Phillip Island Excursion Site 18: Cowes

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Cowes
Cowes

Cowes, the main town of Phillip Island, faces north into Western Port, and looks toward French Island and the Mornington Peninsula. There are many shops, including restaurants, cafés, art, craft, and souvenir shops and a historical museum at the Heritage Centre in Thompson Ave (Phillip Island Rd). Public toilets are on The Esplanade, at the end of Thompson Ave, and at the end of Findlay Street.

There are good outcrops of basalt alongside the jetty where you can check for the texture of the rocks, the thickness of the lava flows, the presence of holes (vesicles) in the lava. Note the red colour of the rock alongside the jetty indicating that the basalt has been altered from the usual black colour by the oxidation of the iron in the lava.

Seaguls on basalt wall Cowes
Seaguls on basalt wall Cowes
Some of the stone walls in the area (e.g. one leading to the jetty and another alongside some shops on The Esplanade) are made of basalt rocks. Some of the rocks have been broken so you can see the interior colour and texture of the basalt. The black colour of the basalt is due to it being rich in iron and magnesium. What minerals can you see? Other rocks in other walls are whole and some are filled with holes, or vesicles, which formed as a result of the gases in the lava escaping and bubbling to the top of the lava flows.

Along the beach about 200 metres to the west is another outcrop of basalt (Mussell Rocks) but quite black in appearance.

There are some nice walks that follow the beach starting at the end of Thompson Ave (Phillip Island Road)—one to the west and another to the east.

Significance

These deposits illustrate the geographical extent of the volcanic eruptions. The holes (vesicles) in the basalt point to the release of gases during the eruptions. The basalt rock suggests the molten rock (magma) was generated deep inside the earth below the granitic continental crust.

Guide available as a booklet
This entry is taken from the geological excursion guide for Phillip Island. The complete guide is available as a booklet on creation.com Aussie store.

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