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GEOLOGICAL SITES IN BRISBANE

NOMINATIONS FOR

THE BRISBANE CONSERVATION ATLAS

prepared by W.F. Willmott

GEOLOGICAL SOCIETY OF AUSTRALIA INCORPORATED Queensland Division February 1984

CONTENTS Page INTRODUCTION

THE ROCKS OF BRISBANE - BRIEF OUTLINE

NOMINATIONS OF SITES THE OLD MET ASEDIMENTS

Folded cherts at Mount Gravatt

Intense! y folded rocks, Macquarie Street, New Farm

Other exposures of the old metasediments

ENOGGERA GRANITE 3.

Contact between Enoggera Granite and surrounding rocks, Bardon

Part of old Ashgrove Quarry

BRISBANE TUFF 5.

Faulted unconformity between Brisbane Tuff and NeranleighF ernvale beds at reservoir near Maundrell Terr ace, West Chermside

- 17

Unconformity in quarry at Lutwyche Road, Windsor

Unconformity in Kitchener Road, Chermside

Welded tuff and pseudo-dyke at Kangaroo Point

IPSWICH COAL MEASURES 9.

,Coal-bearing sediments, Pentex Street, Salisbury

10. Mount Crosby fossil insect locality

11. Old basalt quarry at Moggill

WOOGAROO SUB-GROUP 12. Deformed sedimentary rocks, Allpass Parade, Shorncliffe

13. Unconformity between Woogaroo Sub-Group and NeranleighFernvale beds, Dellwood Street, Nathan

14. Unconformity ·between Woogaroo Sub-Group and NeranleighFernvale beds, Griffith University

LANDSBOROUGH SANDSTONE 15. Cross-bedded sandstone in old quarry at Brighton TERTIARY SEDIMENTS

40 43

QUATERNARY SEDIMENTS 16. High sand dune complexes, Moreton Island

17. High-level beach rock, St Helena Island

WEATHERING PHENOMENA 18. Laterite profile at Queens Road, Nudgee

UNUSUAL PHENOMENA 19. Mudsprings at Aspley

20. Cave eroded in colluvial valley fill Mount Gravatt

APPENDIX OF OTHER SITES

INTRODUCTION the Lord Mayo r of Brisb ane of This subm issio n resul ts from an invit ation from ty of Aust ralia to subm it nomi natio ns for the 14th Dece mber 1983 , for the Geol ogica l Socie whic h is to recor d the City' s most highl y the forth comi ng Brisb ane Cons ervat ion Atlas , inter ested in the prote ction of inter estin g value d natur al asset s. The Socie ty has long been welc omes this oppo rtuni ty of havin g these and impo rtant geolo gical featu res in the City, and in Coun cil decis ion-m aking proce sses. offic ially recor ded, and subse quen tly recog nised Background to the Socie ty's Inter est

that the key elem ents of the The Geol ogica l Socie ty of Aust ralia is conc erned rved for the futur e, just as bi~lo gical geolo gical herit age of Aust ralia shoul d be prese coun try's fauna and vege tatio n. scien tists wish to see adeq uate prese rvati on of the , inclu ding: Such geolo gical elem ents are of a varie ty of types assis ted the unde rstan ding of sites of high scien tific impo rtanc e whic h have i) natio nal level , and to whic h geolo gical histo ry, at a State , natio nal or inter refer ence may be need ed in the futur e. a. ii) exam ples of uniqu e or rare geolo gical phen omen sses whic h are conv enien tly iii) illus tratio ns of geolo gical featu res and proce both secon dary and tertia ry situa ted to aid the teach ing of the scien ce at level . cape s whic h are of aesth etic, iv) large scale phys iogra phic featu res or lands publi c. educ ation al and recre ation al value to the gene ral whic h neve rthel ess illus trate the v) rock expo sures of lesse r scien tific inter est gene ral publi c inter ested in local geolo gical fram ewor k to mem bers of the natur al histo ry. Geol ogica l Monu ment s Sub- Com mitte es of Over the last deca de, the Socie ty, throu gh its ing such featu res, assis ted cons idera bly State Divis ions, has been ident ifyin g and docu ment Natio nal Esta te prog ramm e. Most of the by a numb er of gran ts unde r the Com monw ealth ed, but only spora dic work has yet been more impo rtant featu res have now been docu ment carri ed out on the type v) featu res. so adva nced , with Gove rnme nt Actu al prote ction of ident ified featu res is not elsew here, such as in the Unite d King dom, recog nitio n fallin g far short of that occu rring Scien tific Inter est provi des prote ction for wher e an exten sive netw ork of Sites of Spec ial This is espec ially the case in Quee nslan d, impo rtant scien tific and educ ation al featu res. rnme nt have faile d to elici t any mean ingfu l wher e repea ted subm issio ns to the State Gove res coinc ide with areas alrea dy being respo nse, exce pt in cases wher e geolo gical featu for other reaso ns. consi dered for Natio nal or Envi ronm ental Park s draw the atten tion of autho rities Loca lly in Brisb ane also it has been diffic ult to occu rred with the build ing of a facto ry in a to the loss of impo rtant geolo gical sites , such as ples of dinos aur footp rints . quarr y at Albio n, wher e there were exce llent exam ntly welc omes the invit ation to The Quee nslan d Divis ion of the Socie ty cons eque Atlas , and hope s this will give offic ial inclu de geolo gical featu res in the Cons ervat ion , to the impo rtant sites withi n the City. recog nitio n, and even tuall y some form of prote ction Geol ogica l Feat ures in Brisb ane

ane are main ly smal l sites The featu res ident ified by the Socie ty in Brisb . and tertia ry stude nts, altho ugh one, the impo rtant for their teach ing value for secon dary tific resea rch, and anoth er, the high- level Moun t Crosb y fossil insec t site, has value for scien docu ment a previ ous highe r sea level . The b~ac h on St Hele na Islan d, allow s scien tists to r lands cape featu re of inter est for its high- dune comp lex on More ton Islan d is a large

2. our e. Most of the featu res were docu men ted in educ ation al, aest hetic , and recr eatio nal valu been have h t Quee nslan d", copi es of whic 1981 book let "Geo logic al Sites in Sout heas forw arde d prev iousl y to Coun cil. asing ly conc erne d abou t the grad ual In rece nt year s the Soci ety has beco me incre and City , caus ed by vario us rede velo pme nts rred loss of suita ble teach ing sites with in the occu has This ries. cutti ngs and old quar cove rings over of rock expo sures , such as road ce at seco ndar y leve l, coup led with the scien the of at a time of incre asing teac hing lude s teach ing excu rsion s furth er afiel d. For esca latin g cost of bus trans port , whic h prec ation of rema ining featu res in the City in the this reaso n the Soci ety feels that the iden tific Atla s will com e none too soon . a few exce ption s, a reaso nabl e The featu res nom inate d also prov ide, with ned d be used in any exte nsio n prog ramm e desig illus trati on of the rock s of the City , and coul , ever How ry. d in this aspe ct of natu ral histo for mem bers of the gene ral publ ic inter este to , sites a extr nece ssary to iden tify some addi tiona l inve stiga tion woul d prob ably be for nate exam ples more conv enie ntly situa ted supp leme nt the netw ork, or to prov ide alter a such if cts t the Coun cil furth er on thes e aspe publ ic acce ss. The Soci ety is willi ng to assis a on ing work st Park Auth ority is curr ently prog ramm e is desir ed. The Bris bane Fore the by sted (assi s on the rock s of this Park prog ramm e of leafl ets, displ ays, and signb oard s are not repr esen tativ e of the city as a rock e Geol ogic al Surv ey of Quee nslan d) but thes whol e. ty of sites . Man y are on Coun cilThe featu res nom inate d occu r on a varie has ld be relat ively easy to prot ect (the Soci ety cont rolle d Rese rves or othe r land s, and shou such of rding the prot ectio n and signp ostin g alrea dy corre spon ded with the Coun cil rega ). Som e occu r in road cutti ngs; these also featu res, see our subm issio n of Febr uary 1983 or re-ex cava tion of the cutti ng is likel y to shou ld be relat ively secu re, as any wide ning , and inad verte nt cove ring over or land scap ing impr ove the expo sure s rath er than harm them n priv ate land do pres ent prob lems for prot ectio would be the only thre at. A few featu res on n Tow r unde n lve. A com bina tion of prot ectio and acce ss whic h will take some effo rt to reso owne rs seem s appr opri ate. Plan ning proc edur es and nego tiati on with land ent prob lems . By their natu re road Publ ic use and acce ss to some sites does pres with incre asing dens ity of traff ic it is beco ming cutti ngs are com mon ly good expo sures , but For this reaso n, large r grou ps of stud ents . dang erou s to use them parti cula rly for road s, and wher ever poss ible sites have been nom inati ons have been avoi ded on the busi est so h is alrea dy acce ssibl e, or could be mad e chos en in quie t situa tions on publ ic land whic ngs , it has not been poss ible to avoid road cutti with little effo rt by the Coun cil. How ever ing park and ning wide road ed res. Som e limit altog ethe r beca use of the rarit y of some featu te priva on sites to ss acce of es. The prob lems facil ities coul d allev iate the situa tion in plac ss acce ic publ ral gene ge arran to r be poss ible land have been men tione d abov e; it may neve ing grou ps with prior notif icati on may be teach for ss acce fully to some of thes e, but hope able to be nego tiate d. robu st and capa ble of cons idera ble Fort unat ely most of the sites nom inate d are by fossi l site, is it sugg ested that the site be usag e by visit ors. For only one, the Mou nt Cros ss. not publ icise d or mad e avai lable for publ ic acce Nom inati ons

a brief outli ne of the rock s of To set the nom inati ons in some pers pect ive, r inati ons are the'n arran ged unde r each majo Brisb ane is give n in the next secti on. The nom rock unit, in orde r of decr easin g age. re, and outli nes its sign ifica nce. The Each nom inati on brief ly desc ribes the featu n the site men tione d. Mea ns of futur e prot ectio land tenu re is given , and any prob lems with site t inati on for the Mou nt Cros by fossi l insec and man agem ent are sugg ested . The nom

3. as it is on land contro lled involve s an area outsid e of the City of Brisba ne but it is include d by the Brisba ne City Counc il. elemen ts, as Most of the nomin ations would fall into the catego ry of landsc ape on Moreto n x comple une set out in the Lord Mayor 's letter of 14th Decem ber. The high-d Island would be in the catego ry of a landsc ape system . discov ered in As additio nal featur es of geolog ical import ance are occasi onally the Atlas for in made on provisi be new excava tions and road cutting s, it is hoped there will . further nomin ations of geolog ical sites to be accept ed in the future Counci l in the It is empha sised that the Societ y will always be willing to assist for nomin ated res measu process ing of the nomin ations and in the formul ation of protec tive prepar ation of the in assist sites, either on a formal or inform al basis. We are also willing to any natura l history progra mmes involvi ng geolog ical matter s.

THE ROCKS OF BRISBANE - BRIEF OUTLINE , and this is The Brisba ne region has had a relativ ely comple x geolog ical history e of the Becaus ). Table reflect ed in the variety of rocks now expose d in the City (see comple xity, some descri ption is warran ted here. outcro p in two The oldest rocks are meta-s edime nts of Palaeo zoic age which now s. These rocks were northw esterly -trendi ng belts in the wester n and southe astern suburb contin ental shelf; some once sedime nts deposi ted in deep water off the edge of the They have subseq uently been compr essed, subma rine basalt lavas were interbe dded. them in hard, comple xly deform ed, slightl y metam orphos ed and uplifte d, so we now see into two units, the divided disturb ed strata that are steeply incline d. They have been e), arenite (or udston (metam Neranl eigh-F ernval e beds, consis ting of shale, argilli te Bunya Phyllit e, the and_ greywa cke), quartz ite (or chert), and greens tone (meta- basalt) , ly deform ed, finer-g rained consist ing of phyllit e. The latter i_s consid ered a more intense part of the sequen ce. bodies of The Brook field Volcan ics and Jollys Looko ut Andes ite are small Triassi c or Permia n volcan ic rocks which were erupte d onto the old metase dimen ts during of the City. times. They outcro p only in the D'Agu ilar Range on the wester n fringes d into the The Enogg era Granit e origina ted as a body of magma which was intrude n edge of the Austra lian metase dimen ts in the Triass ic period , at a time when the easter d rock now outcro ps over contin ent was finally stabili sing. The slowly -cooled , coarse -graine heated and recrys tallise d has it places In . Bardon an oval-sh aped area betwe en Keperr a and also occur, especi ally the surroun ding rocks to hornfe ls, and thin off-sho ots or dykes betwee n Bardon and Indoor oopilly . d in the Late The Brisba ne Tuff is a sequen ce of volcan ic rocks that were erupte ion of a coal format the saw that ence Triassi c period , at the start of a period of broad subsid (depos its tuff welded of sheets thick measu re basin, the Ipswic h Basin. Most strikin g are cliffs at the as such res exposu nt from ash clouds from violen t eruptio ns) which form resista ne Tuff Brisba the of rocks s, suburb Kanga roo Point. In severa l places in the northw estern termed are ns junctio such ts; dimen can be seen resting on the old Palaeo zoic metase unconf ormi ties. in late Triassi c The Ipswic h Coal Measu res were laid down in the Ipswic h Basin . develo ped, but seams coal cant signifi times. They were thicke st in the Ipswic h area where rocks such as soft of mainly t consis th ey did cover consid erable areas of Brisba ne. As they disinte grate res exposu ial artific sha~e, siltston e _a nd sandst one, they outcro p poorly , and area. ead ll-Anst Moggi rapidly . Basalt occurs at the base of the sequen ce in the

TABLE OF ROCK UNITS IN BRISBANE

Age (mi llio ns of yea rs ago )

Per iod

. Qua tern ary 2

Roc k uni t

Allu vium Coa stal sed ime nts Dun e san ds

Plio cen e >t i::i::

Mio cen e

Oli goc ene

8 i::i::

E-r

Eoc ene Pal aeo cen e

Oxl ey Gro up [ Pet rie For mat ion

Cre tace ous 145

210

Jur ass ic

Woo garo o Sub -gro up [La nds bor oug h San dsto ne

Tri ass ic

~Ip swi ch Coa l Mea sure s '~B risb ane Tuf f K-.E nog gera Gra nite Bro okf ield Vol can ics [ Jol ly's Loo kou t And esit e

CJ)

w ~

245

Per mia n 290 380

u 0 NI

430 4 60

Car bon ifer ous

w < ..J <

0..

Dev onia n '

Sil uri an Ord ovi cian

530 610

Cam bria n Pre cam bria n

[Ne ran leig h-F ern val e Bed s /Bu nya Phy llit e

5. by the much The Ipswic h Basin was succee ded in late Triass ic and Jurass ic times The Basin. ur Nambo the lent, larger Claren ce-Mo reton Basin and a northe rn equiva ne Brisba the of parts over lowerm ost sedime nts, the Wooga roo Sub Group, were deposi ted the and est, southw the to area, which formed a strait betwee n the main part of the basin and shale; being relativ ely Nambo ur Basin to the north. They were chiefly quartz sandst one City. Equiva lent rocks the resista nt to erosion they can be seen in many exposu res around termed the Landsb orough are area, on Bright of the Nambo ur Basin, expose d in the Sandst one. develo pment of During Tertia ry times, the Brisba ne and Ipswic h areas saw the Group in the Oxley the termed nts, severa l shallow deposi tional basins. The resulti ng sedime fine graine d and shales nes, mudsto south and the Petrie Forma tion in the north, are mainly uently now conseq and d, olidate They remain ed relativ ely soft and uncons sandsto nes. res cut into exposu ial artific few outcro p very poorly . As they form flat countr y, there are lavas are basalt Some . them, and those that have been made, disinte grate rapidly . better interbe dded with the sedime nts in places , but these outcro p little adjace nt to In Quater nary times uncons olidate d alluvia l deposi ts accum ulated beach and of variety a in d resulte stream s, and fluctua tions in sea level around Moreto n Bay Island. n Moreto estuari ne sedime nts in coasta l areas, and high-d une sands on NOMINATIONS OF SITES of the variou s There are. of course numer ous outcro ps and artific ial exposu re~ t, or are interes of be rock units around Brisba ne, but many are too decom posed to numbe r erable consid a Nevert heless , there are still unrepr esenta tive of their units. units. the providi ng reason ably repres entativ e examp les of the rocks in the Atlas, the As it would be imprac tical and unreal istic to includ e all of these in examp les of e entativ nomina tions submi tted here concen trate on particu larly good, repres t. presen is e rock units, or on exposu res where some additio nal or unusua l featur (eg, SEB 8) The nomin ations are arrang ed accord ing to rock unit. Numbe rs given are the Geolog ical Societ y refere nce.

6. 1. FOLDE D CHERT S AT MOUNT GRAVA TT (SEB 34) (OLD MET ASEDIMENTS) Signific ance and value of This is an excelle nt exposur e of bedded chert, one of the commo n rock types ting illustra chert, the Neranle igh-F ernvale beds. The exposur e shows tight folding of the deform ation is the intensit y of deform ation that has affecte d the unit, and the way this and could be site g express ed in the relative ly hard cherts. The site is an importa nt teachin of some interes t to the general public.

Locatio n and access igh A road cutting on the access road to the summit of Mount Gravat t (Beenle 1:50 000 Sheet G.R. 071533) . See accomp anying map.

Geology (or The rocks forming Mount Gravat t consist almost entirely of bedded cherts accumu lations of quartzi tes) with only minor interbed ded siltston e. The cherts represe nt Carbon iferous siliceou s skeleto ns of radiola ria which collecte d on the deep sea floor in Early llised to a recrysta been have they rphism times. During deform ation, uplift and metamo quartzi te. ation The Mount Gravat t rocks have been affecte d by two phases of deform chevron both (folding ), of which the first is the most obvious . In the road cutting folds with of the style of and box-lik e profiles are present . The chevron folds in particu lar are typical west and strike deform ation in the bedded cherts. Their axial planes dip steeply to the ation. deform of phase first the of north-n orthwes t, which is charact eristic places Second -phase fold structu res are less obvious , and are only develop ed in axial dipping ly shallow have and open, are folds on Mount Gravat t. In the cherts such chert and shale dded interbe the In n. questio in planes. They are not obvious in the cutting phase of folding on the eastern side of Mount Gravat t a foliatio n associa ted with this second st. northea the to 30° to 20 dips and is apparen t in the rocks. It strikes about 330°

Land tenure is The road cutting is within the Mount Gravat t Recrea tion Reserv e R405 which vested in the Brisban e City Council as trustee .

Type of protect ion approp riate of The locatio n of the road cutting in the Recrea tion Reserve , under the control Council the g providin , present at te the Council , suggest s that protect ion should be adequa underta kes not to disturb it or cover it over.

Manage ment require ments It The road cutting of chert is quite resistan t to weathe ring and to hammer ing. . with care so road, winding the of eway is unfortu nately immedi ately beside the carriag ic density is not traffic by visitors is necessa ry; howeve r, visibilit y is reasona ble and tra ff opposit e side of the on present is area great e xcept on Sunday afterno ons. A small pull-off at, but it somewh d improve be could this the ro a d suitable for one or two cars (see photo) and ing connect road, the below tr"ack may be prefera bl/ to bring visitors to the site by a walking ~

7. with the proposed track to the nearby cave (see map and suggestions on Nomination 20 below). If such visitor development takes place, an information sign explaining the significance of the cutting would be appropriate.

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F aided cherts at Mount Gravatt

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Cherts at Mount Grava tt. Road cutting and small pull-of f area

Cherts at Mount Grava tt showin g folding

9. ET, 2. INTE NSEL Y FOLD ED ROCK S, MAC QUAR IE STRE 8) NEW FARM (SEB (OLD MET ASEDIMENTS) Signi fican ce and value

s of the inten se foldin g and This road cuttin g provi des one of the best illust ration (the Neran leigh -F ernva le beds and defor matio n that has affec ted the meta sedim entar y rocks of Brisb ane. These rocks have been the Buny a Phyll i te) which under lie much of the City in this expos ure evide nce of two such affec ted by more than one episo de of foldin g, and impo rtanc e for resea rch and teach ing phase s can be seen. It is thus of consi derab le purpo ses. Locat ion and acces s Stree t, New Farm , The road cuttin g is on the weste rn side of Macq uarie 04862 7). the old Dalge ty's Whar f (Brisb ane 1:50 000 Sheet G.R.

oppos ite

Geolo gy

fine-g raine d sands tone The rocks in the expos ure are shale , siltst one and minor consi derab ly by the ed chang been has of the Neran leigh -F ernva le beds. Their appea rance defor matio nal event s and by weath ering . (a plana r featu re cause d by The outcr op is domi nated by a prom inent foliat ion lel to the axial plane s of paral oped recry stalli sation of miner als under press ure) which devel ely north -sout h and has a shallo w ximat appro secon d gener ation folds. This foliat ion strike s ation folds have wave lengt hs of 5 to dip of 10-25 ° to the west. Most of the secon d gener 50 cm, and inter- limb angle s of 20° to 40°. d gener ation folds is an The layer ing which is here seen folde d by the secon of foldin g. It is thoug ht this was earlie r foliat ion devel oped durin g the first gener ation in the metas edim ents in Brisb ane where origin ally steep ly dippin g, as is the case elsew here this earlie r foliat ion is the most prom inent . has show n that an earlie r Rece nt resea rch on the struc ture of the meta sedim ents clasit es" (rock s defor med by brittl e descr iption of the rocks in the cuttin g as "cata fractu ring, such as in fault zones ) to be incor rect. know n throu ghout Brisb ane, Othe r good expos ures of folde d metas edim ents are d be neede for resea rch in the futur e. but it is impra ctical to prote ct every area that may e,xam ples and to serve as a teach ing The New Farm site was selec ted as one of the best area. land tenur e

80 m long is on the road The road cuttin g, which is about 8 to 10 m high and Coun cil. It is backe d by a small strip reserv e and is thus under the contr ol of Brisb ane City of land resum ed by the Coun cil in 1921 (Lot B - see map). Type of prote ction appro priate

ane City Coun cil were to This site shoul d be adequ ately prote cted if the Brisb Coun cil in recen t corre spond ence with agree not to distur b or cover over the cuttin g. The to be affec ted by road works in the the Socie ty consi dered that the cliff is unlike ly forse eable futur e.

Management requir ement s ry and soft. Altho ugh The expos ure is quite weath ered, and in places is powde and hence make them relief in this has helped to pick out some of the struct ural featur es the featur es. Stude nt rate oblite more visible , exces sive handli ng of the rocks could rapidl y groups should be made aware of this. ered neces sary, at Erecti on of an inform ation sign at this locali ty is not consid the public , and studen t group s presen t, as it is in an indust rial area not much visited by er/lec turer. visitin g the site would norma lly be instru cted by their teach

Intens ely folded rocks, New Farm

Intens ely folded rocks, New Farm. Road cuttin g.

11. OTHER EXPOS URES OF THE OLD MET ASEDIM ENTS faulted unconfo rmity betwee n Brisban e Tuff and Neranle igh-Fer nvale beds at Reservo ir near Maundr ell Terrace , Cherms ide West (SEB 49) in this This feature is nomina ted and describ ed under the Brisban e Tuff later s and argillite , arenites cherty submiss ion (Nomin ation 5). Excelle nt exposur es of cherts, rocks the ation deform shales can be seen, and a large fold structu re illustra tes the type of have endured . Unconf ormity betwee n Woogar oo Sub Group and Neranle ighFernval e beds, Dellwo od Street, Nathan (SEB 37a) in This feature is nomina ted and describ ed under the Woogar oo Sub-Gro up later arenite and shale dded interbe finely this submiss ion (Nomin ation 13). Excelle nt exposur es of (greywa cke) of the Neranle igh-F ernvale beds are present .

►

12. NIT E AND SUR ROU NDI NG 3. CON T ACT BET WEE N ENO GGE RA GRA ROC KS, BAR DON (SEB 48)

Sign ifica nce and valu e

Grif fith Driv e belo w Mou nt Coo t-tha A serie s of road cutt ings on Sir Sam uel s, as well igne ous intru sion on the surr ound ing rock shows good exam ples of the effe cts of an the few gran itic rock s them selv es. This is one of as the actu al con tact (bou ndar y) of the its clar ity heas t Que ensl and, whic h com bine d with known expo sed gran itic cont acts in sout teac hing purp oses . and acce ssib ility , mak es it inva luab le for

Location and acce ss fiths Driv e, betw een its junc tion with The road cutt ings are on Sir Sam uel Grif Shee t rs on Mou nt Coo t-tha . (Sam ford 1:50 000 Simp sons Roa d, Bard on, and the TV towe G.R. 9576 21).

Geo logy In the lowe rmo st a ligh t-co lour ed dyke Thre e cutt ings are of inte rest (see map ). : Such seen pene trati ng wea ther ed Bun ya Phy llite or sill of daci te (or quar tz porp hry) can be sam e the to ted rela a Grn aite, and are prob ably dyke s are com mon arou nd the Eno gger intru sive acti vity . hard band ed horn fels can be seen . This In the seco nd cutt ing, dark grey to blac k rock s. tion of the Bun ya Phy llite by the gran itic the at has deve lope d by heat ing and recr ysta llisa ried quar are and ite nd the Eno gger a Gran Simi lar rock s occu r in seve ral plac es arou Mount Coo t-tha Qua rry of the Cou ncil. f can be seen . Hor nfel s of the Bun ya In the third cutt ing, the con tact itsel form s the and adam ellit e of the Eno gger a Gra nite Phyl lite is on the east ern, dow nhill side r it, the Nea . tact is shar p and slop es dow nhill more mas sive expo sure s uphi ll. The con simi lar te daci . At the toe of the cutt ing a dyke of adam ellit e is pegm atiti c (coa rse grai ned) ing both adam ellit e and horn fels. to that in the lowe r cutt ing can be seen cutt

Land tenu re road rese rve of Sir Sam uel Grif fiths The road cutt ings are pres uma bly on the ncil. ions 679 and 1102 of the Bris bane City Cou Driv e whic h here sepa rate s free hold port Bris bane Fore st Park . The area is with in that desi gnat ed as the

Type of prot ectio n appr opri ate cont rol of the Cou ncil sugg ests that The loca tion in road cutt ings unde r the distu rb prov iding the Cou ncil unde rtak es not to prot ectio n shou ld be adeq uate at pres ent, them or cove r them over .

Management requ irem ents by stud ents over the year s, with the The con tact expo sure has been heav ily used orily in , the cont act can still be seen satis fact resu lt it is som ewh at degr aded . How ever a time e com may the fore seea ble futu re. The re som e bloc ks whic h shou ld surv ive for xpos e re-e to y ssar side of the cutt ing may be nece how ever , whe n mino r re-e xcav a tion of the is not e atur e f the be done unde r supe rvisi on so that ~he feat ure. If need ed, this shou ld only inad vert ently obli tera ted.

13. Each of the road cuttings is close to the carriagew ay and care must be taken by y visitors if inspectin g the rocks close up. Although traffic flows on the road are relativel ely Fortunat heavy, the importan ce of the exposure s still warrants nominati on for the Atlas. each cutting is opposite a large pull-off area where there is adequate room for parking. The Brisbane Forest Park Authorit y has been notified of the cuttings and is may consideri ng erecting signboar ds for the public. If this is done, parking arrangem ents ne d to be more formalis ed. '

Granit e

Enoggera Granite contact, Bardon.

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Close up of contact; dark hornf els on right, light adamellite on left.

Lower cutting with dacite dyke cutting Bunya Phyllite

15. 4. PART OF OLD ASHGROVE QUARRY (SEB 4) (ENOGGERA GRANITE)

Significance and value A contact of the Enoggera Granite with hornfelsed Bunya Phyllite, on the higher benches at the southeast margin of this quarry,is the best exposed of granitic contacts in the Brisbane area. Although it is in a private quarry and not as accessible as the contact on Sir Samuel Griffith Drive (see previously), the adjacent granitic rocks contain features of additional interest, making the site still valuable for teaching programmes. Geology

The quarry is mostly in pink granitic rock (adamellite) of the Enoggera pluton, The adamellite contains xenoliths of grey granodiorite, close to its eastern margin. representative of the lower, more eroded, northwest part of the pluton, and has been intruded by narrow aplitic veins and larger dykes of grey-green altered porphyrite, containing pyrite. Deuteric minerals such as calcite and pyrite are common in vughs and veins in the adamellite and in the past some exceptionally fine specimens of the zeolite mineral laurnontite have been found. Black tourmaline occurs in radiating masses and in veins, and epidote, chlorite and the sulphide molybdenite have been recorded. The contact is an intricate one, with narrow granitic veins cutting sharply across the banding of the hornfels. Location and access Beside Waterworks Road between Ashgrove and The Gap (Samford 1:50 000 Sheet G.R. 966633). Land tenure

Owned and previously worked by Readymix (Qld) (now BMG Quarries) the quarry has not been used for several years as reserves of stone on land zoned for Extractive Industry are exhausted. It is understood the company is considering re-development of part of the land. Type of protection appropriate Access for student groups is possible at the moment with the approval of the company. If the site is redeveloped for other purposes it would be highly desirable to set aside a small part of the quarry where the contact is exposed, and access to it, in some form of public land, reserve or easement. This would not seem to be too problematical as the area of exposure is not likely to be suitable for building. Such requirements could possibly be incorporated in any future re-zoning approval. Further examination of the site and discussions with interested parties are necessary before its future can be decided. Management requirements

The establishment of any public land to protect the feature would have to be limited to areas where safety for the general public can be reasonably assured; possibly some use of fences might be necessary. If the quarry is to be rehabilitated in any redevelopment programme there would be no objection to trees planted to obscure the bench

16.

may faces, as long as the feature remains visible at close range. Grass, vines and shrubs from distance some be probably would site need to be removed locally at times. As the by areas frequent ed by the public, and most visitors would be students guided . required t teachers /lecturer s, an informat ive signboar d is probably no_

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17. 5. FAUL TED UNCO NFOR MITY BETW EEN BRISB ANE TUFF AND NERA NLEIG H-FER NV ALE BEDS AT RESER VOIR NEAR MAUN DRELL TERRA CE, CHERM SIDE WEST (SEB 49) Signifi cance and value ent exposu re of A vertica l excava ted face beside this reserv oir provid es an excell t, as well eviden clearly re the Palaeo zoic Neranl eigh-F ernval e beds, with a large fold structu excelle nt an Tuff; ne Brisba as the unconf ormity betwee n these rocks and the overly ing le of a examp clear very a examp le of a coarse tuff which occurs at the base of this unit; and older the t agains tuff the fault, or fractur e, which has cut the unconf ormity and thrown most the of one re is rnetase diment s. Althou gh only recent ly recogn ised, the exposu g site. illustra tive in Brisba ne, and it has except ional import ance as a teachin

Location and access reserv oir off The exposu re is a cutting on the south side of the concre te water ). It is on 008718 G.R. Sheet 000 Lawren ce Road, west of Maund rell Terrac e (Brisba ne 1:50 locked on be may but days, week Brisban e City Counc il land which is commo nly open on il if Counc the with ed arrang be weeken ds. Presum ably access for studen t groups could • advanc e warnin g were given.

Geology broadly bedded Most of the cut is in Neranl eigh-F ernval e beds. These consis t of te and shale toward s the cherts and cherty arenite s at the eastern end, with more argilli ely undistu rbed at the west. Beddin g can be seen (dippin g moder ately to the west) relativ but almost compl ete subeastern end but it is more disrup ted to the west. Here a large ent teachin g examp le of horizo ntal fold structu re is event (see photo); it provid es an excell also have future value to how intense ly the old metase dimen ts have been deform ed. It may in this area. researc hers in determ ining the sequen ce of deform ation of these rocks expose s the At the easter n end of the cut, a small side cut facing west ne Tuff; it can be seen not unconf ormity betwee n the metase dimen ts and the younge r Brisba The Brisba ne Tuff is ntal. horizo ly rought s far above the bitume n road surfac e and appear white and purple ning contai tuff, e massiv ely represe nted here by a pink-g rey coarse , relativ ly not welded . probab was and soft ely relativ is rock fragme nts up to about 1 cm in size. It ormity is unconf the at n positio its and ts, studen It provid es .an excell ent examp le of a tuff to that shows re exposu the cuts, acing west-f instruc tive. At the corner of the north- facing and ards downw faulted been have ) ormity the tuff (and the visible part of the unconf re fractu or fault The up). faulted been (altern atively the metase dimen ts to the west have the in g beddin the with units, two plane is clearly eviden t, and the juxtap osition of the rare in Brisba ne and it 'is a rnetase diment s cut off, is most strikin g. Such an examp le is most highly valuab le teachin g aid.

Land tenure The excava tion is on Brisba ne City Counc il land associ ated with the

reservo ir.

Type of protec tion approp riate

Being on Counc il land, protec tion of the site would seem adequa te, Counci l does not cover it over in any way.

provid ing the

18. Management requirements

The exposure is robust and would be under no danger from students or the public, and requires no maintenance. Presumably the Council would have little objection to organised groups of students being taken to the site, but it is uncertain whether it would care to allow general access to the public. There is no feasible way of separating the exposures from the reservoir, being so close (10-15 m).

Faulted unconformity, Lawrence Road reservoir, Maundrell Terrace, Chermside West.

19.

Lawrence Road reservoir site. Tuff of Brisbane Tuff on left faulted against bedded cherts and cherty argillites of Neranleig h-F ernvale beds on right. Relative movement was down to the left (east).

Lawrence Road reservoir site. Horizonta l fold structure in bedded cherts and argillites of Neranleigh -Fern vale beds.

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20. OR 6. UNCO NFOR MITY IN QUAR RY AT LUTW YCHE ROAD , WINDS (BRISB ANE TUFF)

(SEB l)

Signifi cance and value

ns betwee n the This exposu re is one of the best of severa l unconf ormab le junctio be seen in the suburb s of Palaeo zoic meta-s edime nts and Triassi c volcan ics and sedime nts to ormity - the unconf ormity Brisban e. It is a particu larly good examp le of an angula r unconf level upward s in a cliff ground from plane is visible at a steep angle for severa l metres it, varying from a few of side either on exposu re, and there is continu ous exposu re of strata southe rn (Triass ic) the on metres d hundre metres on the northe rn (Palae ozoic) side to over a site. g teachin le side, along the face of an old quarry . It is a valuab Locatio n and access

The Windso r. The quarry is on the wester n side of Lutwy che Road at the from and is best seen unconf ormity is visible in the northe rn end of the wester n face, Access cal sub-sta tion. broade ned footpa th to the north of the quarry , adjace nt to an electri by a derelic t fence and d blocke t presen at is ormity into the quarry to the foot of the unconf a warnin g sign (Brisba ne 1:50 000 Sheet G.R. 030659 ). Geolog y

with argillit es, The Palaeo zoic rocks are quartz ite and greyw acke interla yered the dip of the beds; e and travers ed by quartz veins. They belong to the Neranl eigh-F ernval ar edge lies irregul y slightl foliatio n is to the north at a moder ate angle. On their eroded and m thick at 2.5 about layer a breccia of fragme nts of similar metam orphic rocks making up a of the soil part lower -up this site. This is interp reted as a scree or perhap s just the broken beds of ng overlyi the and profile weathe red in Pre-La te Triassi c times. The brecci a, the Above age. ic Triass sedime nts, tuff and ignimb rite belong to the Brisba ne Tuff of Late cm 20-30 about layers, breccia there are severa l stratif ied beds of alterna ting soft and hard wind and water as reted thick, of tuff or tufface ous sedime nt, which have been interp ed. Above these the deposi ted. The hard ban_ds are ferrugi nous and may have been silicifi Ferrug inous joint fillings rock is more massiv e and grades up to ignimb rite (welde d tuff). southe rly at 20-25° , but occur in the latter, nearly perpen dicular to the beddin g which dips end of the quarry walls, appear s to flatten away from the uncqnf ormity . At the south d behind one of the column ar jointin g in a radial and somew hat irregul ar form is expose Counci l sheds. Land tenure

ed by two The area betwee n Lutwy che Road and the quarry wall is occupi the quarry and il, Counc City ne Reserv es (R 602 and R 2709) under the contro l of the Brisba used as a now is area quarry face is along an area origina lly set aside for a road. The old of the end rn northe the at Works depot. The broade ned footpa th adjace nt to the sub-st ation 602. R on quarry from where the unconf ormity can be viewed appear s to be Type of protec tion approp riate

the contro l of The locatio n of the unconf ormity in a disused quarry face under ng that the providi t, presen at te adequa the Counc il, sugges ts that protec tion should be of the site ement manag some er, Counci l will agree not to disturb it in the future. Howev . below) (see s Will be necess ar y to keep the feature visible to visitor

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21.

Managem ent requirem ents

Access to the unconfor mity (at the northern end of the western quarry face) is need theoretic ally prohibite d by an unsightly derelict wire fence about l m high which is in wire the of side southern the on is sign ed' of replacem ent. A 'Trespas ses Will Be Prosecut 2 m about cliff low a formerly slope, of change abrupt an of top the fence. The fence is at to planted been have high, recently made more gradual by infilling with soil in which trees some at within 2 m of the face. The nearest trees will obscure the view of the unconfor mity also future time when they grow higher. A large tree on the quarry face to the south will hide the feature in years to come. Although it is certainly desirable to hide the old face from Lutwych e Road, it is . felt this could be done while still keeping the unconfor mity visible from a shorter distance (as It is suggeste d therefor e that the old wire fence be replaced by security fencing western the at e downslop d doglegge be should this that and elsewher e around the quarry), of (face) end to exclude the foot of the unconfor mity from the works depot area (a move made be to have probably would cliff the to close slope in only several metres). The break to more gradual by either a pathway or steps. Two or three of the planted trees in the area face cliff the on tree large the and , removed be should be excluded from the works depot needs to be trimmed occasion ally. Being so accessib le from the footpath of Lutwych e Road a signboar d explainin g the feature to the public may be appropri ate. ,¼, 'I

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Lan d ten ure

end of old qua rry fac e. Un con for mi ty at nor the rn rig ht, sed ime nts and tuf fs of Ne ran lei gh- F ern val e bed s on lef t. No te der eli ct bou nda ry Bri sba ne Tu ff dip pin g to the bou nda ry of qua rry ..:c um -wo rks fen ce, and tre e pla nti ng on wn hig her ). It is sug ges ted dep ot. (Tr ees hav e sin ce gro dog -le gge d dow n to lef t to tha t new bou nda ry fen ce be a onf orm ity fro m foo tpa th- are allo w pub lic acc ess to unc so d ove tre es sho uld be rem (ne ar car ). Clo ses t shr ubs and unc onf orm ity is not obs cur ed.

23. 7. UNCONFOR MITY IN KITCHENER ROAD, CHER MS IDE (SEB 2) (BRISBANE TUFF)

Significance and value

This road cutting is another good example of the angular unconformity between the Palaeozoic metasedimen ts and the overlying Brisbane Tuff. In many respects it is similar to the Windsor Quarry unconformity , on a slightly smaller scale. However, it is still a useful teaching site, and should not be needlessly destroyed. Location and access

Corner of Kitchener and Webster Roads, Chermside (Brisbane 1:50 000 Sheet G.R. 018693). Geology

Folded Neranleigh-F ernvale beds, mainly argillite, are unconformab ly overlain by a variable thickness (15 cm-60 cm) of argillite breccia; this in turn is overlain by a hard, light-coloure d tuff (20 cm), soft white tuff (35 cm), hard, brown tuff (about 30 cm) and stratified tuff or variable thickness and showing some cross-beddin g (possibly a base-surge deposit associated with the overlying ignimbrite). Bryan and Jones recorded a fossil log in the beds above the 'hard, brown tuff'. Land tenure

All of the cutting is on the road reserve. Road closure applications by adjacent landowners are being processed by the City Council at present, but should not affect the cliff face. Type of protection appropriate

The exposure in the road cutting should be relatively secure providing the Council agrees not to undertake any works that would cover it over. Any road widening at the corner would affect the rock face, but would not necessarily interfere with the feature. However, and such widening should only be carried out under supervision after discussion. Management requirement s

Occasional clearing of grass and other vegetation at the base of the cliff may be needed. If the Windsor unconformity (SEB 1) is treated as suggested, there is probably no need for a signboard at this site.

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24.

Unco nform ity, Kitch ener Road , Cherm side.

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Neran leigh -Fern vale beds on left, and tuffs of the Brisb ane Tuff dippin g to the right.

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25. 8. WELDED TUFF AND PSEUDO-DY KE AT KANGAROO POINT (SEB 47) (BRISBANE TUFF) Significance and value The cliffs at Kangaroo Point show continuous thick exposure of relatively fresh, massive welded tuff, the major rock type of the Brisbane Tuff. At the northern end, a pseudo, or sedimentary dyke occurs in a zone of alteration, and may represent a former vent or site of escape of fumerole gases. Sedimentary dykes are uncommon features, this being the only one so far recorded from the Tuff. Being so accessible the rocks are of interest to the public as well as students, and the dyke provides an added item of teaching value. The welded tuff is also of historic interest, being a major building stone during the early days of the city. The history of quarrying at Kangaroo Point would also be interesting, but this has not been researched by the Society. Location and access

The cliff face fronts the Brisbane River, between Captain Cook Bridge and C. T. White Park, immediately below the Kangaroo Point Technical College. The location is accessible from South Brisbane via Dock Street and a road under the Captain Cook Bridge which leads to a newly developed recreation area along the base of the cliffs. The dyke is about 100 m from the entrance to a military establishmen t close to the northern end of the road (Brisbane 1:50 000 Sheet G.R. 033607). Geology

The material of which the cliffs are composed is chiefly ignimbrite or welded ash-flow tuff. Most of the cliff exposure is of relatively fresh material, showing horizontal layering of crushed pumice lenticles (eutaxitic texture) and some rock fragments derived from underlying Palaeozoic rocks (phyllite etc.). The altered area beside the dyke is more or less triangular, tapering upwards, on either side of the almost vertical dyke. The dyke itself narrows and pinches out near the top of the cliff; it may have been infilled with quartzose material derived from weathering and erosion of the tuff surface. Within 3050 cm on either side of the dyke, the eutaxitic structure is not present, i.e. the pumice fragments are not flattened, a rare occurrence. Curved, upward-conv erging joints can be seen in the altered tuff on the southern side of the dyke. Land tenure The cliJfs and dyke are shown on maps within Reserve R 272 which was under the control of the Department of Harbours and Marine for quarrying purposes. However, they are now within an area developed for recreation by the City Council; their current tenure is not known by the Society. Type of protection appropriate

Now being within an area administered by the Council for recreation, the exposures seem adequately protected, providing the Council does not cover them over in any Way, particularly the dyke, but this seems unlikely. Management requirement s

The -exposures are robust and in no danger fro m the public. maintenance is required.

Virtually no

27. 9. COAL BEARING SEDIMENTS, PENTEX STREET SALISBURY (SEB 36) (IPSWICH COAL MEASURES) Significance and value

This cutting on a hillside in an industrial estate provides an excellent fresh exposure of coal-bearing sedimentary rocks, and an illustration of a rapid change in conditions of sedimentation in the sequence. It is one of the few good exposures of the Ipswich Coal Measures in the Brisbane area. It is used as a teaching site, as other exposures of coal-bearing rocks in open cut mines at Ipswich are relatively inaccessible. Location and access

A cutting at the back of three allotments on the northwestern side of the Pentex Street, Salisbury industrial estate (Beenleigh 1:50 000 Sheet G.R. 032533). Accessible at present over the vacant allotment 817. Geology

The lowermost sediments exposed in the cutting comprise a sequence of thinly bedded, dark grey carbonaceous shale and siltstone, with minor coal bands 1.0 cm or less in thickness. Occasional interbeds of white claystone contain well-preserved plant fossils. These sediments were deposited in lakes and swamps, and belong to the Late Triassic Brassall Sub-Group of the Ipswich Coal Measures. In the Ipswich area, the coal seams in this unit are mined extensively but there are no seams of economic importance in the Brisbane region. Overlying this carbonaceous sequence is well-bedded white sandstone with minor pebble conglomerate and occasional shale lenses. These strata form part of the Woogaroo Sub-Group of the Bundamba Group and were laid down by rivers in Upper Triassic-Lower Jurassic times. The contact between the upper sandstone and the lower shale-siltstone sequence is a disconformity; the bedding both above and below the boundary is sub-horizontal. Land tenure

The face is at the back of allotments 814, 817 and 874 (see map). Despite several attempts to determine the ownership of the vacant allotment 817 via which access to the face is obtained, this has yet to be ascertained. It was advertised for sale during 1983. Type of protection appropriate

It is presumed that eventually a factory or warehouse will be built on allotment 817, mostly obscuring the face and preventing access. Purchase of the allotment to prevent this happening could be prohibitively expensive, and would still not guarantee the face itself, Which is mostly on the adjacent allotments 814 and 874 (where there are already buildings). The alternative would be to try to persuade the owners of allotment 817 to allow access to at least part of the face, and to refrain from damaging it. It is unlikely they Would allow access around the back of any proposed building, but it may be possible to leave a small corridor . on the side boundary with allotment 874 to the east, fenced on both sides for security to the landowners. It may be possible for the City Counci l to negotiate this before any new factory is built.

28.

! ~anagement requirements If access can be arranged as discussed above, little management should be required. The face is relatively robust and should be able to cope with student visitation. An informative signboard for the public is not considered n·e cessary in this industrial area. I However, a sign indicating the nature of the access arrangements may be required.

Coal-bearing sediment, Pentex Street, Salisbury

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26. As the area has been opened to the public, a signboard explaining the origin of the welded tuff; the dyke, the historical significance as a building stone, and the history of quarrying would be appropriate. •

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29. 10. MOUNT CROSBY FOSSIL INSECT LOCALITY (SEB 12) (IPSWICH COAL MEASURES) Significance and value This is the best known of several localities in the Ipswich area where remains of fossil insects have been found in sediments of Triassic age. The localities are geological curiosities, as the preservation of fossil insect material is comparatively rare. They are of great importance for research and teaching purposes. As one site has already been lost to research (the Denmark Hill locality in Ipswich), it is important that the others remain available. Although the site is outside the City of Brisbane, it is nominated here because it is on land owned by the Brisbane City Council. Location and access

The main Mount Crosby site is in a cutting of the old Mount Crosby railway, which is now occupied by a water pipeline, at its crossing of the road from the Mount Crosby weir to Ipswich (Ipswich 1:50 000 Sheet G.R. 784523). It is easily accessible from that road. Other sites containing fossil insect material are known in the Mount Crosby area and one contains more abundant fossils, but this is on private land and has limited outcrop which could be depleted if visited by student parties. Geology

The insect-bearing rocks occur in the Late Triassic Mount Crosby Formation, which is a subdivision of the Kholo Sub-Group of the Ipswich Coal Measures. The sedimentary sequence in the pipeline cutting is almost horizontal. It consists of a lower conglomerate, of which 1.5-2.0 m is exposed, overlain by a 1.5 m thick, thinly bedded, quartzose sandstone with a ferruginous cement. The sandstone is overlain by several metres of finely bedded, greenish brown or green-grey siltstone. The siltstone is intersected by numerous fine cracks, and breaks readily into small fragments. The fossil-insect material is found in the siltstone beds. It consists mostly of insect wings 5-15 mm long in which veins and even pigmentation are well preserved. Thoracic and other parts of insects have also been found. Why the insect remains accumulated and were preserved in such prolific numbers is uncertain. The sediments in which they are found were probably deposited in quiet • lacustrine conditions. It has been suggested that water was banked up by wind on one side of the lake. This exposed mud banks on the other side, where insect material accumulated. Return of the water allowed further sediment deposition on the banks which buried the insect remains. Land tenure

The site is within an easement for the water pipeline, which is under the control of the Brisbane City Council. Type of protection appropriate

The pipeline easement is unlikely to be disturbed in the foreseeable future. The site should be adequately protected if the Brisbane City Council were to undertake not to disturb or cover over the exposure. Such an undertaking should not interfere with the Council's future use of the easement.

~ 54·157 ha

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Fossil insect locality , Mount Crosby . Scales 1 : 50 000 (abo ve) , 1 : 10 000 (below)

31.

Manage ment require ments

scenic The pipeline site is of no great interes t to the general public, as it has no digging and quality, and finding exampl es of the insect wings require s much patient would in fact be examin ation. The fossilif erous siltston e is natural ly very brittle, and not be publicis ed or eroded by excessi ve digging . It is thus suggest ed that the site genuine student s that so over, g signpos ted, but merely protect ed from acciden tal coverin effect on the ous deleteri and researc hers may still have access. Such access would have no adjacen t pipeline .

Fossil insect ,site beside pipeline on right.

32.

ll. OLD BASALT QUARRY AT MOGGILL (IPSWICH COAL MEASURES)

Significance and value The old Moggill Quarry provides good exposures of basalt lavas, which are not Vesicles and amygdules (gas bubbles) in the lavas are well represented in Brisbane. instructive for teaching purposes. Although not suitable for general public use, the quarry could be used in tours by student groups. Location and access The quarry is in the steep eastern bank of the Brisbane River at Anstead (formerly Moggill) (Ipswich 1:50 ODO Sheet G.R. 855528). It is accessible along a track leading off Hawkesbury Road. The track is presently locked at Hawkesbury Road. Access to the main old quarry would require a scamble down a steep hillside, but a newer upper face is easily accessible and provides adequate examples of the rocks.

Geology The quarry is in the Sugars Basalt, a local unit of basalt lavas and minor tuff and agglomerate at the base of the Ipswich Coal Measures, and hence of Triassic age. The lavas are greenish grey rather than the normal black, as they have been exten~ively altered to cholorite and other secondary minerals. On the newer, upper banch of the quarry, relatively massive basalt can be seen at the base of the face, but towards the top increasing proportions of vesicles and anygdules are present, culminating in a honeycomb rock at the surface which is interpreted as the top of a lava flow. Below the floor of the bench, the massive basalt gives way to a band of softer material. It is uncertain whether this is an altered or vesicular top to a lower flow or a band of tuff or agglomerate.

Land tenure The quarry is on freehold Portions 174 and 175 which are understood to be owned by the Brisbane City Council. A Council sign is at the locked entrance gate prohibiting vehicular entry. Type of protection appropriate It is unlikely that the quarry face will ever be obscured, and as further quarrying would only expose similar rocks, the site seems secure for the future. The only future consideration necessary would be to maintain an access corridor if the surrounding area is developed for closer settlement.

Management requirements Because of the dangers of the high face, unrestricted access to the general public is not desirable, and the access track should be kept locked as at present. However, it is hoped the Council would be sympathetic to requests for access to conducted student groups.

33.

34. 12. DEFOR MED SEDIM ENTAR Y ROCKS , ALLPA SS PARAD E, SHORN CLIFFE (SEB 7) (WOOG AROO SUB GROUP ) Signific ance and value

have The sea cliff and wave cut platform beneath Allpass Parade, Shorncl iffe providin g a long been used as a teachin g site for student s of geology in Brisban e. Besides e of a fault exampl an contain they age, ic cross section through sedime ntary rocks of Mesozo and evidenc e of associa ted deform ation. Locatio n and access

The cliff adjoins a small water-f ront park on the souther n side of Cabbag Headlan d, off Allpass Parade (Brisba ne 1:50 000 Sheet G.R. 085769) .

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Geolog y

the The sedime nts at Shorncl iffe occur in the area where the sequenc e of is there and Basin, r Nambou ly-aged Clarenc e-More ton Basin merges with that of the similar Sub oo Woogar the to d assigne ly debate as to which termino logy to use. They are current age. Group (of the Clarenc e-More ton Basin); they are probabl y Late Triassic in to The lower part of the Shorncl iffe section consists of conglom erate and coarse older from derived phyllite and very coarse sandsto nes. The conglom erate contain s chert the base of the Palaeoz oic metase diment s. This suggest s that these beds are close to Mesozo ic sequenc e in this area. a lowThe conglom erates are separat ed from the upper parts of the sequenc e by ne sandsto white Two tide. angle fault which is best seen in the wave cut platform at low fault the above occur beds 1.5 to 3.0 m thick separat ed by 3 to 4.5 m of carbona ceous shales la, The shales contain abundan t plant remains , includin g Coniop teris delicatu plane. a. Dioroid ium lancifol ia, Neocal amites carreri, and Cladop hlebis concinn This sequenc e is followe d by alterna ting sandsto ne, shale and siltston e. beds vary in thickne ss, and have a broad pinch-a nd-swe ll appeara nce.

Most

The low-ang le fault has been interpr eted as a plane of sliding along a bedding particul arly well plane. Below this plane the beds are highly folded. This deform ation is lly local, essentia develop ed in the wave-c ut platform below the cliff. The folds appear to be feature s. lide and they and the fault have been interpr eted as soft-sed iment, gravita tional-s some and fault, Later regiona l deform ation produce d variatio ns in the strike and dip of the faulting along joint planes. Land tenure

The sea-clif f would appear to form part of a Recrea tion Reserve (R 1586) the control of the Brisban e City Council .

under

Type of protect ion approp riate

The location in a Recrea tional Reserve , under the control of the council, Council can be suggest s that protect ion should be adequa te at present , providin g the persuad ed to ag~ee not to disturb it or cover it over.

35.

Management requirements

The cliff has suffered a significant degree of abrasion from natural erosion and by people climbing up and down the rocks. In one section where the rocks are quite broken To ameliorate future and loose the Council has erected "Keep Out" warning signs. signs explaining that warning explanatory more and fences small of erection deterioration, scrambling on the cliff itself is dangerous may be advisable so as to channel people to safe and less destructive routes. Being so accessible in a sea-side park, the exposure has interest for the general public, and an informative signboard is recommended if the above rehabilitation works are undertaken. .:·,\M{ffJL~ool

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36. 13. UNCONFORMITY BETWEEN WOOGAROO SUB GROUP AND NERANLEIGHFERNV ALE BEDS, DELLWOOD STREET, NATHAN (SEB 37a) Significance and value

This site is the best of three exposures in the Nathan area where the unconformity between the Neranleigh-Fernvale beds and the overlying sediments of the Woogaroo Sub Group can be observed. The exposure of the unconformity (an angular break between different rock sequences) is probably the best example in Brisbane, but in addition these are extensive clear exposures of the metasediments of the Neranleigh-F ernvale beds, and various sedimentary rock types of the Woogaroo Sub Group showing good examples of bedding. Occurrence of these various features in close proximity make the site one of the most important teaching localities in Brisbane. Location and access

The site is a long road cutting on a southerly extension of Dellwood Street, behind Fairlawn Street (Beenleigh 1:50 000 Sheet G.R. 044528). Although this road is bitumen, it is not shown on road maps and has in the past been fenced off. However, it now appears commonly used by local people gaining access to bushland to the south. Geology

The lower, western part of the road cutting is in rocks of .the NeranleighFernvale beds. Excellent clear exposure of rhymically bedded shale and arenite (greywacke) are relatively undeformed, and show original sedimentary features, such as soft-sediment deformation. Such banded sediments are typical of deep water continental slope sequences and are a valuable illustration. The unconformity is a clearly visible line which is at an angle to the Neranleigh. F ernvale beds. The lowermost bed of the Woogaroo Sub Group is a coarse breccia consisting of angular blocks of chert and other rocks of the Neranleigh-F ernvale beds. It is succeeded by thin beds of sandstone and more breccia, several metres of siltstone and shale, and then a massive thick bed of sandstone and pebble conglomerate which can be seen outcropping around the hillside. The unconformity can also be seen further west in the high wall of an old quarry, now occupied by a warehouse of Mazda Australia. The Geological Society previously documented the unconformity in this area, but the recent construction of the warehouse and security fencing now makes access for student groups difficult, and this site is consequently not nominated here. The unconformity can, however, still be seen on a large scale in the quarry face when viewed from a distance, such as from lower Dellwood Street or Fairlawn Street. This vista (which is unlikely to be obscured or destroyed) forms a valuable adjunct to the teaching value of the Dellwood Street cutting. The third exposure of the unconformity is in the grounds of Griffith University. It is nominated below. Land tenure The road and cutting appear to be on the unsubdi vided area of Resub 2 of Sub 2 of Resub 2 of Sub 2 of Portion 384. The reason for the constructed but now derelict bitumen road in this area is confusing, and the ownership of the area has yet to be determined . tviuch of the road cutting is right on the boundary of Lot 2 of R.P. 110675 (Portion 392 ) which forms the grounds of Griffith University.

37.

Type of protection appropriate Although the site is on private land, there would seem to be little threat to its continued existence. If the area is subdivided further, the cutting is unlikely to be disturbed, as it is on the boundary of Griffith University and building above it would not be possible. Agreement with the developers would only be needed not to cover it over. If the land is to remain undeveloped, an agreement with the landowners to allow access to students and not to cover it over would be desirable. To allow such continued access for the longer term, the question of Council ownership of the constructed road and cutting could be examined.

Management requirements The cutting is robust and capable of use by the public without destruction. If it becomes Council property, minor tidying up of regrowth shrubs and an erection of an informative sign would be appropriate.

Unconformities, Dellwood Street, Nathan and Griffith University

Road cutting on extensi on Street, Dell wood of Nathan , with unconfo rmity on left.

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39. 14. UNCONFORMITY BETWEEN WOOGAROO SUB GROUP AND NERANLEIGHFERNVALE BEDS, GRIFFITH UNIVERSITY (SEB 37b) Significance and value

Although not as impressive as the exposure of the unconformity at Dellwood Street, Nathan, it is a clear example of such a feature, and it is valuable locally for the teaching of students from Griffith University. Location and access

The unconformity is exposed in a cutting on the northern side of the main ring road within Griffith University grounds (Beenleigh 1:50 ODO Sheet G.R. 053525). (See map in previous nomination). Geology

The Neranleigh-Fernvale beds in this locality consist chiefly of relatively undeformed bedded shale and siltstones, with a gentle to moderate dip to the east. The unconformity is only at a small angle to this (although still discernable) and tracing it is an informative exercise for students. The sediments of the Woogaroo Sub qroup immediately above the unconformity are chiefly siltstone and fine grained sandstone; typical coarser sandstones occur further to the east. Land tenure

The grounds of Griffith University. Type of protection appropriate

Protection would be adequate if the Griffith University authorities would agree not to cover over the cutting in the future. Management requirements

The exposure is relatively robust and can withstand public usage. _If agreement is reached not to cover over the cutting, only very occasional removal of re-growth shrubs would be necessary to keep the feature visible.

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40. QUA RRY AT BRIG HTO N 15. CRO SS-B EDD ED SAN DST ONE IN OLD (LAN DSB ORO UGH SAN DST ONE ) Sign ifica nce and valu e

ry prov ide good exam ples of cros sExpo sures of sand ston e in this shall ow quar r level s show indic ation s of a later ite (or deep bedd ing and zona l weat herin g, and the uppe ing site, parti cula rly for local scho ols. weat herin g) profi le. It is valu able as a teach Loca tion and acce ss

ue at Brig hton (Bris bane 1:50 000 The smal l shall ow quar ry fron ts West Aven y acce ssibl e from the stree t, it is curr ently Shee t G.R. 0568 13). It is unfe nced and easil disus ed and in a dere lict cond ition . Geol ogy

in the Nam bour Basi n (from Sand gate The Land sbor ough Sand ston e was laid down it early Jura ssic time s. In the Sand gate area to north of Nam bour ) in late Tria ssic to shale and with in mino r cong lome rate, silts tone cons ists pred omin antly of quar tz sand ston e sited in a high ener gy, braid ed river chan nel band s. It is inter pret ed as havin g been depo envi ronm ent. expo sed in the quar ry show s sets of The med ium to coar se grain ed sand ston e appe ars to be roug hly horiz onta l. A cros s bed cros s beds abou t 0.3 m thick . Norm al bedd ing of an of sedi men tatio n depo sits sand s off the end occu rs in a river envi ronm ent when a pulse the to es angl are cons eque ntly at cons idera ble adva ncin g sand bank ; the resu lting laye rs tly sligh with beds n build up a serie s of cross horiz onta l. Succ eedi ng pulse s of sedi men tatio ing bedd al ngui sh this type of bedd ing from norm vary ing orien tatio n. It is impo rtant to disti ple is a conv enie nt illus trati on for stud ents . in the study of sedi men tary rock s, and this exam g phen omen a, with swir ling and The sand ston es also displ ay zona l weat herin d throu ghou t the rock , inde pend ant of the conc entri c patte rns of brow n· band s deve lope g dic depo sitio n of iron oxid es from circu latin bedd ing. Thes e have been caus ed by the perio grou ndw aters . weak ly deve lope d later ite prof ile is In the nort hwe stern corn er of the quar ry a of an in hot hum id clim ates and gene rally cons ist pres ent. Late rite weat herin g prof iles form ed leach or d palli a into , zone gh a mott led uppe r iron- rich zone pass ing down ward s throu past clim ate cond ition s. In the quar ry a thin, zone . They are of inter est as a reco rd of over mott led and leach ed sand ston e, pass ing weak ly deve lope d iron -rich zone can be seen profi le is well deve lope d on the Land sbor ough ' down into unaf fecte d rock . This later ite used exam ples in the Brisb ane area whic h can be Sand stone furth er north , but there are few for teach ing purp oses . Land tenu re

and is appa rentl y vaca nt Crow n Land ; The land form s part of Port ion 43 and 43A n r the cont rol of the Land s Adm inist ratio a sign on site state s it is Crow n Land unde Com miss ion. Type of prot ectio n appr opri ate

pme nt for resid entia l or indu stria l The r:nain dang er to the site woul d be rede velo the shall owne ss of the e xcav ation . If thi s deve lopm ent, whic h woul d not be diffi cult given the a smal l area enco mpa ssing the expo sures of occu rred it woul d be desir able to exclu de

41. laterite profile, and representa tive examples of the cross bedding and weatherin g patterns. Such an area could be designated as a public park; it could encompass the need in any case to leave a buffer strip beside the adjacent arterial road leading to the Hornibroo k Highway. Manageme nt requireme nts

The rock features are robust and can tolerate public use. If an area is set aside to protect them, tidying up and developing the area as a small public park for local residents would be desirable. A signboard explaining the rocks would be appropriat e.

-Cross-be dded

42.

Old quarry at Brighton. Note laterite profile in r ight background.

Cross-bedde d sandstone, showing some zonal weathering rings at top.

43. TERTIARY SEDIMENTS Few exposures of these sediments and interbedded basalts are known within the city, on account of the low topography they form, and their softness, which leads to rapid None are consid·e red sufficiently striking to be deterioration of any artificial cuts. traces of Tertiary sediments can be seen in the although Atlas, the for nominated separately laterite weathering profile nominated at Nudgee (see later). Fossiliferous Tertiary sediments are known in clay pits in the Ipswich area, al though continued access to them is not assured.

16. HIGH SAND DUNE COMPLEXE S, MORETON ISLAND (SEA 2) (QUATERNA RY SEDIMENTS ) The giant dunes of this landscape system in the centre of Moreton Island are reputed to be amongst the highest sand dunes in the world. The Society has previously suggested that an adequate sample of the dunes should be protected for the future. The dunes are old vegetated structures which are though to have built up during former periods of strong blowing of the southeasterly winds, possibly at times of lower sea levels or rising sea levels. In the northern core of the island the dunes are probably Pleistocene, but in the southern half, old dunes have been reworked in the Holocene to give younger dunes. Mount Tempest, the highest point, consists of a Holocene dune over-riding an older Pleistocene dune. An adequate sample of the dunes will be protected in the expanded National Park announced for the island by the Queensland Government .

44. 17. HIGH- LEVEL BEACH ROCK , ST HELEN A ISLAN D (SEB 18) (QUA TERNA RY SEDIM ENTS) Signifi cance and value n Bay is quite A platfor m of expose d beach rock on this island in Moreto been dated. Additi onal signifi cant, as it is eviden ce of a former higher sea level which has in Moreto n Bay, and from eviden ce for this level comes from a dated coral on Peel Island carbon ate beachr ock is raised shell beds at Decep tion Bay to the north. Furthe rmore, res. uncom mon in southe at Queen sland, and St Helena has excelle nt exposu Locati on and access island at Grid The beachr ock outcro ps best along the southw estern beach of the 225699 . A G.R. at quarry Refere nce 225697 (Brisba ne 1:50 000 Sheet) and in a small disused comm ercial operat or runs a regula r boat servic e to the island. Geolog y Tertia ry basalt St Helena is an island of about 80 hectar es, and has a core of a sedime nt island the of part estern with a maxim um elevati on of 21 m. In the southw by two crossed is and core, basalt the platfor m with an elevati on of about 5 m laps onto sand the of arce appear ed degrad the degrad ed sand ridges. The height of this area and , second a island the of side n wester ridges indica te a probab le Pleisto cene age. Along the s lagoon swale and ridges beach ing lower platfor m of. Holoce ne sedime nts occurs , contain platfor m is compo sed of near the northe rn tip of the island. To the southw est this lower beach. the along and , quarry carbon ate beachr ock, which is expose d in a small basalt gravel, The beachr ock is compo sed princip ally of well-c ement ed are also distinc t bands presum ably derive d largely from the core of the island, but there deposi t is 2.6 m. A the of ess thickn d expose contain ing shell and coral debris. Maxim um obtain ed for a been has t) presen e (befor Holoce ne radioc arbon date of 2 540 + • 85 years level in late sea e relativ m +2 a and mollus c shell in the upper se·c tion of-the beachr ock, spring -tide below forms ly typical postgla cial times has been deduce d. Howev er, beachr ock outcro p of t highes the below m 1 high water mark, so mean sea level may be more than beachr ock the when level sea beachr ock which is active ly formin g at the time. Thus mean level. sea mean t presen above on St Helena was develo ping need only have been about 1 m Land tenure d by a recent ly Most of the island, includi ng the beachr ock exposu res, is covere gazett ed Nation al Park, which extend s to high water mark. Type of protec tion approp riate and Wildlif e Protec tion is now adequa te within the Nation al Park. Nation al Park Servic e staff have been made aware of the site. Manag ement requir ements consid erable As the beachr ock exposu res are quite robust , they could withst and al for the materi e provid to NPWS visitor usage. The small quarry may be reopen ed by the section better a expose may tions restora tion of histori c buildin gs on the island. The excava arise. to likely are ts throug h the beachr ock than is now visible , and no conflic to visitor s is An inform ative signbo ard explain ing the signifi cance of the site consid ered approp riate.

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47. 18. LA TE RITE PROF ILE AT QUEE NS ROAD , NUDG EE (WEA THER ING PHEN OMEN UM) Signif icance and value

few examp les of such A lateri te profil e expos ed in an old pit provid es one of the ry sedim ents, traces of which a profil e in the Brisba ne area. Here it is develo ped on Tertia le or an impre ssive site at examp can be seen at its base. Althou gh not an outsta nding d out, to act as a local carrie ever presen t, it could be impro ved, if redev elopm ent works are teachi ng site. Locat ion and acces s

G.R. 09572 5), was The site beside Queen s Road, Nudge e (Brisb ane 1:50 000 Sheet Narro w tracks lead down to the appar ently once an old quarry for lateri te road gravel s. and is cover ed with unsigh tly floor of the pit, which is now used as an illega l rubbis h dump, debris , car bodies , etc. Geolo gy

ry Petrie Forma tion, The Nudge e area is under lain by sedim ents of the Tertia te and interb edded basalt which which consis ts of mudst one, shale, sands tone, congl omera e the sedim ents have been were probab ly depos ited in a lake enviro nment . At Nudge and some low cuts into the upper laterit ised, as evide nced by red soils on the crests of rises hot humid clima tes and gener ally ferrug inous zone. Later ite weath ering profil es form in h a mottl ed zone, into a pallid or consis t of an upper iron-r ich zone passin g downw ards throug Plioce ne to Pleist ocene . be leache d zone. The age of this lateri te profil e is thoug ht to only the upper The slopin g face of the pit below the road mainl y shows and expos es the m) (3-4 r is deepe ferrug inous zone of the profil e, but at its northe rn end it mudst ones been have to appea r mottle d zone and traces of the origin al sedim ents. These is cover ed e profil the part of with bands of coarse congl omera te. Unfor tunate ly, the lower rance . appea which disgui ses its by a venee r of lateri te gravel fragm ents shed from above , Land tenur e

The site appea rs to be Brisba ne City Counc il land as Counc notify ing that dumpi ng is illega l (see map).

il signs are erecte d

Type of prote ction appro priate

il were to agree to If on Counc il land, protec tion would be adequ ate if the Counc ent of the unsigh tly area. retain the northe rn end of the face in any future redev elopm Mana gemen t sugge stions

be greatl y impro ved The appea rance and value for teachi ng of the profil e would would remai n free -ft zing, so that if a sectio n of the lower part could be steepe ned by bulldo of obtain ing means zing could be a from the ferrug inous grave l shed from above . Such bulldo site. the of of rehab iii tation fill for levell ing and cover ing of rubbis h in any progra mme

48.

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Laterite profile, Queens Road, Nudgee

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Cut face beside Queens Road, now illegal rubbish dump. Upper iron-rich zone visible at right, above white mottled zone. Pisolitic gravel from upper zone shedding down to Traces of original Tertiary obscure mottled zone. mudstone and conglomerat e gravel can be seen in mottled zone in remnant hump on left.

49. 19. MUDS PRING S AT ASPLE Y (SEB 9) Signifi cance and value .

, is an examp le of an An area of mudsp ring activit y at Graham Road, Aspley well as an import ant as public, the to t interes of is unusua l geolog ical phenom enon which forces its way to the teachin g site. Mudsp rings result - when artesia n underg round water into suspen sion. They are surfac e throug h clayey sedime nts which are soften ed and taken rare in southe ast Queen sland. Locati on and access

Street, Aspley The mudsp rings are at the corner of Graham Road and Hawbr idge (Brisba ne 1:50 000 Sheet G.R. Oll 741). Geolog y and history

consist s of The spring s occur in the Petrie Forma tion, of Tertia ry age, which ironsto ne and one sandst ne, siltsto mudsto ne, shale, basalt, limest one, oil shale, brown coal, Aspley h throug g trendin zone a for lenses . The strata are genera lly sub-ho rizonta l, except faults. g trendin esterly northw northalong Albany Creek, where dips of up to 60° are eviden t altered of t consis site the at strata Drillin g adjace nt to the mudsp rings indica tes the ed perme able ironsto ne mudsto ne, shale, sandy argilli te, and siltsto ne. A lens of fractur to 6 m, -and is presum ed 3.5 occurs adjace nt to arid possibl y below the springs , at depths of the apex of the fold with to be the aquife r (water bearin g layer). It may be slightl y folded below the springs . ed eastwa rd. The mudsp rings first develo ped about 1930. They gradua lly extend th of Hawbr idge Street In 1970 excava tion~ for a water main along the wester n footpa preven t this new site of to ary necess was encoun tered liquid mud, and later a retaini ng wall Hawbr idge Street for of ng wideni activit y from floodin g the street. In 1976, an attemp ted heavy machin ery, some of loss near an adjace nt subdiv ision reactiv ated the springs with the . The Brisba ne Street idge and in 1977 a small spring develo ped on the carriag e way of Hawbr to its presen t Street idge City Counc il then require d the re-rou ting of the end of Hawbr positio n. long by 7.5 m The active , east-w est trendin g zone of the springs is about 26 m formed by mound The wide at its wester n end; it narrow s to l m wide at the eastern end. the most year) dry a the mud accum ulation is up to 1.5 m high. In Septem ber 1980 (after former the on 1977 in out active site was at the eastern end, where the new activit y burst active older the of most carriag eway of Hawbr idge Street . A hard crust had formed over zones, althoug h they were obviou sly still soft at depth. r throug h At Aspley , it is presum ed that water enters the ironsto ne aquife The west. the to ground gravel ly and sandy layers in the Petrie Forma tion beneat h higher point, weak a at strata water under pressu re in the aquife r has soften ed the overlyi ng . The water with system fault Creek y -Alban Aspley the in ance possibl y a zone of disturb that of the hydros tatic clay in suspen sion has risen to build the mound s to a height near as rainfal l will affect the head. The level of mud in the springs will vary with the season , has been subdivi ded, they hydros tat ic balanc e. Now that the land to the west of the springs a se the hydros tatic head. could becom e more active , as wateri ng of garden s etc. could incre_ Land tenure

F ree hold land owned by t he Br isbane Cit y Counc il.

50.

Type of protection appropriate

In the 1960's there was an attempt at private commercial exploitation of the site for its curiosity value. In 1976 and 1977 when the surrounding land was being subdivided for housing, there were some suggestions that the mudspring area could also be built on , but the difficulties soon became obvious. Two blocks of the subdivision covering the springs were transferred to the Brisbane City Counc il for public purposes. It is considered that the springs are adequately protected under Council ownership, providing the Council will undertake not to interfere with them in the future. In fact, it is highly advisable to disturb the site as little as possible, as previous experience has shown that interference can cause new outbreaks. Management requirement s

With increasing settlement in the area it is important the springs should be fenced, as the soft mud surface looks deceptively hard, and a small child could get into difficulties if not supervised. Gates in the recently erected Council fence should be kept locked. The Council has erected a warning sign fronting Hawbridge Street; this should be maintained. A legacy of derelict concrete paths, lean-to sheds and weeds from the earlier attempt at commercial exploitation has recently been cleared by the Council. As the springs are of considerable interest to the public, occasional maintenance of grass and weeds within the enclosure and erection of an informative signboard is considered warranted.

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Close up of one of the active mud springs , 1980

52. 20. CAVE ERODED IN COLLUVI AL VALLEY FILL MOUNT GRAVA TT (SEB 46) Significan ce and value

This is an example of a cave in unconsolid ated colluvial debris, which has developed by piping, a process of removal of sediment particles by percolatin g groundwat er. Piping on the scale of this cave is unusual, and it is the largest example known in southeast Queenslan d. Being situated in the Mount Gravatt Reserve, the cave has potential as an item of interest to the public in any recreation al developme nt undertaken in the Reserve, as well as being a valuable illustratio n to students. Location and access

The cave is in the floor of a gully on the eastern flanks of Mount Gravatt. Access is gained from the road to the summit lookout by walking a short distance down the gully (see map) (Beenleigh 1:50 000 Sheet G.R. 075531). Geology

Mount Gravatt is composed predomina ntly of bedded cherts of the Neranleigh Being resistant to decompos ition, these have shed thick deposits of F ernvale beds. weatherin g debris, consisting of angular chert fragments in a silty clay matri x, into man y of the gullies in the mountain. The cave has developed by piping in such a deposit in the floor of one gully. Piping is a process of subterrane an erosion by percolatin g groundwa ter which disperses or floculates clay or removes fine particles into an open space or more open textured strata. It is common in alluv ium throughou t Queenslan d but rarely develops cav ities of any size. Insufficien t study .has been made of the Mount Gravatt cave to determine the exact mechanism by which the piping has occurred. It has about 60 m of passage and several entrances. After rain, water flowing down the gully enters the upstream entrances of t he cave and flows out the downstrea m entrance; this portion of the c ave is quite room y and floored with angular pebbles and cobbles of chert, except for a small outcrop of chert bedrock. A major side passage leads off near the downstrea m entr anc e , but it be comes ver y low and soon ends; the floor is composed of compacted ear th. The roof and walls throughou t the cave are of angular chert pebbles embedded in a cla y matri x. Land tenure The cave is within the Mount Gravatt Recreatio n Rese rve which ha s as trustee the Brisbane City Council. Its downstrea m entrance is probably very close to the eastern boundary of the Reserve, which is above backyards of houses front ing Stanley Street. Type of protection appropria te

The location in the Recreatio n Reserve is consid~red adeq uate protec t ion at pres ent, providing the Council rem ai ns aw are of the cave and undertake s not t o di st ur b it. Manageme nt requireme nts

The cave is at present in a derelict state, with much bro ke n glass and some other larg er debr is resul t in g fr om ac ti vi t ies of loc a l del inque nts, bu t relatively little e ffort is requi red to clean t his up.

53. Developmen t as a point of interest for the general public would require a short length of walking track from the Mount Gravatt road above; a suitably large pull-off area already exists at a convenient point on the road (see photo), this would only need to be formalised somewhat (and rubbish cleaned up). The track would best be taken to the lower cave entrance and into the large lower section where there is adequate head room. Although the cave roof is stable, it is possible knocking it could dislodge some chert fragments, and it is suggested that the public be discouraged from using the low inner sections of the cave. To this end, a small fence in the lower section with a sign drawing attention to the roof condition would be an adequate deterent. To safeguard long term stability, it would be best to avoid laying out the walking track above the roof of the cave itself, to minimise vibration from walkers feet. A suitable explanatory signboard is considered desirable at the cave entrance. The parking area for the start of the track is not a great distance from the folded cherts nominated earlier in this submission. Because of limited parking of exposure it may be preferable to designate parking all in this one area, with a walking there, facilities the contour of the hill to the folded chert site; this could be around leading track with the cave, and the whole development promoted as a circuit a into incorporated "Geological Walk".

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55. APPE NDIX OF OTHE R SITES this subm ission , sever al other Besid es the featu res nomi nated for the Atlas in teach ing or refer ence purpo ses. They expos ures aroun d Brisb ane are occas ional ly used for other sites, or are unsui table for use have not been nomi nated here becau se they dupli cate rous situat ions besid e busy roads . by stude nt group s or the public on accou nt of their dange ities that the Brisb ane City Sever al such sites are listed below as addit ional local icanc e, it still would be unfor tunat e if Coun cil shoul d be aware of. Altho ugh of lesser signif these were unnec essar ily destr oyed or cover ed over. le beds in a lower cuttin g Expo sure of fresh green stone of the Neran leigh -F ernva 1) ay. This is one of the few of the Mt Oman ey round about on the Cente nary Highw ane area; howe ver, it is Brisb the easily acces sible expos ures of green stone in . about right besid e the carria gewa y of the busy round 2)

ings along the Cente nary Expo sures of the Ipswi ch Coal Meas ures in cutt can be recog nised in these unit Highw ay. Vario us const ituen t forma tions of this use of the expos ures for safe cuttin gs, but again the highw ay is too busy to allow after the highw ay is ed amin re-ex group s. Neve rthele ss, the situat ion could be wide enoug h to be are gs conv erted to four lanes to see wheth er some cuttin safely used. ite in the cuttin g on Milto n Dyke penet rating defor med rocks of the Buny a Phyll A narro w footp ath and very Road south of the Auch enf lower shopp ing centr e. high traffi c flows make this a dange rous site. Vultu re Stree t besid e South Defo rmed rocks of the Buny a Phyll ite in cuttin g of med rocks nomin ated at defor the Brisb ane Town Hall. Some what simil ar to to advan ced stude nts of est Mainl y of inter Macq uarie Stree t, New Farm . struc tural geolo gy.