Tower Hill (volcano)

Aboriginal Australian kitchen middens at Tower Hill show 5000-year-old Tasmanian devil bones.[2] Greenstone axe heads and other artefacts excavated from the tuff indicated that Aboriginal people were resident in the area when the volcano erupted. A basalt tool dubbed the "Bushfield Axe", found buried under volcanic ash near Tower Hill in 1947, was particularly significant. The evidence also aligns with local people's oral histories of volcanic eruptions, indicating the longevity of and truth contained in such histories.[3] The Koroitgundidj people long inhabited this region of Australia and their descendants retain special links with the area.[4]

The most recent eruption was previously dated in 1990 as c.25,000 BP.[5] However, in February 2020, new evidence came to light by using a more sophisticated method of dating than previously, a form of radiometric dating known as argon-argon dating, showing that both Budj Bim and Tower Hill volcanoes erupted at least 34,000 years ago.[3] Specifically, Tower Hill was dated at within 3,800 years either side of 36,800 years BP. Significantly, this is a "minimum age constraint for human presence in Victoria", and also could be interpreted as evidence for the Gunditjmara oral histories which tell of volcanic eruptions being some of the oldest oral traditions in existence.[6] The study was carried out by the University of Melbourne's School of Earth Sciences' David Phillips and three other researchers.[3]

The first confirmed sighting of Tower Hill by Europeans was by French explorers sailing with Captain Baudin aboard Géographe in 1802. Matthew Flinders sailed east along the southern coast of Australia and on 20 April 1802 in the ship's log referred to "Peaked Hill Position uncertain", which may refer to Tower Hill.[7]

The Hill was painted by the artist Eugene von Guerard in 1855, who was the foremost landscape artist in the colonies at the time. The painting Tower Hill, 1855[8] is now in the Warnambool art gallery.[9] The painting was used as a source of information of local native vegetation when an extensive revegetation project was undertaken in the Tower Hill Wildlife Reserve from 1961.[10]

Located about 275 kilometres (171 mi) west of Melbourne and 15 kilometres (9.3 mi) north-west of Warrnambool, Tower Hill's formation is known as a "nested maar", the largest of its type in Victoria. It was created by molten lava pushing its way up through the Earth's crust, before hitting a layer of water-bearing rock, which led to huge explosions. A shallow crater was left, later becoming a lake after it filled with rainwater. Subsequent to this, later eruptions occurred in the centre of this crater-lake, pushing up islands and cone-shaped hills,[12] known as scoria cones.[13]

It is "one of the largest eruption points of the Pleistocene Newer Volcanics Province of Victoria". The main crater is 3.2 kilometres (2.0 mi) by 2.4 kilometres (1.5 mi). Within the steep-walled tuff ring is a crater with a depth of over 90 metres (300 ft). Because of the complex nature of its formation and structure, and as one of the largest maars in the world, it is of great geological significance both nationally as internationally.[13][12]

Tower Hill volcano is roughly 4 kilometres (2.5 mi) and 80 metres (260 ft) high, and as a giant maar (volcanic explosion crater), it is of international and national geological significance. It has a gradient of between 10% to 80% at the higher points.

Now part of the state park system as the Tower Hill Wildlife Reserve, the area had been used since European settlement for farming and stone quarrying. The area has been reforested with native flora, and repopulated with native fauna since 1961

The town of Koroit is on the north rim of Tower Hill, within easy reach of both Warrnambool and Port Fairy.

Panoramic photograph from the Eugene von Guerard lookout at Tower Hill, looking south.
This lookout is located at approximate location from which he painted his Tower Hill, 1855 painting.

Eugene von Guerard's Tower Hill, 1855.

Large panorama of crater, from the south, looking north.
Visible are the scoria cones forming the 'islands' in the middle of the crater, and the lake and far rims of the larger crater.
Note the layering in the far right-hand side of the image.

• List of volcanoes in Australia (active and dormant)

• Parks Victoria: Tower Hills Wildlife Reserve
• Worn Gundidj: Tower Hill