Date electronic copy
received at AINSE:
13 October 2010
PROGRESS REPORT FOR AINGRA09031
PROJECT TITLE
Refining shell mound chronologies on the Sandalwood River,
Mornington Island
INVESTIGATOR(S)
Institution and Department
Chief Investigator
Dr Sean Ulm
Aboriginal and Torres Strait Islander Studies, The University of
Queensland
Other Investigators
Geraldine Jacobsen (ANSTO)
Daniel Rosendahl (University of Queensland)
Students
Daniel Rosendahl (University of Queensland)
ANSTO Investigators
Geraldine Jacobsen
Specialist Committee
A
SCIENTIFIC OBJECTIVES
This project builds on ARC-funded studies to refine shell mound chronologies on the Sandalwood River, Mornington
Island. Although shell mounds are a common feature of the coastal archaeological record of northern Australia,
after four decades of study our understanding of mound formation, use and abandonment remains rudimentary.
Small numbers of dated mounds spread over large geographical areas without known local palaeoenvironmental
and taphonomic contexts hamper more sophisticated approaches. This project addresses these issues through the
dating of a series of shell mounds within a well-studied environmental context.
PROGRESS REPORT and RESEARCH OUTCOMES
Termination dates were obtained on four Aboriginal shell mounds located on the saltflats surrounding the
Sandalwood River on the central north coast of Mornington Island (Appendix A, Figure 1). Samples of the
suspension-feeding bivalve Anadara granosa were collected from the surface of shell mounds that have been
recorded previously, but not dated. Combined with previous studies, dates are now available for 12 of the 35 shell
mounds documented in the area. In addition, many natural shell deposits have been identified around the periphery
of the Sandalwood River saltflats, dominated by the large black-lipped oyster (Striostrea mytiloides), with specimens
frequently weighing over 500g with valve heights in excess of 25cm. Seven samples of black-lipped oyster from the
surface of these deposits have now been dated.
The dates obtained on natural deposits span from 3938-6459 years ago (clustering between 5200 and 6500 years
ago) during a period when sea-levels were slightly higher than they are today (up to 2m) (Figure 1). Sea-levels
dropped down to present levels after 5300 years ago (Reeves et al. 2008). The position of the dated natural
deposits towards the margins of the saltpan is consistent with a growth position for these shell assemblages at a
time when these areas were more regularly inundated (i.e. they were in the intertidal zone). These areas are now
hypersaline flats only inundated during king tides, storm surges and wet season rains. Significantly, there is a clear
chronological gap (of c.1200 years) between the natural shell deposits and the initiation of cultural shell deposition
(Figure 1).
The geomorphological and archaeological records of the Sandalwood River area show that in the mid-Holocene the
area experienced major landscape change associated with changing sea-levels and sedimentation regimes,
reflected in the in situ death assemblages of black-lipped oysters stranded above regular innundation levels. The
first archaeological evidence for human use of the area dates to shortly before 2100 years ago, with mound
construction extending into the very recent past.
These preliminary results are at odds with conventional understandings of shell mounds in northern Australia. It has
been suggested that shell mound formation ceased across northern Australia at 600-800 BP (Hiscock and Faulkner
2006) whereas the Sandalwood mounds appear to have been occupied from before 2000 years ago to the present.
Second, the Sandalwood mounds do not occur in clusters. Many mounds across northern Australia occur as part of
groups and it is assumed that they were occupied simultaneously and are associated with patterns of reduced
residential mobility (sedentism) (Hiscock 2001).
Figure 1. Calibrated radiocarbon ages for shell deposits on the the Sandlewood River saltpan from both cultural
(yellow) and natural (red) deposits (n=25) arranged in order of increasing age. Error bars show the 95.4%
calibrated age-range. Note the apparent gap (green) between 2710-3938 years ago. Calibrations were calculated
using OxCal 4.1 (Bronk Ramsey 2009) and the marine calibration dataset of Reimer et al. (2009). A ∆R value of –
49±102 was applied (Ulm 2010). Laboratory numbers are shown for the four ages obtained under AINGRA09031.
References
Bronk Ramsey, C. 2009 Bayesian analysis of radiocarbon dates. Radiocarbon 51(1):337-360.
Hiscock, P. 2001 Late Australian. In Encyclopedia of Prehistory, pp.132-149. New York: Plenum Press.
Hiscock, P. and P. Faulkner 2006 Dating the dreaming? Creation of myths and rituals for mounds along the
northern Australian coastline. Cambridge Archaeological Journal 16:209-22.
Reeves, J.M., A.R. Chivas, A. Garcia, S. Holt, M.J.J. Couapel, B.G. Jones, D.I. Cendon and D. Fink 2008 The
sedimentary record of palaeoenvironments and sea-level change in the Gulf of Carpentaria, Australia, through the
last glacial cycle. Quaternary International 183:3-22.
Reimer, P., M. Baillie, E. Bard, A. Bayliss, J. Beck, P. Blackwell, C. Bronk-Ramsey, C. Buck, G. Burr, R. Edwards,
M. Friedrich, P. Grootes, T. Guilderson, I. Hajdas, T. Heaton, A. Hogg, K. Hughen, K. Kaiser, B. Kromer, F.
McCormac, S. Manning, R. Reimer, D. Richards, J. Southon, S. Talamo, C. Turney, J. van der Plicht and C.
Weyhenmeyer 2009 Intcal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP.
Radiocarbon 51(4):1111-1150.
Ulm, S. 2010 Progress report for AINGRA09025. Retrieved 11 October 2010 from
http://www.ainse.edu.au/ainse/for_academic_researchers/awards_progress_reports/2009_progress_reports.html.
DATA
Final AMS summary results and sample details are presented in Appendix A. Calibrations undertaken using OxCal
v.4.1 (Bronk Ramsey 2009) and the IntCal09 and Marine09 calibration datasets (Reimer et al. 2009). For marine
samples a ∆R of −49±102 as recommended by Ulm (2010) is employed.
Appendix A. Summary results of AMS dating.
Site
Sq
XU
Site 43
Site 47
Site 50
Site 83
–
–
–
–
–
–
–
–
Depth
(cm)
surface
surface
surface
surface
Sample
Anadara antiquata
Anadara antiquata
Anadara antiquata
Anadara antiquata
* Date may extend out of range (i.e. modern).
$ ∆R of −49±102 as recommended by Ulm (2010).
Weight
(g)
Lab. No.
∆13C
OZL-931
OZL-932
OZL-933
OZL-934
-2.9±0.1
-0.6±0.1
-2.2±0.1
-1.9±0.2
F14C
%
95.33±0.44
91.39±0.51
95.55±0.34
95.23±0.37
CRA
∆R$
385±40
725±45
365±30
395±35
−49±102
−49±102
−49±102
−49±102
Calibrated Age
BP (95.4%)¥
0*-270
146-610
0*-256
0*-273
Calibrated Age BP
Median
112
398
102
115
Signature of Investigator preparing the report for
After signing this report please fax this page with your signature for our files
Proj: AINGRA09031
Date:
13 October 2010
PUBLICATIONS / REPORTS arising as a result of your work.
Rosendahl, D., S. Ulm, G. Jacobsen and P. Memmott 2010 Insular Ideas: An Archaeology of Isolation in the
Wellesley Islands? Paper presented to the Australian Archaeological Association Annual Conference, Batemans
Bay, NSW, 10-13 December.
PhD STUDENTS
Student Name
Daniel
Rosendahl
Thesis Title
The Way it Changes: The Archaeology of the
Sandalwood River
* Anticipated conferment date only.
Degree
PhD
Conferment Date
2011*