PAPERS AND PROCEE'DINGS OF THB ROYAL SOCIETY OF TASMANIA, VOLtlME 94 LOWER PALAEOZOIC UNCONFORMITIES IN SOUTH-WESTERN TASMANIA
By
B. SCOTT
Lyell-E.Z. Explorations*
(With 2 text flgllres).
IN'l'ItODlTCTION Jukesian Unconformiiy.-The Jukesian Uncon formity has been defined as the angular discordance Recent geological work in south-west Tasmania between the Dundas Group below and the Junee on a regional scale has allowed the compilation of Group above, as revealed at the northern end of existing information regarding Lower Palaeozoic Mt. Jukes, south of Queenstown. Stratigraphically unconformities, namely the description of new this unconformity may be considered as the localities and in some cases the amplification and erosional surface of the Dundas Group on which extension of previously described exposures. the
103 104 LOWER PALAEOZOIC UNCONFORMITIES IN S.W. TASMANIA
UNCONFORMITY .. BETWEEN .. JUNEE . GROUP TABLE I. AND PRE-DUNDAS GROUP ROCKS Lower Palaeozoic Stratigraphy a. Andrew River Area (Mather, 1953, p. 15) In this area the Dundas Group is absent and rocks correlated with the Owen Conglomerate, which is overlain by the Gordon Limestone, rest Gordon Limestone directly on the Precambrian (Fincham Group, see Florentine Valley Mudstone Table D. The actual contact between the Owen Caroline Creek Sandstone JUNEE GROUP Conglomerate and the Fincham Group has only Owen Conglomerate been observed in one stream section. In this section Jukes Breccia coarse grained Owen Conglomerate overlies a pink ish coloured quartz schist of the Fincham Group. The rocks on either side of the boundary have com DUNDAS GROUP parable attitudes. Along the regional strike to the north-west at about 1200 feet distant part of the Precambrian Stratigraphy-Frenchman's Cap Area base of the Owen Conglomerate is exposed. It con sists of a coarse grained breccia conglomerate (after McLeod, 1955 and Spry, 1957) which contains angular and rounded fragments of quartz and white micaceous quartzIte up to nine Groups Grade of Metamorphism inches in size. The particles of micaceous quartzite Fincham Group Chlorite zone are considered by Mather to have been derived from Franklin Group Garnet zone the underlying Fincham Group and to indicate Mary Group Chlorite zone erosional unconformity. Mather also considered Joyce Group Garnet zone the marked decrease in the stratigraphic thickness of the Fincham Group as it is traced along strike to the south-east to be due at least in part to c. Elliott Range erosion which took place between the late Pre cambrian and the deposition of the Owen Conglom The Tyennan unconformity at the north end of erate (Lower Ordovician) . The apparent conformity Elliott Range was originally described by Carey as expressed by the similar attitudes of the two and Banks (1954, p. 255). The unconformity is well is considered to be due ,to the shallow dip of the exposed in a near vertical cliff section and consists Precambrian in this area at the time of the de of well bedded white quartzites and pebble con position of the Owen Conglomerate. This would glomerates (Owen Conglomerate) which overlie suggest broad folding of the Fincham Group prior Precambrian siliceous schists. to the deposition of the Owen Conglomerate; later folding has produced the present steep attitude of these sediments. d. Sprent River The exposures north and south of Sprent River indicate a broad anticlinal structure with a central b. Mt. Fincham Area (McLeod, 1955, p. 13) portion of metaquartzites and siliceous schists and Similar conditions apply here as in the Andrew margins of quartz pebble conglomerate and sand River area. The actual contact betwen the Owen stones which have been correlated with the Owen Conglomerate and the Fincham Group was only Conglomerate. The latter sediments form the seen in one place. Here breccias and conglomerates prominent cuesta of Sprent Ridge which is striking 100 0 and dipping 50 0 to the south occur immediately to the north of the Sprent River. On within twelve inches of a purple quartzite of the the western margin the strike of the Precambrian Fincham Group whose strike varies from 090 to and Owen Conglomerate is comparable but with 1200 with a dip of 70 to 80 0 to the south. At a the suggestion of a steeper dip in the former sedi number of other places rocks on either side of the ments. On the eastern margin the Owen Con contact were farther apart and the evidence for glomerate trends nearly north-south with the Pre a structural unconformity between the Owen Con cambrian horizons trending east-west. The overall glomerate and Precambrian is less conclusive owing structure can be best explained by an anticline in to the varialble dips which occur in the latter. existence prior to the deposition of the Conglom erate with refolding after their depOSition about an A correlate of the Jukes Breccia was seen, axis some one to two miles to the west of the occurring as half a dozen loose blocks which con previous one. tained ·a predominance of rock particles up to three inchs in size but with some to six inches. The The above descriptions allow the establishment fragments include massive and schistose quartzites, of an unconformity between the Junee Group and micaceous schistose quartzites, and some reddish pre-Dundas Group rocks for a distance of 35 miles, massive quartzite. from the north end of the Engineer Range (Mt. McLeod concludes that usually the strike of the Madge) southwards to Mt. Lewis. Owen Conglomerate and older rocks is similar and that the unconformity is shown by a steeper dip of about 20 degrees in the latter rock. He suggests e. Warnes Lookout (Wells, 1955, p. 5) (p. 14) that part of the Owen Conglomerate was The Owen Conglomerate has an irregular boun deposited around a hill or island of quartzites in dary with the underlying schists. The contact itself the Lower Ordivician topography. is not clearly visible and the possibility of a faulted B. SCOTT 105
contact cannot be entirely discounted, especially be the localities to seek the unconformity. It is the on the western margin of this outlier of Conglom western edge which is described by Ward and Finu erate. However, on the eastern margin Wells states cane and Blake. the existence of a breccia which contains angular fragments up to eight inches in length which he g. Bubbs Hills (16 miles east of Queenstown) possibly correlates with the Jukes Breccia. Photo geological interpretation would place faults along Gould 0860, p. 12) was the first to be aware of the northern, western and southern margins of the the unconformity between the "Lower Palaeozoic outlier but the eastern contact with the underlying rocks " and " metamorphic schists" in this general rocks is irregular in outline. area. Carey and Banks (1954, p. 255) infer an un On this basis a Tyennan unconformity can be conformable relationship between the Junee Group inferred at Warnes Lookout. and pre-Dundas strata at Bubbs Hill. Recent mapping supports these previous observations (and J. Loddon River-Calder Pass those of Ward, 1908, p. 35 and map facing p. 44) of flat lying Gordon Limestone (capped by white Ward (1909, p. 50) described an unconformity in Crotty Quartzite) which probably lies directly on the Loddon River valley. The upper group of sedi contorted and steeply dipping Precambrian schists. ments, Ward's "pebbly conglomerate beds" and Mapping approximately two miles to the north-east "tubicolar sandstone ", are now known to be part of Bubbs Hill estlllblished the presence of white of the Junee Group which rests directly upon the fossiliferous quartzites (these were correlated with quartz mica schists of the area. Ward evidently Crotty Quartzite on lithological grounds) which noted this unconformity in more than one location appear to directly overlie the Precambrian schists for he writes: of the area. The Precambrian and Junee Group "The several members of this sedimentary rocks both trend east-west but the former dip to series (Junee Group as IlIbove--author) rest the north at 60 to 80 degrees whilst the latter have directly upon the quartz-mica schists in every a flatter dip, usually less than 45 degrees to the case which was observed, and there is a marked north. Thus although no actual erosion surface unconformity at the junction with the foliated was exposed a Tyennan Unconformity can be said rocks ". to exist, with some confidence. . Later in this same report Ward (P. 34) describes h. Mt. Arrowsmith (Carey and Banks 1954, p. 257; the same unconformity further to the south at Ward 1908, p. 37, and 1909, p. 32) Calder Pass. He writes: ' " The northern branch of the pass follows the Two exposures of an unconformity between Owen line of junction ,between the tubicolar sandstone type conglomerate and Precambrian siliceous and the mica schists which constitute the schists were described by Ward 0908, 1909) on the eastern foothills of the Frenchman's Cap". summit of Mount Arrowsmith. Finucane and Blake (1933) also recognised this "On the north-western portion of the summit of Mount Arrowsmith, and 1600 feet above the unconformity from the South Loddon River where Franklin River Bridge, there is left an undenuded the basal members of their Silurian rocks could be portion of a sedimentary basin, the full extent seen resting unconformably on the Precambrian of which is not now clear. The strata consist of schis~s. At the base of these younger rocks they bedded shales, sandstones, and fine grained con descnbe the presence of a coarse breccia-con glomerate which dip at an angle of five degrees glomerate which consists of " angular and rounded to the west. The sandstone contains some imper pebbles of quartz and quartzitic schist set in a fectly preserved impressions of brachiopods, highly siliceous ground mass; the schist pebbles which are probably of Silurian age. At this place are identical with the quartzitic schists of the Pre the area covered by the sediments is very small, cambrian rocks and have doubtless been derived and fills a hollow in the hard quartzitic schist, from them ". to the endurance of which it owes its preserva Wells (1955, p. 5) in discussing the geology of tion. The rest of the summit of Mount Arrow the Calder Pass describes "white silicified con smith is wholly of the white foliated quartz glomerate containing pebbles of quartz of the order schist ". of one cm. diameter ", which underlies the tubi colar sandstone. Although he did not examine the Later on the same page Ward describes another base of this Owen type conglomerate he considers unconformity on the east side of Mount Arrow it likely that an unconformity exists between these smith. .sediments (Junee Group) and the Precambrian " A low hill on the northern side of the Linda rocks of the area. Track proved to be composed of medium-grained quartzite. In all respects this quartzite resembles A compilation of the work of Ward, Finucane very closely the reddish quartzite which is assoc and Blake, and Wells and using this as a basis of iated with the West Coast conglomerate. The photogeological interpretation of the area has dip is north-westerly, at an angle of 40 degrees. outlined a basin of 20 square miles of Palaeozoic rocks which rest directly on Precambrian, situated This formation rests upon a floor of quartzite between the Loddon River and Calder Pass. Its schists " north and south extremities appear to be primarily In the report for 1909 (p. 32) Ward describes in faulted relationship with the Precambrian but this latter occurrence as resting unconformably the eastern and western edges of the basin would upon the Precambrian schists. 106 LOWER PALAEOZOIC UNCONFORMITIES IN S.W. TASMANIA i. North End of Denison Range (Carey and Banks, k. Mt. Hopetoun (Carey and Banks, 1954, p. 261; 1954, p. 257; Twelvetrees, 1908, p. 30) Stephenson, 1954, p. 151) Twelvetrees (1908) walked from the Rasselas Mt. Hopetoun is six miles north-east of Federa Valley, with its occurrence of sediments of the tion Peak. The unconformity described by Steph Junee Group, westwards into the north end of enson at Mt. Hopetoun and correlated by Carey the Denison Range, to Lake Curly, and beyond. and Banks as possibly Tyennan is now most suspect. Recent photogeological work and regional consid " About a mile west of this the schist country erations make it highly probable that the siliceous is entered. The general strike of the strata now peblble conglomerate described by Stephenson is alters. Previously it was west of north (in a Precambrian unit and not an Owen-type con the Rasselas Valley-author); now it is east of glomerate of Ordovician age. This unconformity north, and this was a stable character as far between conglomerate and underlying schist would west as we went. There is thus a strong un then be placed within the Precambrian. conformity between the Precambrian and the Cambrian strata". 1. Wedge River Valley (Carey and Banks, 1954. Twelvetrees travelled as far west as the Prince p. 261 and Twelvetrees, 1909, p. 29) of Wales Range. The Cambrian strata are now known to consist of the Owen type conglomerate, On the basis of a regional compilation and photo Gordon Limestone and the younger, Eldon Group, geological interpretation of the general Adamsfield rocks of the Rasselas Valley and general Florentine area the unconformity in the Wedge River Valley, River area. provisionally correlated as Tyennan by Carey and Banks, is suspect. The determination of this point " At the junction of the systems . . . is a . . . must await a more adequate definition of the age breccia of large, angular stones of quartz and and structure of the sediments of the area between quartz schists, which is situated between the the Ragged and Junction Ranges (Denison Plain). upper members of the schist and the basal sand stones of the conglomerate series". This breccia corresponds to the Jukes Breccia. UNCONFORMITY BETWEEN DUNDAS GROUP Approximately five miles to the north of Twelve AND PRE-DUNDAS GROUP ROCKS trees east-west traverse on the south side of the lower Gell River valley, a marked structural dis a. Point Hibbs-Macquarie Harbour cordance is apparent between the Junee Group and underlying Precambrian schists. The structures The relationship in this area is complicated by are quite clear on the aerial photographs. The the major faulting which is strongly suspected to Owen type conglomerate (apparently now thinner be present along the contact of the two and by a than to the south) and overlying Gordon Limestone belt of ultra-1basic rocks which occurs along this swing from a general strike of 345 degrees in the eastern 'boundary from Point Hibbs to Macquarie Rasselas Valley to 285 degrees in the Gell River Harbour. However, between Birch and Point Hibbs Valley. The general dip to the north-east is main the direction of folding in the Dundas Group is tained at both localities. The Gell River here marks N.W.-S.E. whilst immediately to the west of this the northern end of the Denison Range; at this in the Precambrian the regional strike and direction northern termination the Precambrian schists of of folding is N.N.E. On this basis an unconformity the Range maintain their regional strike of 020 to between the two can be inferred. 030 degrees and plunge beneath the 285 degree trend of the overlying Junee Group. b. Adamsfield j. Tim Shea (Carey and Banks, 1954, p. 252; At Adamsfield the occurrence of the serpentinite Twelvetrees, 1908, p. 27 and 1909, p. 27) and overlying shales and conglomerate which con sists entirely of particles derived from the serpen Carey and Banks describe the unconformity tinite has been descr~bed by Carey and Banks (1954, which exists at Tim Shea between Owen type con p. 26). These sediments in turn are overlain by glomerate and underlying Stephens Dolomite. The Owen type conglomerate. The age of these shales crest of Tim Shea is composed of Owen type con has recently been determined by Opik (pers. comm. glomerate and quartzite which strike north-east M. R. Banks, 1959) who suggests that these rocks and dip to the north-west at a shallow angle of could be middle Uper Cambrian, thus placing the about 15 degrees. The underlying Dolomite strikes underlying unconformity as Stichtan. This exposure north-west and dips at a steep angle to the north is approximately one mile east of the post office east (70 to 80 degrees). Between the two a con at Adamsfield, immediately north of the track. The glomerate exists which consists of particles of the base of the Palaeozoic/original top of the ultra underlying Dolomite. basic is also exceptionally well exposed at approxi mately one mile to the north of the former locality, This is the type locality for a Tyennan Uncon on the south side of Hopper Creek. formity. The dating of these sediments has 'had the The map on page 249 of Carey and Banks shows important corollary of placing the intrusion of the that the direction of folding in the Precambrian associated ultrabasic as being older than previously here is nearly N.N.W. whilst that in the overlying thought and as taking place prior to or during Junee Group is N.N.E. to north. the deposition of the Dundas Group. B. SCOTT 107 c. Rocky Boat Harbour-Prion Bay (Blake, 1938 ang trending sequence of serpentinous conglomerates, Banks, 1959) sandstones and claystones further to the west. Banks (959) gave the first description of a Elsewhere on the east side of Prion Bay these latter probable Stichtan Unconformity in this area. The sediments underlie Owen type conglomerate. These tough, grey dolomite with a trend of 010 degrees serpentinous conglomerates, &c., resemble those at and an almost vertical dip is unconformably over Adamsfield further to the north, as already lain by a sequence of polymictic conglomerates described above. These former sediments at Adams with minor siltstone and sandstone beds. Among field have been dated as probably middle Upper other rock types the conglomerate contains particles Cambrian thus making it possible that the same of the underlying dolomite, and serpentinite. This unusual rock assemblage at Rocky Boat Harbour sequence is in turn overlain by Owen type con is also Upper Cambrian. glomerate. These rocks above the dolomite trend Owing to the thickness of the bush in this area north-easterly and dip at angles of less than 45 the critical area which is the coast line immediately degrees. to the west of Prettys Point could not be reached. The dating of a similar unusual rock assemblage A photogeological interpretation of this area indi at the base or below the Junee Group at Adamsfield cates that the angular relationship described above (page 106) as probably middle Upper Cambrian is clear-cut and the possibility of it being due to makes it probable that the assemblage here is also a sharp swing in strike is considered to be remote. of a similar age. If this is correct the unconformity can 'be related to a Stichtan Unconformity. PALAEO GRAPHIC IMPLICATIONS UNCONFORMITY BETWEEN JUNEE AND The implications of the three types of uncon DUNDAS GROUPS formity have already been outlined by Carey and Banks 0954, p. 265). Usually in S.W. Tasmania the contact between It is clear that the areas containing a Jukesian the Owen Conglomerate and underlying Dundas Unconformity received Dundas Group sedimenta Group has been complicated by major faults. Thus tion, followed by Jukesian Movement, erosion and Whilst structural discordances between the two may deposition of sediments of the Junee Group. The be apparent (e.g. at the D'Aguilar range) this could deposition of this Group began with the Jukes as well be due to faulting as to an unconformity, or Breccia and coarse grained Owen conglomerate type a combination of the two. of sedimentation as seen in the West Coast Range and the Sawback and Ragged Ranges at Adams a. Mt. Jukes, Mt. Darwin, Mt. Sorell field. It is most probable that progressively younger As already described on page 1, Hills 0914, p. 43) formations of the Owen type conglomerate over was the first to describe in detail a Jukesian Un lapped the older which would be a corollary of a conformity. His work has been largely confirmed transgressive early Ordovician sea. It is to be by later workers as Bradley 0954, 1956) and noted that the transgressive sea would make the Solomon (957), basal breccia-conglomerate of the Junee Group (Jukes Breccia-Conglomerate) transgressive in b. Adam River time, that is the correlate of the Jukes Breccia at Nye 0929, p. 10) inferred an unconformable Warnes Lookout and similar areas would probably relationship between the Owen type conglomerate be younger than the corresponding rock type at, of the Ragged Range and the underlying sediments say, Mt. Jukes or Mt. Darwin. As the sea trans exposed in the Adam River which were described gressed, the land area between the two main basins by him as Cambrian in age. On lithological and of deposition at Adamsfield and on the West Coast structural grounds these latter sediments can be would finally be completely reduced and either tentatively correlated with the Dundas Group. submerged or aproaching a peneplain. Sedimenta This correlation is supported by the recent dating tion continued with deposition of the Caroline of the sediments underlying the Owen type con Creek Sandstone and the Gordon Limestone. glomerate at Sawback Range at Adamsfield as The structural discordances illustrated by the probably middle Upper Cambrian in age. Stichtan Unconformity described above demon The conglomerate of the Ragged Range has a strates that the pre-Dundas Group rocks were regional trend of 195 degrees and a dip of 45 to folded prior to the deposition of this Group. This the east. The underlying sediments exposed in the direction of folding would appear to have been Adam River below the falls are interbedded red largely north-south although it is difficult to remove and brown mudstone, light green and purple shales the effects of later orogenic movements from the with red, cream and light-green coloured chert pre-Dundas Group rocks in the absence of detailed bands which trend 150 degrees and dip at 60 degrees structural studies. Later folding (post Lower Ordo to the east. On this basis an unconformity could vician) was either approximately parallel to the be inferred between the two types of sediments but existing axes (as at Sprerrt River) or discordant their actual contact at the Adam Falls is con to it, as at the Tim Shea and Gell River localities. sidered to be a faulted one. A major problem is whether sediments of the Dundas Group were ever deposited on areas show c. Prion Bay; Rocky Boat Harbour and Prettys ing a Tyennan Unconformity. Sedimentation in Point the Dundas Group apears to thin rapidly towards Banks (959) inferred an unconformity between these areas but two interpretations are possible. the north-east trending Caroline Creek sandstone Either the Tyennan areas received a cover of on the east side of Prettys Point and a south-east Dundas sedimentation which was stripped off in the 108 LOWER PALAEOZOIC UNCONFORMITIES IN S.W. TASMANIA ensuing Jukesian Movement to completely expose HILLS, C. L., 1914.--The Jukes Darwin Mining Field. TaB. the underlying pre-Dundas rocks, or the Tyennan Del)t. Mines. Geol. Surv. Bulletin, No. 16. MATHER, R. P., 1955.--Geologlcal Report on 10 KUoyard Sheet areas were emergent during this period. In my 3778. 'rhE> Andrew River Area. Unpublished Report, of opinion a choice cannot yet be made between either H.E.C., Tusman'ia. alternative. A thin cover of Dundas sedimentation McLEOD. 1. n., 1955.-'rhe Geology of the Mt. Pinc-,nam could have been deposited on the Tyennan areas Map Squ!1.re 3780. Unpublished Rep(}Tt of II.E.C., 'fnanio.... the thinning of these sediments towards the Ny", P. B., In2,9.--The Osmiridium Deposit" of the Adamsfleld Tyennan areas could just as well be due to an District. 'l'as. Dept. of Mines Geol. Survc Bvlleiin No. erosional effect of the Jukesian Movement as a 39. deposition thinning; there is no conclusive evidence OPIK, A. AO j 1951a.-Note-s OIl the Stratigraphy and Palaeon toJogy of Cambrian, Ordovician and Silurian Roclcs in yet avails,ble on this point, Tasmania. Bur. Min. Res. Ceol. & Geophy. Rec. 8, 1951~,55. 1951b.-Cambrian Fossils from Leven rras. Bur. !viin. Res. G601. & Geophu. REFERENCES BANKS, M. R., 1956. "-The Dundas Group (Middle and Upper , 1959.-1n letter from M. R. Banks. Geology Dept., Cambrian Series) and its Correlates in Taslnunia. Univer.\:;ity of rrasrnania.. to G. F. Hudspeth. Mt. Lyell XXth Int. Gool. CongTes:~. Carnbrian Sy'mposiu1n. l\Hning & Railway Co. Ltd.; Queenstown. Tasmania. "- --. 19517.--~Stratigl'aphy of T'u[.;mauian Lirnestone. SO,LOMON, ]\II., 1957.-Geology of the West Coast Range TaB. Dept. of Mines. Geal ..Surv. Min. Res. No. 10. Mt. Sedgwick to' South Darwin.. Unpublished Report ~------"- ~-, 1959.---·Prelinlinary SUITlmary of the Geology Mt. Lyell Mining & Railway Co. Lim.ited, Queenstown, near Hocks Boat Harbour, Southern Tasma.nia.. U-n,- rrasmania. 1)-ublishet;l Report to Lyell-B.Z. E'xplorat'ion.s, Q'UeenstoVJn,~ SPRY~ A. M., 1957~·----·Preca.mbrian Rocks Tasma.nia. Part II. Ta81'nan~a. Mmrnt Mary Area. Pro-c. Roy. Soc. Vol. 91. jJ. 95. BLAKE, F., 1936. -~Distr.ict between Jane River and Prince of Wales Range. Ta,a. Del)t. oJ lVlines Unpublished Report. STEPHE,NSON, ~J., 19514.-An unconformity in South-"lNest Tas -, 1937.-~Report on Geologieal Reconnah;sance of mania.. Proc. Roy. Soc. 'l.'aS'YIt., Vol. 88, pp~ 151-152. Surveyor and Prince of Wales Range. Tns. Dept. of Mines TWELVET'RE'ES, W. H., 1908.-TaB. DelJt. Lands & Surveys Ann/ha.l Unpublished Repm't. Report, 1907-1908, pp. 28-32. BRADLEY, J'.~ 1954.~Geology of the WeRt Cbast Rang'e of Tas~ .------. r1909.-Ta,g. Dept. Land.'] & Surveys An/Hultl mania. Proc. Roy. Soc. Tas., VoL 88, PD. 193-240. Report. 1908-1909, pp. 25-31. CAREY, S. W. AND BANKS, M. R., 1954.-Lower Pa.laeozoic Un WAUD, L. K., 1H08.-Tas. Dept. Lwnds & Surveys Annual Report, conformities in 'T'asmania. Pap. N Proc. Roy. Soc. Tasm., 19,07-1908. pp. 33-3H. 1954. p. 245. FINUCANE. K. J. AND TILAKFJ, F., ID33.-Country between West ------, 1909.-Tas. Dept. Lamds & Surveys An'rn.tul RfJ1)o'fi,. Coast Road and .Jane River. 'Pas. DeJJt. O'f Mines Un 1908-1909, PP. 31-35. publ-ished Report. WELLS. B., 1955.-Report on the Geology of Map Square GOULD, C., 1860.-Re-port on the Exploration of the- Western .RH7R and parts of adjoining- squares 38'78 and 4078. Un Country. Leg. Council Paper Noo 6, Tasmania. 'j)ubUshed Repo'rt of H.E.C., Tasman'la. B. SCOTT 109
SOUTH WEST TASMANIA
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Scale: 16 miles to 1 inch. FIGURE I.-Location Plan of S.W. Tasmania. 110 LOWER PALAEOZOIC UNCONF ORMITIES IN S.W. TASMANIA
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;}~ S.--,,' --t '( ,- \ '\ " ------1 ~ 'j ,'~.""');:------I 5 , ,,------1 \, SOUTH WEST LEGEND I:I 1'\------1 TASMANIA I I '}.------I CaInOZOIC EE6 , Mesol.olC E:l Other PalaeOZOIc [LJJ] I ~,,~-----__I Dundos Group [;::::;] 1 1 ,\ I/~' .:<:.:t------t Pr'"~combrion c:::J Gronite ~ . ",11"----1 Fault I , l/;-----f Antieline -+ Syncline -+- , " ~ Boundarl::l Scale: 16 miles to 1 inch. FIGURE 2.-General Geoioll'Y of S. W. Tasmania.