7 A OJ? TASMAN PENINSULA M.R. Banks, E.A. Calholln, RJ. Ford and E. Williams University of Tasmania (MRB and the laie R.J. Ford). b!ewcastle fo rmerly University of Tasmama (EAC) and (ie,a/Ogle,Cl; Survey of Tasmania (E'W) (wjth two text-figures lUld one plate) On Tasman Peninsula, southeastern Tasmania, almost hOrizontal Permian marine and Triassic non-marine lOcks were inllUded by Jurassic dolerite, faulted and overiain by basalt Marine processes operating on the Jurassic and older rocks have prcl(iU!ced with many erosional features widely noted for their grandeur a self-renewing economic asset. Key Words: Tasman Peninsula, Tasmania, Permian, dolerite, erosional coastline, submarine topography. From SMITH, S.J. (Ed.), 1989: IS lllSTORY ENOUGH ? PA ST, PRESENT AND FUTURE USE OF THE RESOURCES OF TA SMAN PENINSULA Royal Society of Tasmania, Hobart: 7-23. INTRODUCTION Coal was discovered ncar Plunkett Point by surveyors Woodward and Hughes in 1833 (GO 33/ Tasman Peninsula is known for its spectacular coastal 16/264·5; TSA) and the seam visited by Captain scenery - cliffs and the great dolerite columns O'Hara Booth on May 23, 1833 (Heard 1981, p.158). which form cliffs in places, These columns were Dr John Lhotsky reported to Sir John Franklin on the first geological features noted on the peninsula. this coal and the coal mining methods in 1837 (CSO Matthew Flinders, who saw the columns in 1798, 5/72/1584; TSA). His thorough report was supported reported (1801, pp.2--3) that the columns at Cape by a coloured map (CSO 5/11/147; TSA) showing Pillar, Tasman Island and Cape "Basaltcs" (Raoul) some outcrops of different rock This map, were "not strictlybasaltes", that they were although not the Australian not the same in form as those Causeway Dictionary of (Vol. 2, p.1l4), was the in COUlltyAntri m, Ireland, and in Auvcrgne, France, earliest attempt at a geological map of any of the subject of great interest in Europe at LiIe time, as Tasmania, The coal was mined from 1834 to It evidence of volcanic activity. Peron (1807, p.261) did no! have a good reputation because of its high recorded that scientists with Nicholas Daudin's ash content (e.g. de la Heche 1851), e)(pedition of 1802 had noted basaitic prisms alld The Tessellated Pavement was known as early needles at Cape Raoul, Cape Pillar, Tasman Island as 1836 when O'Hara Booth examined it (Heard and The Lanterns, and the expedition artists depicted 1981, In 1841 it was visited, probably during the columlls,some of them shown as leaning (Lesueur the by Robert M'Comiick, surgeon on HMS and Petit in Peron 1807, Pl. JH, fig.2), Peron (loc. Erebus then in Hobart between visits to Antarctica. A cit.) wrote of Cape Hauy, named hy the French party including David Bums, made a visit e)(plorers after a famous contemporary French in January 1842 and Bums noted the Pavement later crystallographer, that it as an organ reposing in that year (1842, p.2115). Other visitors, probably in on the surface of the MRS). He further 1842, were P.E. von Strzelecki (1845, p.97) and J.B. wrote (p.248), "Thus even in that extremity of the Jukes (1847). The regularity of [he attracted Eastem World, the earth had its revolutions and its attention and was explamed by (1847, catastrophes; there as everywhere else, it has been pAOO) as due to electromagnetic forces acting on the ravaged by volcanoes raised under the sea" (trans. particles of the sedimentary rock as it consolidated. MRB). Johnston (1888) included lithographs of the 8 MR. Banks, EA. Colhoun, R.I. Ford and E. Williams Tessellated Pavement (opp. p.121), Tasmans Arch compilation by Cromer in 1976 of a geological map (opp. p.124) and The Blowhole (opp. pp.122 and 126) (Cromer et al. 1979). This map forms, with some in his book A Systematic Account of the Geology of ground and aerial surveys by the authors, the basis of Ta smania. Subsequently the Pavement has been the accompanying reconnaissance map (fig.!). figured in overseas publications such as Holmes' After some observations and collecting by Principles of Physical Geology (1944, pI. 14A) and visitors in the 1830s and 1840s little work was done Bloom's Geomorphology(19 78, p.447) and mentioned on the geology and geomorphology of the peninsula and figured by Carey (1957, p.229, fig.l)in Dolerite until the 1950s or even the 1970s. Geological interest - A Symposium and by Branagan (1983) who in the area has been greatest when Port Arthur was described it as "a classic". A similar pavement just a penal settlement and again when conservation and west of Clydes Island wasfigured by David & Browne restoration were set in train. This paper is offered as (1950, vol. n," pI. 76A) in their Geology of the a compilation and �ummary with some new Commonwealth of Australia. Twelvetrees (1902, p.25) observations, but only at a reconnaissance level. and Hills et al. (1922) attributed the jointing to In the following text where geographic co­ contraction during cooling after heating by a subjacent ordinates are quoted they refer to the EN 100 000 body of intrusive dolerite. metre square in grid-zone 55G. The area falls within Fossils fromthe Permianrocks of the peninsula the Storm Bay (8411) and Prosser (8412) 1:100000 attracted early attention (O'Hara Booth in 1836 (in sheets, Department of Lands, Parks and Wildlife. Heard 1981, p.204) and Lempriere 1839 ms. (in Lempriere 1839, p.71)). G.B. Sowerby described two brachiopods from Eaglehawk Neck given to Charles GEOLOGY Darwin by Surveyor-General George Frankland (Darwin 1844, p.177). Lhotsky collected fossil Pre-Permian Rocks brachiopods and bivalves from Curiosity Beach and a bryozoan fromEaglehawk Neck, now in the British The oldest rocks known in the area are quartzites and Museum of Natural History (BMNH). Strzelecki metapelites reported at 362.4 m below sea level in a collected from Point Puer and Eaglehawk Neck and hole drilled just north of Lufra Hotel (760382), and a bivalve from the Point was described by J. Morris correlated with the Siluro-Devonian Mathinna Beds (Strzelecki 1845). M'Cormick's report (1847) includes (Gulline & Clarke 1984). The core from the drill a note by Dr Jeanneret, surgeon at Port Arthur, of hole shows these rocks to be intruded by granitic fossils at Point Puer and the BMNH has an extensive rocks. Granitic rocks crop out beneath the sedimentary collection of Permian fossils from the area made by rocks of the Parmeener Supergroup near Cape Surville Dr Jeanneret and a few in the M'Cormick Collection. further north, and, as isolated occurrences, on J.B. Jukes (1847, p.385) listed bryozoans, Cheverton Rock and the Hippolyte Rocks. The brachiopods, gastropods and bivalves from Eaglehawk granitic rocks are thought to be Devonian by analogy Neck, The Blowhole and Point Puer, many of which with those further north at Maria Island. are now in the BMNH. Frederick M'Coy described (1847) a brachiopod from Eaglehawk Neck and two bivalves from Port Arthur sent to him by the Rev. Parmeener Supergroup - WB. Clarke. Johnston (1888, pl.Xl) figured a bivalve Permian and Triassic "Sanguinolites undatus" from Eaglehawk Neck. No systematic large-scale geological mapping Although a complete section through the lower part of the whole peninsula has been published. Hills et of this supergroup occurs in cliff sections along the al. (1922) included a geological map of the northern east coast of Forestier Peninsula (Gulline 1984) and part of the peninsula, a map shown to be wrong in in the drill hole at Eaglehawk Neck, only the upper part of the Upper Marine Sequence and the Upper places by Brill & Hale (1954). Gill (1955) provided a map of a small part of the peninsula near Safety Freshwater Sequence crop out on Tasman Peninsula. Cove. The northwestern part of the peninsula is included in a recent systematic regional map at Upper Marine Sequence - Permian 1 :50 000 (Gulline 1982, 1984). Conservation and restoration activities at Port Malbina Formation Arthur have led to studies of the geology of the peninsula, especially in areas close to Port Arthur, by This formation, which consists predominantly of officers of the Geological Survey of Tasmania siltstone with some sandstone beds, crops out along (Cromer 1976a, b, Cromer et ai. 1979) and the east coast from Clydes Island to Waterfall Bay Geology and geomorphology 9 TERTIARY OR QUATERNARY Geological boundaries (approx. only) [»»1 Sediments Dips and strikes (N.B. Dips around W, S, E TERTIARY coasts apparent only) _ Basalt JURASSIC + Anticlines [,�,,:-\'�I Dolerite Photolinears TRIASSIC e t Volcanic centres f:::::::::::::j rC _��:I� ���;�r�koSnaceous shale) • PERMIAN -F Faults Mudstone and sandstone l1li Gravel/sand pit DEVONIAN '}t- E:::::3 Granite r ASMAN SEA Cheverton Rock. Hippolyte Rocks Ii!l Hour STORM BAY FIG. I -Reconnaissance geological map o/Tasman Peninsula - mainly after Cromer et al.I979 but with amendments and additions. 10 M.R. Banks, EA. Colhoun, R.J. Ford and E. Williams and possibly beyond. The Tessellated Pavement, Fossil Fern Tree Mudstone Island, The Blowhole, Tasmans Arch and the Devils Kitchen are either composed of or are cut in this The basal unit of this formation, the Risdon formation. Jukes (1847) and Johnston (1888, Sandstone, may be represented by a thin sandstone pp.125-126) described this unit and Voisey (1938, exposed in cliffs of mudstone in Munro Bight and by p.317) assigned it correctly to the Malbina Formation a fossiliferous sandstone from Curiosity Beach (then "Woodbridge Glacial Formation"). (specimen in BMNH).