Towns Ville Queensland
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COMMONWEALTH OF AUSTRALIA 1: 250,000 GEOLOGICAL SERIES-EXPLANATORY NOTES TOWNS VILLE QUEENSLAND SHEET SE/55-14 INTERNATIONAL INDEX Compiled by D. H. Wyatt (Geological Survey of Queensland) Issued under the authority of the Hon. David Fairbairn, Minister for National Development · BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS CANBERRA 1968 COMMONWEALTH OF AUSTRALIA DEPARTMENT OF NATIONAL DEVELOPMENT MINISTEa: THE HON. DAVID FAmBAII\N, D.F.C., M.P. SECR.ETAlW: R. W. BOSWELL, 0.B.B. BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS DmE'cro1t: J.M. RAYNEll, 0.B.E. THESE NOTI!S WEllB PllEPAll£D IN TIil! OEOLOOICAL BllANCH ASSISTANT DtllECTOll: N. H. FISHEil Printed in Australia by the Commonwealth Government Printer, Cant:erra Compiled by D. H. Wyatt Explanatory Notes on the Townsville Geological Sheet The Townsville 1 :250,000 Sheet is bounded by longitudes 145 ° 30' and 147° O' E. and latitudes 19° and 20° S. It covers the coastal areas north and south of Townsville, the second largest city in Queensland, and the hinterland west to beyond the Burdekin River. Access within the area is good, but routes are frequently circuitous owing to natural barriers such as the Coane Range in the north, the Paluma, Hervey, and Leichhardt Ranges in the east, and the Burdekin River in the west and south. The main roads are the Bruce Highway (Hwy 1) along the coast, the Flinders Highway (Hwy 78) south from Townsville to Reid River thence southwest to Charters Towers, and the Ewan-Paluma road, which joins Highway 1 just north of the Sheet area. A system of subsidiary shire roads connects cattle stations with these roads, and station tracks connect neighbouring stations, outstations, and watering sites. Rail services connect Townsville with Brisbane and Cairns by the North Coast Railway, and with Mount Isa by the Great Northern Railway. Air services extend north and south from Townsville to most coas·tal towns, and west of Townsville services extend to most inland towns as well as Mount Isa and Darwin. A few station properties are serviced regularly by light aircraft, and many properties have landing strips suitable for light aircraft. Climate The climate is warm and dry in winter, and hot and wet in the summer. The wet season, which is not always reliable, lasts from November to March. Rare frosts occur on the inland uplands. West of the Paluma and Hervey Ranges, rainfa11 is between 20 and 30 inches per annum; east of that line it ranges between 30 and 50 inches, except for a small area in the extreme north, where it is over 50 inches. Vegetation Most of the area is covered by open forest, woodland, or savannah; the higher ranges near the coast are covered by tropical rain forest. Previous and Contemporary Investigations The first geological observations in the area were made by Leichhardt (1847) who recorded limestone at Terrible Creek (probably the present Arthur 1 10713/ 68-2 Creek) near Burdekin Downs. Jack made four reconnaissance traverses through the area between 1879 and 1887. On the first of these (1879a), he described the Star Beds, the Dalrymple-Dotswood Beds, the limestone at Burdekin Downs, the pre-Devonian granite and metamorphics, and the strata now assigned to the Collopy Formation. During his second traverse later in 1879 ( 1879b), he described volcanics between Keelbottom Creek and Fanning River, which are now assigned to the Carboniferous, and the limestones at Fanning River and Reid River. As the result of his third traverse in i 886, when he described the silver mines at Argentine, he equated his Star and Dotswood Beds (1886f). In 1887 he briefly described the geology of the Continong-Dalrymple-Dotswood area ( 1887b). As a result of these traverses the broad outline of the regional geology was established. L~ter work . was directed mainly towards individual mineral deposits. How ever, Maitland (1891) made brief mention of the limestone near Ewan, and described strata of the present Kangaroo Hills Formation, which be assigned to the Devonian. Jack in 1892 mentioned the limestone at Ewan more fully in his description of the associated silver-lead deposits. In 1892, Maitland described the geology of the Townsville/Stuart/Magnetic Island region (1892a, b).In 1893 he made brief mention of the geology between Charters Towers and Hillgrove while reporting on silver deposits in the Stockyard Creek area. Jack (in Jack & Etheridge, 1892) summarized the geology of the area. Since 1900, numerous reports on mineral deposits, mainly in the Kangaroo Hills Mineral Field, have been made by officers of the Geological Survey of Queensland; they are listed in the Bibliography. The limestones in the Reid Gap area have been described on numerous occa sions, especially since 1955, when Carruthers made a reconnaissance geologi cal survey of the area l}955a). Morton (1928) had previously delineated many of the limestones. Most of the later reports deal specifically with reserves of individual limestone occurrences. A survey of the land characteristics of the Townsville-Bowen Region was carried out by CSIRO in 1950. The report on the survey (Christian et al., I 953) contains a reconnaissance geological map (by D. M. Traves) which takes in the Townsville Sheet area about as far west as longitude 146° 40' E. The systematic geological mapping of the Sheet area was begun in 1960 by the Geological Survey of Queensland, and continued during 1961 and 1962. The mapping was completed by a joint Geological Survey of Queensland and Commonwealth Bureau of Mineral Resources field party in 1963. A report on the results of this mapping is in preparation (Wyatt et al., in prep.). 1 : 250,000 geological maps and explanatory notes for the adjoining Sheet areas are either available or in preparation, as follows: Ingham ( de Keyser ~t al., 1965), Clarke River (White, 1962), Charters Towers (Clarke, in prep.), Ayr (Gregory, in prep.) and Hughenden (Vine & Paine, in prep.). PHYSIOGRAPHY The Townsville Sheet area is divisible into three main physiographic units: Coastal Lowlands, Coastal Hills and Mountains, and Inland Uplands (Fig. 1). 2 The Coastal Lowlands extend east from the foot of the Paluma, Hervey, and Leicbbardt Ranges. They consist essentially of_outwash plains formed by an old distributary river system. Close to mountainous country_ the plains merge into alluvial fans. North of the Ross River most streams flow directly to the sea in deeply incised channels with relatively straight· courses. South from the Ross River valley, between Frederick Peak and Mount Stuart, the low lands form a corridor between the Hervey Range and the Coastal Hill Country, and link the plains of the Haughton River in the south with those of the Bohle and Black Rivers in the north. This corridor is drained by tributaries of the Ross River, Landsdowne and Five Head Creeks, which flow north from a low, almost imperceptible divide at Woodstock. This divide separate.s them from the tributaries of Major Creek, which flows southeast to the Haughton River. The divide was probably an eminence in the original surface of deposition, and is not due to subsequent erosion. ~::=-J Undulating country 0 10 20 Miles INLAND UPLANDS f:f~~J')ij Dissected low ploteoux G .j Coastal lowlands k;~t j Ronges l''\c·/c:J Coastal hills and mountains Fig. 1. Pbyslograpblc Units.l East of the Coastal Hill Country, the lowlands consist of outwash plains and fans merging with tidal flats in which streams have meandering courses, pro bably due to the iryfluence of tidal currents and aggradation on the present coast. A detailed study of the coastal lowlands about Townsville was made by Hedley ( 1925). The Coastal Hills and Mountains consist of residuals surrounded by the Coastal Lowlands. The highest point is Mount Elliot ( 4025 feet), the highest peak in the Townsville Sheet area, but generally the elevation is less. The Inland Uplands occupy the greater part of the Sheet area. They consist primarily of a dissected peneplain which, over most of the area, has a regional westerly slope. Elevations in this region vary considerably, and are closely related to rock-type. Relief also varies considerably, and is related to rock-type and the degree of fracturing or faulting. The uplands are divisible into three subunits: · Undulating country occupies the central and southern parts of the uplands. It has generally low relief, although in places it may be rugged. It corresponds generally to the outcrop areas of the Ravenswood Granodiorite, and the Silurian, Devonian, and Carboniferous sequences. Dissected low plateaux of Cainozoic rocks occupy the southwestern part of the region. The plateaux are not greatly elevated above the undu.lating country; in fact they may be termed plateaux only with regard to the immediately adja cent country, for a few miles farther east much of the undulating country is higher than the plateaux. In the Cainozoic sedimentary areas, the low plateaux, which are between 20 and 60 feet above the surrounding country, are much dissected by stream erosion. In the Cainozoic basalt areas the plateau margins are only 10 to 20 feet above the surrounding country, but the plateau formed by the N ulla Basalt (Nulla Plateau of White, 1962) is dome-shaped so that its central part is some 300 feet higher than its margins. The basalt plateaux are less dissected than the sedimentary plateaux, but many of the streams are deeply incised. The Cainozoic basalt flows had a marked influence on drainage in the south west For example, some of the flows were confined by the course of the Burdekin River, whose old channel can be traced by their remnants. With the filling in of the stream course by basalt, the river was forced to find a new course farther to the east.