Geology of the Flinders Ranges National Park
Oraparinna
Brachina Gorge
Slippery Dip
Aroona Ruins/Cultural Heritage Site
Bunyeroo Valley
Sacred Canyon Cultural Heritage Site
Arkaroo RockCultural Heritage Site
St Mary Peak St Mary Peak St Mary Peak St Mary Peak St Mary Peak St Mary PeakMalloga Falls
To Black Gapvia Heysen Trail
BridleGap
To Hawker40 km
Bunyeroo Bunyeroo Bunyeroo Bunyeroo Gorge Gorge Gorge Gorge Gorge
Bunyeroo Gorge
HucksLookout
Stokes HillLookout
To Leigh Creek100 km
Appealinna RuinCultural Heritage Site
Dingley Dell
Youngoona
Trezona
Yanyanna Hut
To Arkaroola160 km
WilkawillinaGorge
Koolamon
To Parachilna Gorgevia Heysen Trail
To Blinman13 km
Cambrian
AcramanCampground
Red HillLookout
BrachinaEast
Teamsters
Aroona Valley Aroona Valley Aroona Valley Aroona Valley Aroona Valley
BunyerooValleyLookouts
WILPENA
POUND
PerawurtinaCulturalHeritage Site
Rawnsley Bluff
Wilpena
Elatina Hut
Mt OhlssenBagge
TanderraSaddle
Dedman's Hut
Great Wall of China
To Hawker viaMawson Trail
CooindaCampWangarra
Lookout
HillsHomestead
Brachina
Self
Guided Drive
Water (may be insprings/creeks)
Phone
Fuel
Accommodation
Caravan camping
Vehicle based camping
Bush camping
Ranger station
Self-registration station
Lookout
Bus parking
Heysen Hut
Park boundary
Sealed road
Unsealed road
Walking trail
Walking trail(mentioned in this brochure)
Heysen Trail
Mawson Trail
Ruin
Building
Information
Toilets
Parking
Hawker
CarrietonQuorn Port
Augusta
Wilmington
Copley
Marree
WirrealpaBlinman
Parachilna
LeighCreek
Lyndhurst
To Innamincka
Gammon RangesNational Park
Lake
Torrens
National
Park
Strzelecki Track
Lake FromeRegionalReserve
Flinders RangesNational Park
MER 203996
Walk safely
Be prepared when bushwalking:
•Wearsturdyshoes,hatandsunscreen.
•Carrysufficientfoodanddrinkingwater—allow4litresofwaterperpersonperday.Donotrelyontanksorcreeksintheparkfordrinkingwater.
•Keeptothedefinedwalking.trail.
•Informaresponsiblepersonofyourproposedrouteandexpectedtimeofreturn.
•Weatherconditionscanchangequickly;ensureyouhaveappropriatewetweatherclothing.
TrailTime *DistanceTrail NotesClassification
Wilkawillina Gorge Hike6hoursone-way
11.4kmone-way
Habitatofyellow-footedrockwallaby;uniquegeologicalfeatures.
Hard
Bridle Gap Hike6hoursreturn
18.8return
TheWilpenaPoundisfilledmainlywithrecentalluvium;observewildlifethroughthePound.
Hard
Bunyeroo and Wilcolo Creeks Hike
5hoursreturn
9.2kmreturn
Nativepinegrovesalonghilltops;cool,gum-linedcreeks.
Moderate
YulunaHike4hoursloop
8kmloopThishikeleadsthroughthelandscapethatinspiredartistHansHeysenonhisnumerousvisitstotheFlindersRanges.
Moderate
Haywards Huts Hike Network
TrezonaHike4hoursloop
8.2kmloop
DiscoverfossilsofsomeoftheearliestlifeformsonEarthintheTrezonaFormation.
Hard
AroonatoYoungoonaHike
7hoursone-way
15kmone-way
Alinearwalkacrossthepurpleshaleofthenativepine-cladABCRangetothelimestoneoftheTrezonaRange.
Hard
St Mary PeakHike
directroute(outsidetrail)
6hoursreturn
14.6kmreturnBreathtakingviewsof
thecentralFlindersRanges.
Hardlooproute(insidetrail)
9hoursreturn
21.5kmreturn
Heysen Trail1500km
TheHeysenTrailisgenerallyopenfromApriltoOctobereachyear.ItisclosedduringtheFireDangerSeason.Datesvaryfromsectiontosection,andfromseasontoseason.
*Time is generously estimated from an average walking speed of 2 km per hour –allow extra time for resting and sightseeing.
HIKE – Moderate•somemoderateinclines•irregularsurfacewithloose,unevenbase
•averageleveloffitness
HIKE – Hard•somesteepinclines•irregularsurfacewithloose,unevenbase
•averageleveloffitness•somehikingexperience
Heysen Trail cont.Thesouthernsection,fromCapeJervistoSpaldingintheMidNorth,followstheMountLoftyRangesandisidealforbeginnersandthosewithchildren.Thenorthernsection,fromSpaldingtoParachilnaGorge,isisolatedandattimesrugged,providingarewardingchallengeforexperiencedwalkers.
Thetrailhasbeendesignedtocaterforboththeseriousbackpackerwalkingthecompletelength,andforthedaywalkerwhomightchoosetodoshortwalksalongdifferentsections.Forfutherinformationsee<www.environment.sa.gov.au/parks/pdfs/FLRA_PDFS_PARK_GUIDE.PDF>and<www.heysentrail.asn.au/heysen_trail/>.
ThestoryoftheFlindersRangesbeganmorethan800millionyearsagoduringtheNeoproterozoicEra,whentheEarthwasundergoingmajorchangesinitscrustandsurfaceenvironments.Thelandwasdevoidofplantsandanimals,andtheoceanswerepopulatedonlybymicroscopicorganisms.Itwasalsoatimeofbreak-upofverylargecontinentallandmasses,similartothemuchlater(about100millionyearsago)break-upthatformedthepresentcontinents.
TheFlindersRangespresentamagnificentrecordofEarthhistory.Withcarefulobservations,therocksdisplayedintheruggedrangesandcolourful,gum-linedgorgescanbereadlikeabook,takingusonalongjourneythroughtime.Thishistoryisrepresentedinasuccessionofrocklayers,nowtiltedanderoded,andhenceaccessibleattheEarth’ssurface.Thelayersconsistofdifferenttypesofmainlysedimentaryrocks,eachdepositedunderdifferentconditionsofenvironmentandsedimentsupply.Theserocklayers,termedformations,areeachuptohundredsofmetresthick.Theyrecordrepeatedadvancesandretreatsoftheseaandchangesinclimate,includingtwomajoriceages.
TheoldestrocksseenintheFlindersRangesNationalPark,theCallannaGroup,providecluestotheearliestoriginsoftheranges.Foundonlyintwolargestructuresknownasthe
OraparinnaandEnoramaDiapirs,theserocksarebrokenanddisruptedsedimentarybedsoriginallydepositedinshallow,restrictedseas,coastallagoonsandsalinelakes.Castsofsaltcrystalsarecommonlyfoundontheunder-surfacesofbeds.Lavaflowsandashfallsrecordedinthesesedimentswerederivedfromvolcanicactivityasmoltenrockrosealongdeepfracturesinthecrust.
Atthistime,about800millionyearsago,theEarth’scrustwaspulledapartandthinned,forminganextensivesedimentarybasinastheseastartedtofilltheresultingdepression.Thisbasin,knownastheAdelaideGeosyncline,stretchedfromnearOodnadattatoKangarooIsland.
About700millionyearsago,severeclimaticcoolingledtoamajoriceage,whenglaciersandicesheetscoveredmuchofAustraliaandothercontinents.Theglaciersscoureddeepvalleysinthelandscape,pickinguprockdebristhatbecameincorporatedintheiceandwaslaterreleasedastheglaciersmelted.Suchglaciallyderivedsedimentistypicallyamixtureofmud,sand,pebblesandboulders;whencompactedandhardenedthisformsarockcalledtiIIite.Inthepark,thePualcoTilliteandthedarkred,ridge-formingHolowilenaIronstoneweredepositedduringthisglaciation.SiltstoneoftheoverlyingWilyerpaFormationrecordsgradualwarming,withoccasionalcobblesandpebblesdroppedfrommeltingicebergs.Prominentridge-formingsandstoneatthetopoftheWilyerpaFormation,forexampleneartheLovesMineRange,wasdepositedoff-shorebystormcurrentsfromsandfreedbymeltingicealonganancientshoreline.
Arapiddeepeningoftheseafollowed,duringwhichblack,organic-richmudsoftheTapleyHillFormationweredepositedthroughouttheAdelaideGeosyncline.
TheOraparinnaandEnoramaDiapirsfirstbecameactiveatthistime.TheoriginofthesestructuresisthoughttobeduetotheoriginalpresenceofsaltbedsintheCallannaGroup.Saltislighterandmoreductilethanotherrocktypes.Astheoverlyingpileofdensersedimentsthickenedwithcontinuingdeposition,thesalt-bearingmaterialbecameunstable.Faultingalongzonesofweaknessin
theunderlyingcrustmayhavebeenthetriggerthatinitiatedupwardmovementofthelessdensesedimentsoftheCallannaGroupundertheweightofthickoverburden.Thismovementdraggedupanddisruptedthebeds,formingabrecciaoffragmentsofsedimentaryrocks,aswellasblocksofvolcanicrock,fromtheCallannaGroup.
Atfirst,theoverlyingbedsweredomedupwardsasthesalt-bearingmaterialrose.Later,thediapirperiodicallybrokethroughtothesurface,anddiapiricbrecciaspilledoutontheseafloororonsmallupliftedislands.Thismaterialwasreworkedbycurrentsintothemarinesedimentsofthetime,forminglenticularconglomeratelayersasseen,forexample,intheTapleyHillFormationaroundthemarginsofthediapirs.Thefine-grained,grey-greensandstonebedsofMountCaernarvonrecordgradualshallowingofthebasinasitbegantofillwithsediment.
TheSunderlandFormationofthecentralFlindersRangesalsoconsistsoffine-grainedsandstoneandsiltstone,butitsbaseisanerosionalboundary,resultingfromadropinsealevelandmarkedbyathin,coarse-grainedsandstone.ChannelswerecutintotheunderlyingTapleyHillFormationandfilledwithooliticandpebblylimestone.Sealevelthenroseagain,
depositingfinergrainedsedimentsbut,asthebasinfilledup,shallowmarine,sandytogrittylimestoneoftheEtinaFormationaccumulated.Large,trough-shapedscoursindicatehigh-energywaveandcurrent-influencedenvironments.TheOraparinnaDiapirwasagainactiveatthistime,sheddingfragmentsofCallannaGrouprockstoformconglomeratelensesintheEtinaFormationadjacenttothediapir.Interbeddedgreen,siltyshalesrecordquieter,deepermarineepisodes,asdoestheoverlyingEnoramaShale.
TheTrezonaFormationmarksareturntonear-shore,tidallyinfluencedandlagoonalenvironments,idealforthegrowthofcyanobacteriawhichbuiltupstromatolites(seeStromatolites).
Atthistime,sealevelfellwiththeonsetofanotherglacialperiod.LimestoneoftheunderlyingTrezonaFormationwassubjecttodissolutionbyrainwater,producingakarsttopography.GlaciationisrecordedbythepebblysandstoneandlocaltiIIiteoftheElatinaFormation,containingglaciallyderivedpebbles,manystriatedorgroovedbyrocksgrindingagainsteachotherwhilecarriedbyice.
Aprominentyellow-weatheringpinkdolomite,theNuccaleenaFormation,wasthendepositedastheseaagainfloodedthebasinwithareturntowarmerclimates.Thethicksiltstoneandfine-grainedsandstoneoftheoverlyingBrachinaFormationinturnrecordsoverallshallowingofthebasin,culminatinginthedepositionofbeachsandmakinguptheABCRangeQuartzite.Cross-beddingandripplemarkswereformedbytidalcurrents,andmudcracksindicatethatthinclaylayerswereoccasionallyexposedanddriedout.
Afterabrieferosionalinterval,therewasanothermajormarinefloodingofthebasin.ThemonotonousredshaleoftheBunyerooFormationwasdepositedindeep,quietwater.Withinthisformation,auniquelayerofrockdebris,onlya
fewcentimetresthick,isthoughttorepresentthefall-outfromtheimpactofalargemeteoritethatstruckthepresentpositionofLakeAcramanonnorthernEyrePeninsulaatthistime.
Beforesedimentationwasabletofillthebasinagain,itwaspunctuatedinthesouthernandnorthernFlindersRangesbythescouringofcanyonsuptoakilometredeep,causedbyrenewedstretchingofthecrust.Theparkarea,however,wasmorestableandthisremarkableeventisrecordedbyaperiodofveryslowdepositionofaone-metrethick,bandedyellowdolomitemarkingthebaseoftheWonokaFormation.Thebasin,includingthecanyons,wasquicklyfloodedbythesea.Deep-watergreenshaleoftheWonokaFormationpassesupwardsintolimestoneandsandstonedepositedasthebasinagainbegantoshallow.Grazingtrailsofsmallworms,thefirstgoodevidenceofmarineanimallife,arefoundinthisformation.
TheWonokaFormationpassesupintotheredBonneySandstone.Ripplemarks,mudcracks,mudpebblesandcross-beddingrecordshallowdeltaicandtidalenvironments.
ThewhiteRawnsleyQuartziteformsthehighestbluffsandrangesoftheparkarea.Ittoowasdepositedinshallowmarineandpossiblyfluvialenvironments.Closetothebaseisaunitofsiltstoneandthinlybeddedsandstonewhichcontainsthefirstabundantevidenceofcomplexmarineanimallife(seeEdiacaraFauna).
AttheendoftheNeoproterozoicEraabout540millionyearsago,theseawithdrewcompletely.Afteraperiodofterrestrialerosion,thebasinwasagainfloodedatthebeginningoftheCambrianPeriod,whenthefirstanimalswithhardshellsevolved.IntheparkareathefirstCambrianrockunitistheParachilnaFormation,consistingofwhite,clayeysandstoneandsiltstonewithlong,verticalandU-shapedwormburrows.
Geological history of the Flinders Ranges
203996-002
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PortAugusta
Broken Hill
Arkaroola
Marree
WilpenaChalet
PortLincoln
ADELAIDE
SA
QLD
NSW
Initial stages in development of the Adelaide Geosyncline. Tectonic forces stretched and thinned the Earth’s crust, forming an extensive low-lying basin that was invaded by the sea. Volcanoes and lava flows formed along zones of crustal weakness.
Development of the Oraparinna Diapir. Initially, less dense Callanna Group rocks intruded zones of weakness in overlying sediments. As the diapir continued to rise, it breached the seafloor and detritus was shed into flanking sediments.
Sea
Diapir
Detritus Seafloor
INITIAL STAGE
LATER STAGE
Tapley Hill Formation
Wilyerpa Formation,Holowilena Ironstone,Pualco Tillite
Burra Group
Callanna Group
203996-001
Contact between the white Rawnsley Quartzite (weathering orange) and underlying red Bonney Sandstone, Brachina Gorge. (Courtesy of Bernd Stoecker; photo 044285)
Ripple marks in the Rawnsley Quartzite, Wilpena Pound, looking towards Chace Range. (Courtesy of Bernd Stoecker; photo 044287)
800 million years ago
Thefirstreefssimilar,forexample,totheGreatBarrierReefgrewinshallowwarmwatersduringtheCambrian,butthesewerebuiltnotbycorals,butbysponge-relatedanimals,nowextinct,calledarchaeocyaths.ThesearebeautifullypreservedinpartsoftheWilkawillinaLimestone.InWilkawillinaGorge,theParachilnaFormationismissing,andthelimestoneliesdirectlyovertheBonneySandstone.
Later,adropinsealevelcausedexposuretthereefs,formingakarstterrainwithmanysinkholesfilledwithiron-richsilt.
Thedarkgrey,organic-richlimestoneoftheMernmernaFormationwasdepositedasthebasinagainflooded,forminganextensiveseaforthelasttime.TheoverlyinggreenOraparinnaShaleincludesthefirsttrilobites,preservedinconcretions.Asthebasinagainbegantofillwithsediment,coarsesiltandsandweredeposited.Thebasinhadbecomeveryrestricted,allowingthedepositionofshallow-waterredsandandsiltoftheBillyCreekFormation
andLakeFromeGroup.However,thisdepositionwasinterruptedbyabriefmarineintervalrepresentedbytheWirrealpaLimestone.
SedimentationfinallyceasedwhenmajormovementsandheatingwithintheEarth’scrustbeganabout500millionyearsago.Bynowtheaccumulatedsedimentshadbeencompactedandcemented.Convergentmovementoftheancientstablelandmassesoneithersideofthebasincausedbucklingandupthrustingofthesedimentaryrocks.Theparkoccupiesabroad,deeplyerodedanticline,withtheoldestrocksinthecentreandstratatiltedinoppositedirectionseastandwestofthiscentralcore(cross-sectionAA’).WilpenaPoundformsagentlesynclineandtheMountBurnsareainthesouthwesterncornerofthemapformsatighteranticline(cross-sectionBB’).Duringbuckling,largefaultsandfracturesformedalongzonesofweaknessandre-activatedfaultsthathadbeenactiveduringsedimentation.
Duringfolding,thediapirsbecamethecoresoflargedome-shapedfolds.Thesalt-bearingdiapiricmaterialwasfurthercompressedandmobilised,andinjectedhigherintotheoverlyingrocks.Latererosionhascutthroughthedomes,providingaviewofthedeeperlevelsofthediapirs.
Asaresultofthismountain-buildingactivity,theancestralFlindersRangeswereborn.Weatheringanderosionimmediatelybegantoreducethemountainsastheyrose.Largeriverscarriedawayvast
amountsoferodedrocktotallingseveralkilometresinthickness,tofeedthedevelopingsedimentarybasinsineasternAustralia.Byabout100millionyearsago,theancestralrangeshadprobablybeenreducedtoalow,gentlyundulatinglandscape.Earthmovementsrelatedtothebreak-upofAustraliafromAntarcticathencausedreneweduplift.Duringthelast50millionyears,theFlindersRangeshavebeenrisingsteadily,andpersistentsmallearthtremorsindicatethatthisisacontinuingprocesstoday.
FluvialandlacustrinesedimentationoccurredinvalleyssuchasattheentrancetoBrachinaGorge.Softmudstoneunitswereerodedreadilytoformvalleys,whilehardrockssuchasquartziteremainedaspeaksandridges.ThespectacularBrachinaandBunyerooGorgeswerecutthroughbyriverswhichexploitedjointsandsmallfaultsinthesandstoneridges.Thesedynamicprocessescontinuetoshapetherangesbut,withadrierclimatetoday,sedimentaryprocessesarelimitedtooccasionalfloodeventswhenlargequantitiesofsand,gravelandboulders,aswellasup-rootedtrees,maybecarrieddown-stream.
Asyoucanseethereismoretotherangesthanfirstmeetstheeye.TheevidenceofthislongperiodofEarthhistoryisavailabletothekeenobserverofthecluespreservedintherocks.Thisunderstandingcanonlyenhancetheuniquebeautyoftheranges,oneofourmosttreasuredholidaydestinations.
Otherdiscsmayrepresentsoft,possiblytentacle-bearingpolypswhichwereattachedtotheseafloor.Alsopreservedasimpressionsontheundersidesofbedsareprimitiveworms,animalswithacoelome(bodycavity)ofarthropodaffinities,ancestorsofseaurchins,andsomecompletelyenigmaticforms.
Cambrian trace fossils TheU-shapedburrowsintheParachilnaFormationindicatethattheburrowingwormshadarigid,fluid-filledbodycavity.ThefactthattheysoughtshelterinburrowsindicatesthatpredatorsmusthaveevolvedbytheEarlyCambrian.
Cambrian shelly fossils TheCambrianlimestonescontainthefirstfossilsofanimalswithhardskeletons.Theseincludethecup-shapedarchaeocyaths,whichwereprobablyfilterfeedersrelatedtosponges,andwhichdiedoutlaterintheCambrianPeriod.Molluscs,includingsmallseasnailsandcockle-likeshells,brachiopods(Iamp-shells),andtheextincttrilobites,canalsobefoundintheCambrianlimestonesandshales.TheseanimalgroupsallappearedearlyintheCambrian,representingthemostdramaticexplosionofdiversityinthehistoryofevolution.
Fossils
Fourgroupsoffossilsarepresentinthepark:stromatolites,theEdiacaraFauna,tracefossilsandshellyfossils.Eachrepresentsadistinctstageintheevolutionoflife.
Stromatolites Theoldersedimentaryrockscontainnoevidenceofanimallife.Onlyprimitive,largelysingle-celled,microscopicorganismslivedinthesea.Someofthese,beingphotosynthetic,wereresponsibleforgraduallybuildinguptheoxygencontentoftheatmospheretoapointwhereanimallifewasabletoevolveatsometimelateintheNeoproterozoicEra.
Nofossilsoftheancientmicro-organismsarepreservedintactinthepark,however,thereisabundantevidenceoftheiractivityinsomelimestoneunits,e.g.TrezonaFormation.Cyanobacteria(formerlyknownasblue-greenalgae)flourishedontheshallowseafloor.Matsformedbytheirintertwinedmicroscopicfilamentstrappedfinesedimentaryparticlessuspendedinthewaterandcausedchangesinwaterchemistry,duetophotosynthesis,whichallowedcalciumcarbonatetoprecipitate.Thisformedthinlimylayersand,asthematsgrew,theybuiltupthelaminatedstructuresknownasstromatolites.Dependingonthetypesofmicro-organismsinthematsandontheshapingeffectsofthelocalenvironment,stromatolitesmaytaketheformofwavylaminations,domes,cabbage-shapedstructures,
broadcolumns,orslender,branchingcolumnsandfingers.Examplesofthewavylaminated,dome-shapedandbroadlycolumnartypescanbeseenintheTrezonaFormation.
The Ediacara Fauna AnimalfossilsfirstappearintheWonokaFormation,butbecomeabundantintheRawnsleyQuartzite.
Theseanimalsweresoftbodiedandarepreservedasimpressionsonquartzitebeds.KnowncollectivelyastheEdiacaraFauna,theyofferourfirstusefulglimpseofearlyanimalevolution.Theyaredominatedbycircularimpressionsuntilrecentlythoughttobeoffree-floatingjellyfish.However,mostofthecircularformsaremorelikelytobeburiedanchoringdevices(orbulbs)offrond-likeanimals.
Stromatolites in the Trezona Formation. (Photo 042161)
Wilkawillina Gorge. Reddish Bonney Sandstone overlain by lighter Rawnsley Quartzite and darker Wilkawillina Limestone on the ridge. (photo 042160)
CAINOZOIC Quaternary
Tertiary Neogene
MESOZOIC
Palaeogene
Cretaceous
Jurassic
Triassic
PALAEOZOIC
Permian
Carboniferous Pennsylvanian Silesian
Mississippian Dinantian
Devonian
Silurian
Ordovician
Cambrian
NEOPROTEROZOIC NeoproterozoicIII
Cryogenian
Tonian
MESOPROTEROZOIC
Stenian
Ectasian
Calymmian
PALAEOPROTEROZOIC Statherian
Orosirian
Rhyacian
Siderian
ARCHAEAN
1.6
23
65
141
205
251
298
354
410
434
490
545
1000
1600
2500
GeologicaltimescalerepresentedintheFlindersRanges
Era Period Millionsofyearsago
Worm burrows in the Parachilna Formation. (photo 042163)
Mawsonites, an Ediacara fossil (x 0.4).(photo 038763)
Archaeocyaths in the Wilkawillina Limestone, Brachina Gorge (x 0.6). (photo 038766)
Dickinsoniacostata in the Ediacara Member, Rawnsley Quartzite, Brachina Gorge (x 0.7). (Photo 042162)
Trilobite from the Oraparinna Shale. (Courtesy of Jim Gehling; photo 408458)
Wilkawillina Gorge(11.4 km one-way)
TherocksalongthiswalkaresimilartothoseexposedalongBrachinaGorgebutthesequencedipsintheoppositedirection(east)asitisontheothersideofabroaddomalfold(anticline).AtWilkawillinaGorge,agraben(fault-boundeddepression)developedwithintheAdelaideGeosynclineasitwasfillingwithsediment.Foldingofthesedimentsinthegeosynclineabout500millionyearsagocausedthegrabentobetippedontoitsendsothat,fromabove,itssedimentscanbeseeninsection.
ThewalkbeginsinBrachinaFormationsiltstoneandABCRangeQuartzitebeforecrossingthesedimentaryrocksboundedbyfaultsofthegraben.ThesequencewithinthegrabenincludeslimestoneandsiltstoneoftheWonokaFormation,BonneySandstoneandWilkawillinaLimestone.AhighlightofthegorgesectionistheoutcropsofWilkawillinaLimestonecontainingexcellentexamplesoffossilsofthecoral-likearchaeocyatha.
Unlikethewesternpartoftheranges,theeasternrangescontainlittleRawnsleyQuartzite.AftertheRawnsleysandsweredeposited,mostofthetoplayersintheeastwereremovedbyerosionbeforetheCambrianlimestoneswerelaiddown.TheWilkawillinaLimestoneinthisareathereforeoverliestheBonneySandstoneandnot
theRawnsleyQuartziteasinthewesternranges.
Bunyeroo and Wilcolo Creeks (9.2 km return)ThisloopwalkthroughrollinghillsoftheBunyerooValleycommencesonBrachinaFormationsiltstoneandsandstonewhichdisplayripple-markedsurfacesindicativeoftheshallow-wateroriginofthisformation.ThewalktraversestheABCRange(ABCRangeQuartzite)andreddishBunyerooFormationshale.
Haywards Huts Yuluna (8 km loop), Trezona (8.2 km loop) and Aroona to Youngoona (15 km one-way)
Therearethreewalkstochoosefrom:twoloopsofabout8kmateitherendofaone-waywalkof15.4km.AttheAroonaValleyend,thewalkpassesthroughtheABCRange(ABCRangeQuartzite)whichshowslayersofsediment,ripplemarks,jointsandfolds.Attheotherend,thewalkpassesthroughtheTrezonaRange(TrezonaFormationlimestoneandshale)wheredome-shapedstromatolitesexposedinEnoramaCreekprovideevidenceofearlylifeonEarth.TilliteoftheElatinaFormation,depositedduringaperiodofglaciation,isexposedinEtinaCreek.ThebroadbandofcountrybetweentheABCandTrezonaRangesisoccupiedbysoft
BrachinaFormationsiltstonewhichgivesrisetoalandscapeoflow,rollinghills.
St Mary PeakDirect route (14.6 km return) Loop route (21.5 km return)
Thispeak,composedofRawnsleyQuartzite,providesviewsofthebasinofWilpenaPoundtothesouthand,tothenorth,rowsofrangesstretchingtothehorizon.
Bridle Gap(18.8 km return)
ThiswalkacrossWilpenaPoundwhichcanbestartedeitheratWilpenaChaletorBlackGapinMoralanaValley(outsideoftheNationalPark).ThetrailfromtheChaletviaPoundGaptraversestheredBonneySandstoneandoverlyingwhiteRawnsleyQuartzite.Aftertheruinoftheoldhomestead,thecentralpartofthePoundisfilledmainlywithrecentalluvium.
Heysen Trail(1500 km)TheHeysenTrailpassesthroughsomeofSouthAustralia’smostdiverseandbreathtakinglandscapes,traversingcoastalareas,nativebushland,ruggedgorges,pineforestsandvineyards,aswellasrichfarmlandandhistorictowns.Itincludesnationalparks,stateforestsandinternationallyacclaimedtouristdestinations–theBarossaValleyandthestunningWilpenaPound.
Hawker to Blinman RoadArkaroo Rock ArkarooRockisalargefallenboulderofsandstoneshedduringtheerosionofWilpenaPound.AcavecontainingAboriginalrockartwasformedbyfrettingofsandstonethroughtheactionofmoisture.
Rawnsley Bluff Lookout (Just south of the park boundary)
ThislookoutprovidesanexcellentviewofthesouthernendofWilpenaPound.WhiteRawnsleyQuartziteformsthehighpeaksoftherimofthesynclinalstructure.Belowthecliffs,theslopesareformedofredBonneySandstonewhichoverlieslightcolouredWonokaFormation.
Onenteringthepark,theroadfollowsredshaleoftheBunyerooFormationfor10km.About0.5kmaftertheWilpenaChaletturnoff,theroadpassesthroughagapintheABCRange(ABCRangeQuartzitewhichdipstothewest).Forthenext10km,theroadpassesthroughprogressivelyoldersedimentaryrocksincludingthinpinkdolomiteoftheNuccaleenaFormation,reddishsandstoneoftheElatinaFormationandgreylimestoneoftheTrezonaFormation.
Hucks Lookout Thislookout,locatedongreysiltstoneoftheTapleyHillFormation,
providesexcellentviewsofWilpenaPoundandthecompletewest-dippinggeologicalsuccessionfromTapleyHillFormationtoRawnsleyQuartzite.
Stokes Hill Lookout Thislookout,alsoonTapleyHillFormation,providesviewstowardsWilpenaPoundtothesouthwestandOraparinnaDiapirtothenorth.
Forthenext12km,theroadpassessubduedoutcropofmainlyshallow-dippingTapleyHillFormation.AfterOraparinnaStation,theroaddescendsthroughstratawhichdipgentlynorthwestandbecomeprogressivelyyoungerforthenext7km.TheseincludeflaggydolomiteoftheWockerawirraDolomiteMemberandcraggyoutcropsoflimestoneoftheEtinaFormation.AftertheBrachinaGorgeturnoff,
greenEnoramaShaleistraversedforabout10kmuntilthenorthernboundaryoftheparkisreached;alongthewesternsideoftheroadisthedistinctiveTrezonaRangecomprisedofalternatingbedsoflimestoneandsiltstoneoftheTrezonaFormation.
TheroadinthisareaisalsoattheclosestpointtotheEnoramaDiapirwhichispoorlyexposedonalowridge500mtotheeast,about1kmnorthoftheparkboundary.HeredolomiteoftheEtinaFormationoverliesmucholderbasaltraftedupbythediapir.
Great Wall of China Locatedsome7kmnorthofthepark,thisfeatureistheerodedcliff-edgeofaresistanthorizontalbedoflimestonewithintheEtinaFormation.
Brachina Gorge(18 km one-way) Thisdrive,whichstartsattheturnoffontheHawker-BlinmanRoad,containsfamouslandmarksinEarthhistory.TheroutecutsthroughrocksoftheAdelaideGeosynclinewhichrangeinagefrom650millionto520millionyears,andexhibitsoneofthemostcompletesedimentaryrecordsintheworldforthisage.Theserocksprovideauniquerecordofthegeologicaleventsandclimaticconditionsprevalentatthetimetheyweredeposited.Theyarethewesternremnantofalargedomalfoldandbecomeprogressivelyyoungertothewest,includingthesequencefromEnoramaShaletoWirrealpaLimestone.
SheltersateitherendofthedriveprovidegeneralinformationonthegeologyofBrachinaGorge.Stopsalongthewayinterpretfeaturesofinterestincluding:•stromatolitesintheTrezonaFormation,representingsomeoftheearliestlifeonEarth
•evidenceofaniceageintheElatinaFormation
•evidenceintheBunyerooFormationofameteoriteimpact600millionyearsago
•fossilsoftheEdiacaraFauna,amongsttheoldestknownsoft-bodiedanimals,intheRawnsleyQuartzite
•thefirstanimalswithskeletonsandshellsintheWilkawillinaandWirrealpaLimestones.
A more detailed brochure on the Brachina Gorge Geological Trail is available from PIRSA.
Wilkawillina Gorge Road AfterleavingtheturnoffontheHawker-BlinmanRoad,theroadcrossessubduedrollinghillscomposedofTapleyHillFormationsiltstone.About5kmaftertheturnoffisafaultedcontactbetweentheTapleyHillFormationandbrokenanddistortedrocksoftheOraparinnaDiapir.Outcropofdiapiricbrecciacontainingraftsofsedimentaryrocksandboulderybasaltoccursalongtheroadsideforthenextfewkilometres.MountCaernarvonintheLovesMineRangecanbeseenontheeasternhorizon.About2kmpasttheturnofftoWilkawillinaGorge,theroadturnseastwardalongabroadvalleyofBunyerooFormationshale.TothenortharethespectaculartreelesshillsoftheWonokaFormation,whiletheABCRangeQuartziteformsthesouthernwallsofthevalley.
Bunyeroo Valley(27 km one-way) OnleavingtheBunyerooValleyturnoff,theroadpassesthroughopencountryonshaleandlimestoneoftheTrezonaFormationforadistanceof13km.AfterYanyannaHut,theroadtraversesyoungerrocksuntilreachingBunyerooValleyLookout.
Bunyeroo Valley Lookout ThislookoutislocatedonsiltstoneoftheBrachinaFormationandprovidessweepingsoutherlyviewsalongthevalleyofBunyerooCreektowardsWilpenaPound.Aselsewhere,therimofthepoundiscomposedofwhiteRawnsleyQuartziteunderlainbyredBonneySandstone.TheroadthenfollowsBunyerooCreekthroughtheABCRangeandturnsnorth,traversingpurplishshaleoftheBunyerooFormation.
Drives Hikes
Rawnsley Bluff at the southern end of Wilpena Pound. Cliff-forming Rawnsley Quartzite overlies Bonney Sandstone. (Photo 042164)
Northern rim of Wilpena Pound from Bunyeroo Valley lookout, showing light coloured Rawnsley Quartzite overlying red Bonney Sandstone. (Photo 042165)
(Cover image courtesy of SA Tourism Commission; photo 043528)
©GovernmentofSouthAustralia
Firstpublished1994
Reprintedwithadditions2011
cont.
Location of hikes in the Flinders R anges National Park