A large area archaeological excavation at Cuddie Springs. (News & Notes).

A large area archaeological excavation at Cuddie Springs. (News & Notes). Key-words: megafauna meg��a��fau��na?n. (used with a sing. or pl. verb)Large or relatively large animals, as of a particular region or period, considered as a group.meg , Cuddle Springs, stone artefacts,environmental change There are three problematic but connected processes during the last100,000 years of Australian prehistory. These are: the date of initialhuman settlement; understanding the period of climatic flux culminatingin the Last Glacial Maximum The Last Glacial Maximum (LGM) refers to the time of maximum extent of the ice sheets during the last glaciation (the W��rm or Wisconsin glaciation), approximately 20,000 years ago. This extreme persisted for several thousand years. around 18-22,000 years ago; and explainingthe extinction of the megafauna. The timing of human arrival andpopulation expansion rates are not well understood though mostenvironments were occupied by about 30,000 BP (Mulvaney & Kamminga1999: 172-89). While the broad framework of climatic change during theLate Pleistocene has been established, localized environmentalconditions are more difficult to resolve, particularly in the arid zone.The megafaunal extinctions were a global phenomenon and explanatorymodels, at least for North America and Australia, depend in differentways on the role of people and climate change (Martin & Klein 1984;Flannery 1994; Choquenot & Bowman 1998; Horton 2000; Head 2000; Wroe& Field 2001). If we accept recently reported ages of selected megafaunallocalities in Australia and West Papua (Roberts et al. 2001) andluminescence dates for a human burial in Australia's southeast(Thorne et al. 1999), then a temporal overlap could be as much as 50,000years or as little as 10,000 years. Either way it is hard to continue toargue for humans as the primary agent in the extinction process,especially if, as argued by Flannery (1994), human hunters dispatchedthe megafauna within a short time after their arrival. On the otherhand, widely accepted dates for initial human arrival in Australia arefrom 40-45,000 years and a case could be made that most megafaunalextinctions had already occurred (O'Connell & Allen 1998). InTasmania, megafauna appear to have become extinct prior to the arrivalof people (see Cosgrove & Allen 2001). Ecological data suggest morecomplex processes at work, whether or not humans are directlyimplicated. For example, browsers dominate the extinct faunal assemblagein Australia; those that survived underwent phyletic phy��let��ic?adj.Of or relating to the evolutionary descent and development of a species or group of organisms; phylogenetic.[From Greek ph dwarfing andconditions improved for grazers. Furthermore, the same restricted rangeof species are consistently represented in Late Pleistocene sites.Moreover, it is not clear precisely when, where or how rapidly anyparticular species became extinct (e.g. Miller et al., 1999; Field &Boles, 1998). Wright (1986) predicted that megafaunal extinctionsprobably represented a mosaic of events across the continent and as suchthe evidence needs to be evaluated on a site-by-site basis. It is rare to find megafaunal bones in association with artefactsanywhere in Australia, and Cuddie Springs is the only known site on theAustralian continent where such a stratified stratified/strat��i��fied/ (strat��i-fid) formed or arranged in layers. strat��i��fiedadj.Arranged in the form of layers or strata. record can be found. Theaim of this paper is to summarize the results of the 1997 excavations,that provide new data on site structure, and support the broadstratigraphic sequence described in earlier work. Cuddie Springs is an ephemeral lake in the semi-arid southeast.Flaked stone artefacts are found in direct physical association with arange of megafauna that includes Genyornis newtoni, Diprotodon sp. andSthenurus sp. in a stratified deposit of lacustrine la��cus��trine?adj.1. Of or relating to lakes.2. Living or growing in or along the edges of lakes.[French or Italian lacustre (from Latin lacus, lake) + clays, dated tobetween ~36,000 and 27,000 years ago (Field & Dodson 1999; Fifieldet al. in press; TABLE 1). An environmental record spanning the periodof human/megafauna overlap provides a picture of local and regionalconditions through time (Field et al. in press). The human/megafauna association at Cuddle Springs is in a sealedunit between ~1 m and ~1.7 m depth (FIGURE 1). The upper limit, at ~1 mdepth, is defined by a deflation pavement probably formed over a10,000-year period (Field et al. in press). It consists almost entirelyof flaked stone artefacts (~50,000 artefacts/cu. m) and is less than 5cm in depth. The lower limit, at ~1.7 m depth, is a second old landsurface described as a beach lag deposit that caps a band of concretedferruginized sands. Within this horizon are two identifiablestratigraphic units representing different environmental phases (Field& Dodson 1999). The assemblages associated with each stratigraphicunit are distinctly different from each other and megafauna are presentin both horizons (Furby 1995). [FIGURE 1 OMITTED] The association of bones and stones implies contemporaneity ofpeople and animals, and this is supported by recent dating studiesindicating that there are no older sediments in the horizons which wouldsuggest intrusion of material from elsewhere (Roberts et al. 2001).Direct dating of the bones by Amino Acid Racemisation (AAR) or the AMS AMS - Andrew Message System radiocarbon technique (Clarke 1999; Field & White, unpublishedresults) have been unsuccessful and electron spin resonance electron spin resonance (ESR)or electron paramagnetic resonance (EPR)Technique of spectroscopic analysis (see spectroscopy) used to identify paramagnetic substances (see (ESR ESR - Eric S. Raymond )studies are pending. Establishing a link between the people and animalsis also difficult. Surface modifications from butchering, in the form ofcutmarks or breakage patterns, can be absent on bones of large animals(Pickering 1995) and there are few cutmarks on any bones at CuddieSprings. For this reason usewear and residue studies are important inidentifying tasks associated with artefact use and site functions.Spatial patterning and site structure are important aspects ofreconstructing site activities. The sheer size of the fauna means alarge area excavation is imperative. At Cuddle Springs, a 15x15-m area was opened down to the deflationpavement, dated by radiocarbon and OSL OSL Open Source LabOSL Office of Student LifeOSL Open Source LicenseOSL Oregon State LibraryOSL Order of St Luke the PhysicianOSL Optical Stimulated LuminescenceOSL Oud Strijders Legioen (Dutch)OSL Order of Saint Luke to around 28,000 years (FIGURES 2& 3, TABLE 1). A 15x15-m excavation is a minimum requirement ifissues such as site structure and patterning of hunter-gatherer campsare to be investigated, as has been documented in ethnographic studiesfor the Central Australian arid zone (e.g. Spurling & Hayden 1984;O'Connell 1987; Nicholson & Cane 1991). Investigations of sitefunction at Cuddle Springs have previously been limited by the smalltrench size (~2x2 m). [FIGURES 2-3 OMITTED] The 1997 excavations aimed at establishing the nature of theoverburden which is thought to be disturbed, assessing the spatialcontinuity of the Pleistocene archaeological deposits, and to sample theearliest archaeological levels for further evidence of cultural materialin association with megafaunal elements. The initial findings of thefield season include: i Conclusive evidence for disturbance of the overburden with thediscovery of a number of cow skeletons lying on top of the deflationpavement. Radiocarbon dates show age inversions in the sediment directlyoverlying overlyingsuffocation of piglets by the sow. The piglets may be weak from illness or malnutrition, the sow may be clumsy or ill, the pen may be inadequate in size or poorly designed so that piglets cannot escape. the deflation surface (TABLE 1) and the undifferentiated claysof the upper i m are in contrast to the stratified sediments below thedeflation pavement. Glass flakes and historic material (including nailsand wire) have also been recovered from the overburden. No modernmaterial has been recovered from within or below the deflation surface. The cow bones in the overburden represent individuals found indiscrete locations. The bones were not all lying flat but in differentorientations (FIGURE 4), consistent with trampling by large herbivores(see Haynes 1985: 61). Anderson & Fletcher (1934) found the remainsof bullocks and horses in the upper sediments during Australian Museumexcavations in 1933, but there were few contextual details reported. Theorientation of the cow bones from the 1997 excavations is not dissimilarto those of the megafauna lying on the old land surface at ~1.7 m depth,suggesting that the depositional processes in train at Cuddie Springshave not changed significantly for many millennia. [FIGURE 4 OMITTED] ii Establishing the spatial extent of the Pleistocene deflationpavement at approximately 1 m depth. The deflation pavement was found tobe continuous across the 15x15-m area, and in a series of backhoeexcavated pits (~1x2 m) away from the main trench (see FIGURE 3). FIGURE5 shows the deflation pavement surface as exposed in the excavation. Atrench excavated between the well fence and the well proper has revealedthat the pavement was intact across this area. The pavement appears tocover an estimated area of approximately 100 m in diameter; and, withinthe main trench, shows no evidence of disturbance (such as may occurwith cracking or swelling clays); and forms a continuous capping to thePleistocene deposits. [FIGURE 5 OMITTED] iii Establishing the spatial continuity of the archaeologicaldeposits (Archaeological Levels 2,3 and 4). A series of 1x1-m pits wereexcavated to investigate the nature of the sub-deflation pavementdeposits. Archaeological finds were recovered from each square inconcentrations and composition consistent with the assemblages from thepreviously reported excavated squares F10 and G10 (Field & Dodson1999). iv At the base of the archaeology (AL) complete elements ofGenyornis and flaked stone were recovered. The earliest archaeologicallevels in square F10 were excavated to the surface of the beach lagdeposit. The assemblages recovered from these levels were consistentwith material excavated previously from AL1, i.e. the complete lowerlimb bones of Genyornis, and also included macropod macropodmembers of the family Macropodidae; includes kangaroo, wallaby. and wombat wombat,shy marsupial of Australia and Tasmania, related to the koala. The wombat is a thick-set animal with a large head, short legs (giving it a shuffling gait), and a very short tail. It is about 3 ft (91.5 cm) long. mandiblesas well as flaked stone representing early manufacturing stages. v Identifying the location of the 1933 Australian Museum trenches.Two of the 1933 excavation trenches were located when the deflationpavement was exposed (see FIGURE 2). These tally with a hand-drawn mapof the claypan In geology, a claypan is a dense, compact, slowly permeable layer in the subsoil having a much higher clay content than the overlying material, from which it is separated by a sharply defined boundary. Claypans are usually hard when dry, and plastic and sticky when wet. excavations by the Australian Museum palaeontologist C.S.Anderson (Anderson & Fletcher 1934). The clean breaks in the surfaceof the deflation pavement indicate it was sub-surface at the time of the1933 excavations. The wall sections exposed in 1997, adjacent to thesepits, clearly show where slumping has occurred confirming reports thatthe pits were not backfilled following the 1933 excavations. vi The discovery of an historic well. The well was located over thecentre of the depression delineated by the deflation pavement. Itappears to be the well where the initial discovery of megafaunal boneswas made in the late 1870s (Wilkinson 1885). The well is wood lined andis four feet (~1.2 m) square. There is a 12x12-foot (~4 m) fence made ofCallitris sp. logs surrounding the well. The preliminary results of the 1997 excavations have provided aclear insight into the structure of the upper claypan deposits, thelocation of the previous excavations of 1933 and the original well. Thepresence of cow bones in the upper metre of overburden (lying over thedeflation surface) and in a number of locations across the excavatedtrench is further evidence of the disturbed nature of these sedimentssince European occupation. No cow bones, other introduced fauna or dingo dingo(dĭng`gō), wild dog (Canis lupus dingo) of Australia, believed to have been introduced thousands of years ago from SE Asia by the aboriginal settlers of that continent; currently regarded as a subspecies of the gray wolf. have been found in the assemblages from the deflation pavement or theunderlying Pleistocene deposits. This is taken as an indication that thehuman/megafauna association has not been contaminated by intrusivematerial. The overburden is also massive in structure, in contrast tothe stratified horizon containing the megafauna/human association. Thepollen/geomorphological evidence also supports this interpretation(Field et al. in press). Progress in investigating the site has been slow during the lastfew years, mainly due to the ephemeral nature of the lake. Localthunderstorm activity can result in inundation INUNDATION. The overflow of waters by coming out of their bed. 2. Inundations may arise from three causes; from public necessity, as in defence of a place it may be necessary to dam the current of a stream, which will cause an inundation to the upper lands; of the claypan. Dependingon the time of year and the depth of water (usually ~30 cm), the claypancan take months to dry. In 1997 excavation was again complicated byunpredictable rain squalls, with partial inundation of the site. Thefield season focused on test pitting across the exposed excavation area,targeting Archaeological Levels 2, 3 and 4. The site is now primed forfurther excavation of Archaeological Levels 1 and 2, horizons whereflaked stone artefacts and the bones of megafauna are found inassociation. Further studies at the Cuddie Springs site are improving ourunderstanding of human interaction with megafauna. Using conservativeestimates of human arrival, the Cuddie Springs sequence indicates aclear overlap of megafauna with people for at least 10,000 years(O'Connell & Allen 1998). Cuddie Springs may be representativeof the events taking place through the arid zone in the lead up to theLast Glacial Maximum. Waterholes were drying up, larger animals startedperishing because they were incapable of moving to better-watered areas,and people expanded their resource base to maintain a presence in anuncertain environment. Current evidence suggests that megafauna andsmaller animals were initially targeted resources. Plant resources,including seeds became more important as higher-ranked resourcesdeclined (Furby 1995; Fullagar & Field 1997). In summary, the discovery of cow bones at the base of theundifferentiated clays provides us with conclusive evidence forextensive bioturbation bi��o��tur��ba��tion?n.The stirring or mixing of sediment or soil by organisms, especially by burrowing or boring.[German : bio-, bio- + Latin turb of the upper sediments, while at the same timeproviding an in situ taphonomic correlate for the earliestarchaeological level. The extent of the deflation pavement, thecontinuity of that surface and the absence of any major surfacedeformations are all indications that it has not been breached by modernmaterial, nor reworked in any significant way. The evidence for theintegrity of the deflation pavement, and by default the underlyingPleistocene sediments, has been critical in eliminating the possibilitythat stone artefacts may have been introduced to the Pleistocene unitfrom more recent levels. Importantly, the OSL data, the archaeologicaland environmental evidence as well as the stratigraphic data from the1997 excavations, support an interpretation of an intact record ofmegafauna and people in the lead up to the LGM (Field & Dodson 1999;Field et al. in press; cf. Roberts et al. 2001) Acknowledgements. Excavations were funded by an ARC Large ProjectGrant and the Australian Museum and facilitated by the Brewarrina LocalAboriginal Land Council, the Johnstone, Green and Currey families andmany volunteers especially Leanne Brass, Megan Mebberson, Harry Webberand Agnes Dubost. Thank you to Richard Cosgrove for comments and AndrewWilson for FIGURE 2. We are also grateful to Miralwyn Cotton and theWalgett Shire Council Walgett Council is a local government area in the Orana region of New South Wales, Australia, bordering Queensland on the north. Walgett, New South Wales is at the junction of the Barwon River and the Namoi River, and at the junction of the Kamilaroi Highway and the Castlereagh for assistance. Field was the recipient of an ARCPostdoctoral Fellowship and a University of Sydney The University of Sydney, established in Sydney in 1850, is the oldest university in Australia. It is a member of Australia's "Group of Eight" Australian universities that are highly ranked in terms of their research performance. U2000 PostdoctoralFellowship while undertaking this project.TABLE 1. Radiocarbon and OSL determinations for the Cuddie Springssequence. The sediment facies are also shown.sediment facies AL/SU radiocarbon age * lab. no.surface AL6 1470 [+ or -] 70 Beta 81,385 SU1undifferentiated clays AL5 14,820 [+ or -] 70 Beta 81,376 SU2-4 5,590 [+ or -] 60 Beta 81,375 19,270 [+ or -] 320 Beta 44,374deflation pavement AL4 28,770 [+ or -] 300 Beta 81,377 SU5clay/silts AL2&3 32,900 [+ or -] 510 Beta 81,378 SU6a 28,310 [+ or -] 200 Beta 46,170 33,660 [+ or -] 530 Beta 81,379 30,280 [+ or -] 450 Beta 44,375structured clays AL1 33,300 [+ or -] 530 Beta 81,379 SU6b 30,990 [+ or -] 360 Beta 81,380 32,580 [+ or -] 510 Beta 81,382 29,570 [+ or -] 280 Beta 46,171 32,420 [+ or -] 460 Beta 81,383 29,170 [+ or -] 360 Beta 81,384beach lag deposit SU7sediment facies OSL age lab no.surfaceundifferentiated clays 16,700 [+ or -] 1200 #deflation pavement 27,000 [+ or -] 2000 #clay/silts 30,000 [+ or -] 2000 #structured clays 36,000 [+ or -] 3000 # 35,400 [+ or -] 2800 [ANU.sub.OD]118abeach lag deposit >36,000 years not dated* dates are presented in stratigraphic order; # data obtained fromRoberts et al. 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