produces two other sources of error: misassociation of sample and event (largely a field problem) and post-depositional contamination of samples by

organic matter of different origin and age (largely a laboratory problem). In addition to selected field consultations, we continue to chemically and physically fractionate samples where contamination is suspected. This enables us to evaluate the total site history.

PUBLICATIONS

A1 len

,

Jim 'The excavation of Archaeological Sites

' .

1974 In The Resource A t l a s o f Papua N e w Guinea (ed

.

Edgar Ford) Jacaranda Press.

A1 len, Jim 'Caving and Archaeology in Papua New Guinea1.

1974 Nuigini Caver, Vo1.2, No.4, 235-6 (November 1974).

Allen, J., and Littlewood, H. 'Funerary cave pottery from 1974 the Cape Rodney area, Central Papual. Records

of t h e P a p a Nm Guinea Public Musewn and A r t GaZZeqj, 4, 1-20.

Bowdler, S. 'An account of an archaeological reconnaissance 1974 of Hunter1s Isles, North-west Tasmania, 1973/4'.

Records o f the Queen V i c t o r i a Museum, lkzunceston, 54.

Calf, G.E. and Polach, H.A. 'Teflon vials for liquid scintillation 1974 counting of carbon-14 samples1. In Liquid

s c i n t i ZZation counting: Recent deve Z o p e n t s (eds. P.E. Stanley and B.A. Scoggins), 223-34.

New York: Academic Press.

Fraser, I., Polach, H.A., Temple, R.B. and Gillespie, R.

1974 'Purity of benzene synthesised for liquid scintillation C-14 dating1. In Liquid s & n t i l Zation counting: Recent developments

(eds. P.E. Stanley and B.A. Scoggins), 173-82.

New York : Academic Press.

Golson, J. 'Charles Andrew Sharp (1906-1974)

.

^232e

1974 J m Z of P&fic History, 9, 131-33.

Hughes, P.J. Sullivan, M.E. and Lampert, R.J. 'The use of 1973 silcrete by Aborigines in southern coastal

N.S.W.'. Archaeobgy and Physical AnthmpoZogy in Oceada, 8, 220-25.

Hughes, P.J. and Sullivan, M.E. 'The re-deposition of midden 1974 material by storm waves

'.

^{JoumaZ of the}

Pru>ceed$ngs of the Royal Society of N.S.W., 107, 6-10.

Hope, J. 'The biogeography of the mammals of the 1974 Bass Strait islands'. In Biogeogmphy mzd

EcoZogy in Tmmunia (ed. W.D. Williams), 321-39. The Hague: W. Junk N.V.

Hope, J., Brown, G. and McIntosh, B.S. 'Natural History of

Irwin, G.

1973

Irwin, G.

1974

Lampert, R.J.

1973

Lauer, P.K.

1974

OtConnell, J.F.

1974

OIConnell, J.F.

1974

the Hogan Group. I. Physical environment

and vertebrate fauna'. Papers of the proceedings of the RoyaZ Society of T a d a , 107, 65-72.

'Man-land relationships in Melanesia: an investigation of prehistoric settlement in the islands of the Bougainville Strait

' .

Archaeology and PhysicaZ AnthmpoZogy in Oce~tzk, 8, 226-52.

'Review of Pacific Anthropological Records Nos. 6,7,8,9,14,15,16 and 17'. ArchaeoZogy and PhysiazZ A n t h m p o b g y in Oceania, 9, 85-6.

'Australia before the white mant. In Austmtia and Wtaitt in the Nineteenth Centmy. (ed. J.S. Hagan), 1-27.

Hawthorn : Longman.

'Pottery traditions in the DtEntrecasteaux Islands of Papua'. OccasionuZ Papers in Anthrr,poZogy, 3. St Lucia: University of Queensland, xv+267pp.

'Spoons, Knives and Scrapers: the function of Yilugwa in Central Austral iav

.

^Mankind,

9, 189-94.

Review of Patterns of Indian Burning in California: Ecology and Ethnohistory, by H.T. Lewis. JowruzZ of Cazifornia

AnthropoZogy, 1, 118-20.

OIConnell, J.F. 'Perris Reservoir Archaeology: Late 1974 Prehistoric Demographic Change in south-

eastern California'

.

Archaeological Report No 14, State of California, Department of Parks and Recreation. (Ed. with P. Wilkie,

T.

King and C. Mix)

.

Specht

,

^J

.

'Stone Pestles on Buka Island, Papua New Guineat. Mcmkind, 9, 324-8.

Ward, G. ' A Paradigm for Sourcing New Zealand Archaeological Obsidians

.

^{JoumaZ of the}

Royal Society of NW Zealand, Vo1.4, No. l, 47-62.

Compiled by R. Jones, H.A. Polach,

Department of Prehistory

Research School of Pacific Studies, Australian National University