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australia:vic:vicvolcanoes

Victoria's volcanoes

introduction

  • Victoria has one of the largest “young” volcano fields in the world, covering much of south-western Victoria, from the Hume Freeway region of northern Melbourne to Mt Gambier in South Australia in which there are 437 known volcanoes although all appear to be “dormant” rather than extinct.
  • the vulcanic lava flows covered the western plains with basalt rock as well as areas of red scoria rock
  • the volcanic activity over the past 6 million years created this basalt plain with an average depth of the lava of about 60 metres
  • the youngest in Victoria is some 8,000 years since it erupted whilst the youngest in the field is at Mt Gambier which erupted 5,000 yrs ago, and given there appears to have been an eruption every 2,000 yrs on average, experts suggest we are over-due for another eruption, although it is likely to be small and only affect those within a 10-20km radius
  • the Australian tectonic plate continues to move north at five centimetres a year, the plate is hitting up against PNG, lifting the southern margin upwards. This allows magma to move upwards towards the surface and increase risk of vulcanic activity
  • in addition, there are much older vulcanism periods in Victoria's geologic history:
    • 560mya in the Cambrian period, Victoria was covered by ocean but giant volcanoes dotted this ocean floor and formed the oldest known rocks in Victoria such as Cambrian greenstone which can be found in eastern, central and western Victoria
    • in the Ordovician Period (509-446mya), still submerged under the ocean, volcanic activity was restricted to Victoria's far north-east, where a string of volcanic islands extended northwards through what is today south-eastern NSW
    • in the Silurian and Devonian periods (446-359mya), the oceans were retreating and half of Victoria was above sea level, and this period produced Victoria's most explosive volcanoes, the oldest example is Mount Burrowa, in Victoria's north-east. The repeated eruptions were so numerous that in some parts of central Victoria, the volcanic layers are 1km thick. The remains of this peak vulcanic era now form Mount Macedon, the Dandenong Ranges, the mountainous region between Healesville, Warburton and Eildon (including Mount Donna Buang and the Cerberean Ranges) and near Violet Town, in the northern part of the Strathbogie Ranges.1)
    • in the Triassic and Jurassic periods (251-145mya), Victoria was above sea level but covered by glaciers in an ice age (eg. Werribee Gorge). Eruptions were mostly in western and north-east areas.
    • in the Cretaceous period (145-65mya), Australia started to tear away from Antarctica causing depression between Victoria and Tasmania where lakes and swamps formed
    • in the Cenozoic Era (65mya to now), the formation of the Tasman Sea allowed magma from the mantle to reach the surface starting a new period of vulcanism as outlined above.

near Melbourne

  • Organ Pipes National Park
    • a very small park on the Calder Freeway with some nice lava formations including the hexagonal vertical basalt columns of the Organ Pipes, and the Rosetta stone, both adjacent to the Maribyrnong River which provides a nice little woodland walk
    • this extensive lava flow formed approx. 2.5-2.8 million years ago
    • the car park sits on top of a scoria cone
    • restricted hours but free entry although a rather steep 10-20 minute walk back to the car park
  • Mt Kororoit a heavily eroded composite lava and scoria cone on private land
  • Mt Cottrell a major source of lava for the Werribee Plains basalts

further north-west of Melbourne

  • Hanging Rock and Camel's Hump
    • an amazing mamelon formed some 6.25mya - one of Victoria's must visit locations but you should watch the eerie 1970's movie “Picnic at Hanging Rock” first!
    • the rock type here is unique solvsbergite, a type of trachyte, and only shared with nearby Camel's Hump on Mt Macedon, and another nearby hill on private land, and a site in Norway
    • Camel's Hump is high on Mt Macedon but always accessible although can be cold
    • Hanging Rock is restricted hours and pay per car to access but does have a kiosk open daily except Mondays
    • NOTE that these were formed from a much earlier time!
  • Trentham Falls
    • nice waterfall over a basalt cliff
  • Mt Franklin near Daylesford
    • nice free camping ground within the crater of this typical conical volcano although no signficant lava formations
    • and of course it is nearby the tourist region of Daylesford, Hepburn Springs and Maldon/Castlemaine historic gold mining towns
    • head west to Clunes for more awesome volcanic countryside (see below)

www.ayton.id.au_gary_photos_bylens_olympusem5_olympusmzd12mm_ga032136-1.jpg

Trentham Falls

Ballarat region

  • Mt Blackwood in Lerderderg Gorge State Park
  • Mt Warrenheip
  • Mt Bunninyong
    • one of the highest scoria cones in Victoria
    • lavas include olivine-rich xenoliths and megacrysts of clinopyroxene
  • Clunes region
    • awesome area of rolling hillsides created by a multitude of volcanoes
    • Mt Kooroocheang
      • a large composite volcano of scoria and lava with over 200 m of local relief
      • blocks of Ordovician country rock occur in the ejecta.
      • perfect augite crystals up to 1 cm in length have been collected from the volcanic ash of this volcano.
    • Mt Moorookle heavily eroded prominent scoria cone
  • Lexton region
    • most are now topped with wind turbines
    • Mt Mitchell
  • Skipton region

www.ayton.id.au_gary_photos_bylens_panasonicgh1_lumix14_140hd_p1040475.jpg

Clunes gold fields region with a mullock heap from the gold rush days on the left

Hamilton region

  • Mt Eccles National Park
    • this is a really nice spot to explore for the day
    • large lake filled crater
    • outside the rim is a lava canal valley, lava natural bridge, is well worth the 2-3hr walk
  • Penshurst area
    • Penshurst Volcanoes Discovery Centre
    • Mt Rouse a 300,000 yr old volcano with 3 distinct magma types and at least 8 vents, provides lovely sweeping views across the basalt plains to Mt Napier
    • Mt Napier
    • Wallacedale Tumuli 50 basalt mounds rise 11m above the lava flow
    • Byaduk Caves created by volcanic activity

www.ayton.id.au_gary_photos_bylens_olympusem5_olympusmzd75mm_ga158537-1.jpg

Walking through the Lava Canal valley at Mt Eccles

south-western Victoria

  • Tower Hill
    • a really nice example and a must see if passing the Warrnambool / Port Fairy district
    • resulted from eruptions 35,000 years ago
  • Mt Noorat near Terang is a scoria cone with an almost perfect crater 600m wide and 150m deep
  • Camperdown
    • lovely views across volcanic maars
    • various crater lakes
  • Lake Corangamite and Red Rock Volcanic Complex
    • this is the youngest eruption point in Victoria at only 8,000 yrs old, erupted from 40 vents
    • 20 bowl shaped maars
    • Red Rock complex is at Alvie and the interesting parts are on the highest point on the north side with some awesome spatter ramparts, good views to Lake Corangamite
  • Mt Elephant
    • near Derrinallum is a large breached scoria cone with a lava dome and surrounding lava flows
  • The Anakies
    • “This is a complex of three scoria cones and a possible maar. From a distance it appears as a group of prominent hills between the You Yangs and the Brisbane Ranges. Mount Rd runs between the most northwest cone and the maar and is a good way to observe many of the features. Alternatively, you can visit Del Rios vineyard on the southern slopes of the main cone and after a drink at the cafe ask about access. The Lovely Banks monocline runs south from here to Geelong as a linear bank. It is not known if this feature is related to the volcanoes.”2)

www.ayton.id.au_gary_photos_bylens_olympusem5_olympusmzd75mm_ga178849-1.jpg

Volcanic maars from Camperdown

australia/vic/vicvolcanoes.txt · Last modified: 2018/02/11 16:48 by gary1