Analysis of a Late Quaternary Deposit and Small Mammal Fauna from Nettle Cave, Jenolan, New South Wales. Deborah A. Morris', M.L. Augee', D. Gillieson^ and J. Head^ 'School ofBiological Science, University ofNSW, Sydney NSW 2052; ^School ofGeography and Oceanography, University College, University ofNSW, Australian Defence Force Academy, CanberraACT2600; ^Radiocarbon Laboratory, AustralianNational University, Canberra ACT2601. Morris, D.A., Augee, M.L., Gillieson, D. andHead, J. (1997). Analysis ofalate Quaternary deposit and small mammal fauna from Nettle Cave, Jenolan, New South Wales. ProceedingsoftheLinneanSocietyofNewSouthWales111: 135-162 Adeposit ofsmall mammal bones in Nettle Cave, partoftheJenolan Caves system, was excavated. Thebone depositappears to be the resultofowl pellet accumulation. A pair of Sooty Owls {Tyto tenebricosa) currently inhabits a roosting site within the cave. The depositwasexcavatedtoadepthof68cm, whichrepresents anaccumulationthroughoutthe last glacial recession in the late Pleistocene to the present. Two radiocarbon dates (7,140 ± 280and8,730±280BP) wereobtainedfromdiscretecharcoallenses inthemiddlelayersof the deposit. Analyses ofsmall maimnal remains and sediments indicate climatic conditions duringthelatePleistocenewerecolderanddrierthanatpresent,becomingwarmerandwetter intheHolocene. The apparentabruptextinctionofBurramysparvusandtherapiddecline in abundance ofMastacomysfuscus in the Jenolan area are attributed to a briefhumid period thatoccurredinsoutheasternAustraliaataround 15,000to 14,000BP. Manuscriptreceived 1 June 1996,acceptedforpublication23October 1996. KEY WORDS: Nettle Cave, owl pellet accumulation, Tyto tenebricosa, late Quaternary, Burramysparvus,sediments,climate. INTRODUCTION Fossil deposits have long been used as a basis for the interpretation of past envi- ronments. In Australia, various Quaternary cave deposits have been analysed and used to reconstruct the faunal and climatic history of the surrounding area (e.g., Balme et al. 1978, Baynes 1987, Baynes et al. 1976, Hope et al. 1977, Porter 1979, Wakefield 1972). Deposits containing small mammal remains have been found to be particularly useful (Lundelius 1963). Little fossil material hadbeen foundinJenolan Caves until acollection ofbones was analysedfrom a small cave overlooking the lowercarpark (Hope 1979). Infrequent discov- eries of isolated skeletal remains from various caves have been reported in subsequent years. This study involvedexcavation ofafossil depositin Nettle Cave, part oftheJenolan Caves system. Theexcavationyielded an abundanceofintactsmall mammal bones, includ- ing those belonging to now locally extinct taxa, together with avian postcranial material andafew agamidandscincidmandibles (which are notdiscussedinthispaper). MATERIALS, METHODS AND STUDY AREA The Jenolan Caves Reserve is situated on the Great Dividing Range (33°47'S, Proc.Linn.Soc.n.s.w., 117. 1997 136 LATEQUATERNARYDEPOSIT A B C D Figure 1.PlanofNettleCave,Jenolan,withtheareaofheaviestdepositionofowlpelletsoutlined(lowercave). The highlighted area is the quadrat selected randomly for excavation. This area was further subdivided into quarters as shown in the insert. The quadrat and the subdivided areas are notto scale. Thecurrent Sooty Owl roostisindicatedbythearrow(uppercave),(modifiedfromCoxatal. 1989). 150°02'E; 1,100-1,200 m a.s.l.) approximately 110 km west of Sydney. This area has a maximum yearly mean temperature of 16.6°C and a minimum of 8.0°C (recorded at Katoomba - approximately 30 km from Jenolan). The average annual precipitation is 1,412 mm with the greatest rainfall occurring between December and June. The vegeta- tion within the Jenolan Caves Reserve supports eight major vegetation communities (Lembit 1988) ranging from open forest to cleared land. Nettle Cave is a high-level entrance into the Devil's Coach House, which is itselfa natural tunnel approximately 80 m high and 40 m wide (Cox et al. 1989). Flowstone forms a false floor in Nettle Cave (Anon. 1988). Cave conditions are dry (Nettle Cave is about 20 m above modern flood levels), with an annual temperature range from below zero to SO'C (Cox et al. 1989). The cave receives light from the entrance in the south, from a roof-hole in the northeast and from Arch Cave in the southwest (Fig. 1). The fossil deposit examined in this study is concentrated beneath a rock ledge in the roof of Nettle Cave close to the northern wall of the lower cave (Fig. 1). A pair of Sooty Owls (Tyto tenehricosa) currently occupies a nocturnal roosting site in the north- facing wall of the upper Nettle Cave (Fig. 1). Sooty Owls were first reported roosting in Proc.Li.nn. Soc.n.s.w., 117. 1997 D.A.MORRIS,M.L.AUGEE,D.GILLIESONANDJ.HEAD 137 Loosepowderysoil Bone-richsediments a u - 10 U Darkorganiclayerwilh > carbonatec u Browngrittysandyclay 20 withreducedbone content a 30 - jL~"r"- ""^^"^.c-^i"'::^z -/^^z^^ C(hAaNrcUoa7l89l7e)ns Whitecalcareous Charcoallens (ANU7898) 40 Yclealylowwitbhrwoewankgravelly Figure 2. Stratigraphy ofthe upperlevels ofthe southern wall ofthe excavated pit in the owl pellet deposit. NettleCave. Nettle Cave late last century by Jeremiah Wilson (the first official guide at Jenolan) (E. Holland, pers. comm.). The nocturnal roosting site is thought to communicate with the rock ledge in the lower cave by a tunnel in the roof of the cave (E. Holland, pers. comm.). The pair of Sooty Owls appears to roost diumally in the roof of the Devil's CoachHouse. In July 1990, owl pellets and bone material associated with disintegrated pellets m were collected from the surface ofan area ofapproximately 2 x 2 directly beneath the rock ledge in the roof ofthe lower Nettle Cave. On 10 January 1991, three fresh pellets m were collected approximately 4.5 from the northwestern wall ofthe lowercave. Excavation Excavation of the deposit began in January 1991. An area measuring 1.5 x 1.5 m was pegged over the site of heaviest deposition with one side abutting the northeastern wall (Fig. 1). A test dig was begun adjacent to the pegged area; its dimensions were about 50 X 50 cm and 58 cm deep. The dig proved to be rich in bone to this depth. Charcoal lenses were found at 28 cm and 35 cm. A quadrant measuring roughly 75 x 75 cm was chosen at random for excavation (Fig. 1). A section drawing of the southern wall of the excavation is shown in Fig. 2. Spits (defined in this paper as arbitrary vertical divisions, with respect to the stratigraphy in the deposit) from 0-5 cm, 5-13 cm, 13-25 cm and 25-35 cm were excavated. The Proc.Linn.Soc.n.s.w., 117. 1997 138 LATEQUATERNARYDEPOSIT depositto 35 cm below thepresentcavefloorwas rich in bone. Below 35 cm the main excavation was subdivided into four areas ofroughly equal size (A, B, C and D) (Fig. 1) and excavated separately. Two centimetre layers (here defined as natural vertical intervals of sediments, in which conditions of formation in each layer appear to have been consistent) were removed, following the line ofthe sedi- ment, from 35 to 41 cm. These layers contained less bone than above. The bones were found in association with small aggregates of sediment cemented by calcium carbonate. A limestone outcrop was apparentat 37 to 41 cm on the eastern wall ofthe pit, butreced- edbeyondthe wall ofthepitbelow41 cm. The sediment was heavily cementedby calciumcarbonatebelow41 cm. Excavation ofquadrants A and C (Fig. 1) became impossible. Excavation ofquadrants B and D from 41 to44cm waspossible by using the sharp endofatrowel tobreakup the sediment. At 44 cm the sediment from quadrant D and the outer part of quadrant B was so firmly cemented that furtherexcavation ofthis section ofthe pit with the hand-held imple- ments available was impossible. The remainderofquadrant B containedbone in arelative- ly softsediment. This areawas excavatedto adepthof68 cm. Spits rangingfrom2 to5 cm in depth were removed from 44 to 68 cm of the excavation. Excavation ceased in April 1991 at a depth of68 cm, despite bone being visible below this point. The excavation was not backfilled as is customary because the Jenolan Caves Scientific Advisory Committee planstolinethewalls oftheexcavationwithperspexcovers andusethepitas anexhibit. SedimentSamples Sediment samples were taken every 5 cm, or every 2 cm ifthe stratigraphic layer was narrower, from the inner part ofthe southern wall ofquadrant B (Fig. 1). A total of 16 samples was taken to a depth of64 cm. The pH ofeach sample was determined in the field by using a CSIRO test kit. The method of measuring particle size and the particle size classification follow Folk (1968). Carbon Samples Although minor amounts of charcoal were present throughout the levels (here defined as any point on the vertical axis ofthe deposit) ofthe excavation, usable quanti- ties were only located in two lenses at 28-29 cm and 35-36 cm depth in the western wall of the main pit. The lenses were sampled for radiocarbon dating using the methods of Gupta and Polach (1985) and submitted to the Australian National University Radiocarbon Laboratory. For sample ANU-7897 (Nettle Cave 28-29 cm), possible cont- aminants were removed and the sample washed in hot 10% HCl, rinsed and dried to remove possible carbonate. For sample ANU-7898 (Netde Cave 35-36 cm), the sample was wet sieved and the fraction <500 um taken for dating. After solvent extraction, the sample was washed in boiling HCl, and NaOH insoluble residue (non-humic) was re- acidified, rinsed and dried. Preparation ofthe Bone Remains All surface material and subsamples from 0-5 cm were washed in water and air- dried. Material from 13 cm downwards required acid treatment (10% acetic acid for seven days) for separation ofbone from matrix. Levels 5-13 cm and 39^1 cm were not analysed because oftime constraints. Identification ofMammalian Material Each depth interval (here defined as a vertical division between two measured lev- Proc.Linn. Soc.n.s.w., 117. 1997 D.A.MORRIS,M.L.AUGEE,D.GILLIESONANDJ.HEAD 139 els within the excavation, e.g. 0-5 cm) was analysed separately. The upper levels of the deposit contained relatively more intact maxillary and dentary specimens than the lower levels. All maxillary and dentary material bearing teeth or with tooth sockets, and isolat- ed teeth were identified. Marsupials and rodents were identified by comparing maxillary and dentary frag- ments and isolated teeth with published descriptions (Appendix A) and with reference specimens held at the University ofNSW and the Australian Museum. Microchiropteran specimens were identifiedby S.J. Hand. Dental nomenclature of marsupials follows Luckett (1993). Marsupial specimens were considered to be juvenile if the P3 and/or M4 had not fully erupted. Edentulous mandibular specimens were regarded asjuvenile according to size variation recorded in the literature andby comparison with reference material. Nomenclature generally follows that ofWalton (1988) and Walton and Richardson (1989). Pseudocheirus peregrinus and Petauroides volans are referred to Pseudocheiridae (Archer 1984), and Acrobates pygmaeus to Acrobatidae (Aplin and Archer 1987). The identified mammalian and unidentified avian material will be lodged at the Australian Museum (the reptile specimens were sent to the South Australian Museum for identification and cataloguing, and are lodgedthere). QuantitativeMethods In order to make inferences regarding the composition of the mammalian assem- blage, the minimum number of individuals (MNI) of each taxon represented in each analysed depth interval was determined. Estimation of the MNI follows Baynes et al. (1976). Identifiablerightand leftdentaries andmaxillae werecounted separately. The most numerous element was taken as the MNI. Relative abundance was taken as the percentage of all species occurring in each depth interval. (These percentages give a more accurate representationofeachspeciesfromdepthinterval todepthintervalthandoes theMNI.) RESULTS Sedimentary Analyses Stratigraphy A section drawing of the southern wall of the excavated pit is shown in Fig. 2. Because cementation by calcium carbonate made definition of the stratification of the lowerlayers difficult, only the top 40 cmofthe excavation are shown. The gross stratigra- phy ofthe bone-rich sediment suggests these sediments had formed as a result ofa series of deposits of air-fall debris. The dark organic layer indicates a stable surface. The sedi- ment changed below this layer to a brown, gritty, sandy clay that contained an increased amount ofcharcoal and soil particles, but a reduced amount ofbone. Two discrete lenses of charcoal were evident. Between these lenses was a white, calcareous, cemented layer which may represent a former water saturation level. The sediment below this cemented layerto the base ofthe pit contained a yellow-brown, gravelly clay which may have been the resultofwaterponding in thecave. There was noclearstratificationbelow40cm. SedimentChemistry The field pH measurements were uniformly 9.5 for the 16 sediment samples. An alkaline environmentpromotes the precipitation ofcalcium carbonate out ofsolution and the rapiddecomposition oforganic material by bacteria andfungi (Levinson 1982). Radiocarbon Dates Radiocarbon ages are reported in Table 1 as conventional years BR d^-^C values were estimated and given an error of 2.0 permil. The two radiocarbon ages are signifi- Proc.Linn. Soc.n.s.w., 117. 1997 140 LATEQUATERNARYDEPOSIT cantly different (p>0.05). Table 1 RadiocarbonagesofcharcoalfromtheNettleCavedeposit. Sample Depth dl4C 813C D14C age code (cm) (permil) (permil) (permil) (yearsBP) ANU-7897 28-29 -587.8±13.7 -24.0±2.0 -588.6±13.8 7,140±280 ANU-7898 35-36 -661.9± 11.4 -24.0±2.0 -662.6± 11.5 8,730±280 Source ofthe Sediment Mineral magnetic results from the Nettle Cave sediment samples are compared with data from other sites in the Jenolan Caves catchment (Stanton 1989) in Table 2. The results indicate that the Nettle Cave sediments are distinct from these possible sources andespecially from the MammothCave fluvial sediments. Table 2 Meanmagneticparametersfordifferentsedimentsourceareas,Jenolancatchment. SIRMdenotes saturationisothermalremanentmagnetisation. DataotherthanthatforNettleCavefromStanton(1989). Mean Meanfrequency Mean Sourcearea susceptibility dependentsusceptibility SIRM NettleCave 1.43 9.9 20.6 TerraceCreek 4.24 6.9 41.4 Jenolan-Bindo 4.41 7.9 49.6 CreekDivide I WesternRidge 9.24 4.2 109 MammothCave 4.24 5.4 39.9 Fines MammothCave 3.7 5.2 32.5 Coarse Particle size analysis can provide some information on sediment transport and deposition (Krumbein and Sloss 1963). The relative amounts (by weight) ofgravel, sand, silt and clay in each sample from the Nettle Cave deposit are illustrated in Fig. 3. (Unfortunately, bone was included in the gravel fraction; ifbone had been excluded, the relative proportions ofsand, silt and clay would be greater than that suggested in Fig. 3.) The greatest fluctuations, albeit minor, were in the proportions of gravel and then sand. An increase in the amount of fine material occurred around 37 cm. This increase was coincident with water ponding of the top layer in the lower zone ofthe deposit. The pre- ponderance of coarser, angular particles in the sediment samples suggests that the sedi- ment is of local origin and has not been subjected to lengthy fluvial transport. Proc.Linn.Soc.n.s.w., 117. 1997 . D.A.MORRIS,M.L.AUGEE,D.GILLIESONANDJ.HEAD 141 45 42 37 32 DEPTHINTERVAL(CM) Figure 3. Graphical representation ofthe amount ofgravel, sand, silt and clay (by weight) in the sediments fromtheNettleCavedeposit. Considering the mineral magnetic data and particle size of the Netde Cave sediments, these sediments are likely to have originated from local soil above the cave. Moreover, the relatively minorfluctuations in the proportions ofthe sediments throughout the depth ofthe deposit suggestthere was little variation in the source ofthe sediments. Mammal Faunafrom the Nettle Cave Deposit Thirty-five species of mammals were identified in the Nettle Cave deposit (Appendix B). Ofthese species, 74% are extant and 26% are extinct either locally or in southeastern Australia. If a species is present in an upper or lower level of the deposit, it tends to appear throughout the upper or lower zone of the deposit, respectively (Table 3). The distribu- tion ofsome species at41 to 44 cm appears tobe discontinuous. The majority of the species occurring throughout the deposit (Table 3) are small animals weighing less than 200 g. All these specimens are adult. The larger species pre- sent, e.g. Dasyurus sp., P. peregrinus, Isoodon obesulus and Perameles nasuta, are rep- resentedby subadults. Species with restricted habitat requirements and range ofdistribution are the most useful indicators ofenvironmental conditions (Baynes et al. 1976). The changes in rela- tive abundance with time of selected non-volant, small mammal species from the Nettle Cave deposit are illustrated in Fig. 4. These species were selected as indicators ofpossi- ble environmental change in theJenolan areaforthe following reasons: 1 the species showed achange in distribution overtime or, 2. the species showed achange in abundance overtime and Proc.Linn.Soc.n.s.w., 117. 1997 . 142 LATEQUATERNARYDEPOSIT Table 3 SummaryofAppendixB:Presenceorabsenceofspecimensidentifiedfromeaciidepthintervalfromthe NettleCavedeposit.Presenceofspeciesinadepthintervalisindicatedbyablackblock.Depthintervals 13-5cmand 41-39cmwerenotanalysed,andarerepresentedasnarrow,blankbars.S=numberofnon-volantmammalspeciesin thedeposit.n=sumoftheMNIsofnon-volantmammalspecies,exceptingA.spp.,S.sp.,P.spp.andR.spp. 1 Presenceofbatsinadepthintervalisindicatedbyadashedblock,buttheMNIisnotincludedinn.2.Presenceof birdsisindicatedbyadashedblock;specimenswerenotidentifiedaboveorder.3.Skinkswerepresentindepth intervals5-0cmand25-13cm;agamidswerepresentindepthintervals5-0,25-13,35-25,37-35and39-37cm. SPECIES Antechinusstuartiisensulato A. swainsonii A.flavipes A. spp. Sminthopsismurina S. sp. Phascogaletapoatafa Dasyurussp. cf. D. viverrinus Isoodonobesulus Peramelesnasuta Pseudocheiriisperegrinus Petauroidesvolans Petaurusbreviceps Cercartetusnanus C. lepidus Biirramysparvus Acrobatespygmaeus Potoroussp. cf. P. tridactylus Bettongia sp. Thylogalethetis Conilunisalbipes Pseudomysoralis P. gracilicaudatus P. australis P. novaehollandiae P.fumeus P spp. Mastacomysfuseus Rattusfuscipes R. rattus R. spp. Musmusculus Oryctolaguscuniculus Bats' Birds- Lizards' CO^O CO7^- O4^- '^J\ '4J-\ 'O'^ O'N '.tj '->j '-h> —^ '/• ^ 5' P OrCIv-J'-rOI,^t-vr'IJ,D\-lr'-—I,f\ 'r0.I,f\0^OJr-;^-t-44r';--->'4oJ.->J —iO—- —'O—^Il'-''OV_ylui'-'Ot-//o)>''rjj;jJ|---3;^ r5'r^^j> -c \-t yi — — C-^T'-'^^ —O O—--jJ l4'--'o1 ——xC ^—--J Oo4-^—ID Proc.Linn.Soc.n.s.w., 117. 1997 D.A.MORRIS,M.L.AUGEE,D.GILLIESONANDJ.HEAD 143 3. the species' habitat requirements are both well-documented andrestricted. ModernMammal Fauna in theJenolanArea The term 'modern mammal fauna' is used to describe the fauna inhabiting, or thought to inhabit, the Jenolan area since European settlement. Of the 35 mammal species recovered from the Nettle Cave deposit (Table 3), one {Conilurus albipes) is pre- sumed to be extinct (Watts and Aslin 1981); eight {Dasyurus viverrinus, Cercartetus lep- idus, Burramys parvus, Bettongia sp., Pseudomysfumeus, Pseudomys australis, Pseudomys oralis and Mastacomysfuscus are extinct in the area (Strahan 1995; Watts and Aslin 1981); Pseudomys gracilicaudatus had previously occurred this far south (remains were found in superficial deposits at Walli Caves near Canowindra and Wombeyan Caves [Mahoney and Posamentier 1975]); the status ofPhascogale tapoatafa and Pseudomys novaehollandiae in this area is uncertain (Strahan 1995; Watts and Aslin 1981); theremaining 23 are locally extant (Strahan 1995). DISCUSSION Age ofthe Deposit The age ofspecimens in the Nettle Cave deposit can be estimated when associated with stratigraphy, otherfauna, radiometric dates and the appearance ofthe material (after the mannerofBaynes (1987)). Two radiocarbon dates based on charcoal samples were obtained from the middle levels ofthe deposit (Fig. 2). Ifone assumes aconstantrate ofaccumulation ofsediments to the base ofthe excavation at68 cm, then this level may represent 16,000-14,000 years BR However, ponding and a change in the nature of sedimentation is evident below 35-36 cm (Fig. 2). In addition, abrupt changes in the faunal assemblage around 41^3 cm may indicate either a hiatus in deposition, or a minorunconformity (period ofnonde- position or erosion) in the deposit (Krumbein and Sloss 1963). Conversely, changes in the composition ofthe material being deposited may have produced the change in strati- fication (Dunbar and Rodgers 1963). For example, changes in grain size may cause pro- nounced layering. Therefore, this time frame on the basis of sedimentation should be treated with caution, since charcoal was not available at the base ofthe pit to allow more precise dating. Environmental History atJenolanbased onNettle Cave Sediments Although real precipitation atthe end ofthe Pleistocene was reputedly low (Dodson 1977; Galloway 1965), seasonal melting of the snow would have made available free water. A study by one ofus (D.G., unpublished data) suggests the influx of subsoil parti- cles to the lower levels ofthe Nettle Cave deposit indicates erosion ofthe topsoil overly- ing the cave either due to hillslope instability (Gillieson et al. 1985) or thawing of the ground and subsequent washing away ofthis surface material. Wind activity would have contributed to the erosion to some degree. More importantly, wind activity is a selective barrier in the transport ofparticular grains. Coarse particles such as gravel are left behind or deposited close to the source forming a local accumulation. Fine grains (silt and clay) are kept in suspension and transported over long distances (Krumbein and Sloss 1963; Pettijohn 1957; Reineck and Singh 1975). These conditions are reflected in the relatively low amounts ofsiltandclay in the Nettle Cave sediments (Fig. 3). The sediment in the levels of the deposit around 44-41 cm consists of a yellow- brown, gravelly clay which was probably the result of local water ponding in the cave. Proc.Linn.Soc.n.s.w., 117. 1997 LATEQUATERNARYDEPOSIT 144 A) MA.pygmaeus HP.volans HP. breviceps » 25 MP.peregrJnus < Ed ^ 20 LIO L8 L6 SURFACE DEPTHINTERVAL DA.swainsonii C.nanus SB.parvus SC.lepidus Jl- JIl SURFACE L16 L8 DEPTHINTERVAL Figure4 Therelative abundanceofselected non-volant, native mammal speciesfrom the NettleCavedeposit. The species represented are possible indicators ofclimatic change. Levels L2 and L7 were not analysed. See AppendixBforthecorrespondingdepth interval toeach level.Continuedon followmgpage. Proc.Linn. Soc.n.s.w., 117. 1997