OUR VOLCANOES

The Warrumbungle Range is a spur of the Great Dividing Range and forms a large semi-circle to the west. This area contains two ancient extinct volcanoes. The oldest one is known as the Garrawilla Volcanics and is located about 40 km to the east of the town of Coonabarabran. It consists of a basement of the Permian Black Jack Formation (coal), overlain by the sedimentary Triassic Digby and Napperby Beds. After these beds were laid down, the area was subjected to a period of intense volcanic activity. Eruptions of flows and pyroclastics, from numerous centres, produced a thick volcanic pile, the Garrawilla Volcanics.

This Volcano was active from about 200 million years ago until it stopped about 45 million years ago. Sedimentary rocks of the Purlewaugh and Pilliga Beds overlay these flows in the south and west, suggesting that much of the Garrawilla Volcano remained as an island or peninsula in the Jurassic Sea, about 120 million years ago.

An area in this volcanic complex, about 40 km long and 7 km wide, produced the rare and colourful Zeolite Crystals on display in the Crystal Kingdom.

The Warrumbungle Mountains, to the west of Coonabarabran, is a much younger volcano. This one started about 17 million years ago and finished about 13 million years ago. At that time, the landscape was very much like it is today.

The early eruptions consisted mainly of trachyte, a very viscous type of lava. These formed the spectacular spires and domes you see today.

The later eruptions were of the more fluid basalt type, which flowed over the top of these and created a large Shield Volcano. Most of this basalt is eroded away and the older trachyte vents are now dominating the landscape.

The Warrumbungle volcano is Australia's most spectacular shield volcano and is the most westerly volcano in eastern Australia. It encompasses a wide variety of microclimates where species from completely different environments can be found near each other. For example, on some high ridges there are grass trees growing in the same area as snow gums. There are many different timbers, wildflowers and habitats for birds and wildlife. Being a nature lover’s paradise with over 360 species of birds being counted in our local area. Many species of wildlife are also found here including possums, sugar gliders, wombats, kangaroos, wallaroos, koalas, and wallabies.

Unfortunately for us the Warrumbungles have not worn down enough yet to allow us to discover its interesting minerals. Underneath this lies the much older Garrawilla volcano. This volcanic system stretches from Dubbo, to Narrabri, Gunnedah and at least as far west as Coonamble. At approximately 170 million years of age, it has been worn down to its early history and that is where the rare zeolite crystals have been discovered and the whole area is rich in fossils.