Geology
The Three Brother Mountains lie on the eastern rim of the Lorne Basin. The Lorne Basin is a sedimentary sequence, consisting of conglomerates, sandstones, mudstones and shales, probably laid down at around the same time as the Sydney Basin. The Lorne Basin stretches from approximately Bonny Hills in the north to Moorland (north of Taree) in the south and west to Mount Gibraltar (south of Comboyne).
Some time after deposition of the basin rocks massive igneous intrusions occurred. Intrusions are liquid rock, magma, that forms under the Earth's surface. This magma is slowly pushed up from deep within the earth into any cracks and spaces it can find, pushing the existing rock out of the way, in a process that can take millions of years. As the rock slowly cools, the different parts of the magma cool in to crystals. These Late Triassic (between 235 and 201 million years ago) igneous rocks are mostly a micro-granite, though occasionally rhyolite is found. Rocks are composed of quartz, mica, augite and feldspar. They were more resistant to erosion than the surrounding sedimentary rocks and formed the Three Brothers Mountains.
Microgranite is a medium-grained intrusive igneous rock. It contains crystals, smaller than grains of rice, which are interlocking and randomly oriented. It is pale grey and can sometimes be pinkish in colour. It contains a number of minerals, mostly feldspars, which are pale grey or pinkish, and quartz, which is grey or white. It also contains small specs of mafic (dark coloured) minerals.
Microgranite is the medium-grained equivalent of granite. The crystals are slightly smaller than granite indicating that the magma cooled more quickly. It usually occurs in smaller intrusions than granite. Microgranite forms from magma that contains a lot of quartz (silica).
The igneous rocks of the North Brother Mountain were used for construction in the local area. Quartz rock from the Laurieton quarry, just outside the eastern boundary of the park, was used to build the Camden Haven breakwater in the late 1890s and to extend and repair the breakwater in 1968-73.
North Brother Mountain rises from just above sea level to a height of 487 metres and most of the park is steeply sloping. It is an important and prominent landmark in the local area, being visible from Smoky Cape at South West Rocks to Cape Hawke near Forster and out to sea. It has long been recognised for its aesthetic value and for the views from the summit.
Flora
A flora survey of the park was undertaken by Kendall & Kendall (1997). Eight forest associations were identified within the park, which fall within the broad categories of dry sclerophyll forest, wet sclerophyll forest, rainforest and grassland. Two of the wet sclerophyll communities (the red gum forest and brush box forest) are inadequately conserved in the region. The white mahogany association is also considered to be inadequately conserved regionally (less than 5%). However, due to the complexity of this group of forests, conserved areas are unlikely to cover the full range of variations (Benson & Hager in Kendall & Kendall, 1997). Comparatively little logging occurred in steep and difficult to access areas of the park. Consequently some of the best examples of old growth blackbutt in NSW and valuable rainforest pockets occur on North Brother Mountain.
The park also contains two plant species (Acacia courtii and Melaleuca groveana) listed as vulnerable under the Threatened Species Conservation Act 1995. Acacia courtii has only been recorded from North Brother, South Brother and Middle Brother Mountains and is conserved only within the Dooragan and Middle Brother National Parks. This species is considered to be at risk of extinction in the wild within 20 to 50 years under present or known potential adverse conditions (Briggs and Leigh
1988).
Fauna
The park contains significant elements of old growth forest, which are crucial to the survival of many species of wildlife. Pockets of sub-tropical rainforest contain habitat that provides an important food supply for migratory fauna such as the rainbow beeeater Merops ornatus and wonga pigeon Leucosarcia melanoleuca, locally nomadic fauna (such as the Queensland blossom bat) and sedentary fauna (i.e. rainforest snails). The park is the Australian Museum's southernmost record for Brazieresta larreyi, a rainforest snail. The park supports a diversity of native animals including species listed as vulnerable under the Threatened Species Conservation Act 1995. These include the glossy black cockatoo Calyptorhynchus lathami, wompoo fruit-dove Ptilinopus magnificus, yellow-bellied glider Petaurus australis, greater glider Petauroides volans and the little bent-wing bat Miniopterus australis. Other threatened species likely to occur in the park include the powerful owl Ninox strenua, masked owl Tyto novaehollandiae, Queensland blossom bat Syconycteris australis, spotted-tailed quoll Dasyurus maculatus, brush-tailed phascogale Phascogale tapoatafa and the squirrel glider Petaurus norfolcensis.
Cultural Heritage
Dooragan was the name given to North Brother Mountain by the local Aboriginal people. The park is an important area to local Aboriginal people, not only mythologically, but because the mountain is seen as a protector of the area (Bert Marr, Birpai elder, quoted in Van Kempen, 1997). To the Aboriginal people, the Three Brother Mountains are the focus of a Dreamtime story of three brothers of the Birpai tribe who lived near the Camden Haven River. When the youngest of the three separated from his two brothers, they were killed by a witch-woman. The young man killed the witch-woman and buried the remains of his two brothers at the site of North and Middle Brother Mountains. Then he went to South Brother Mountain and, because he was ashamed that he had not saved his two brothers, he killed himself. The spirits of Creation stirred that night and where each body lay a mountain arose to mark the tragedy. The mountains were known to the Aboriginal people as the Three Birrooguns. (R. Kelly 1976, and Van Kempen 1997). The declaration of the entire park as an Aboriginal Place recognises its significance as part of local Aboriginal stories and for ceremonial purposes. The summit of North Brother Mountain is likely to have been used as a lookout and possibly for ceremonies. The mountain was probably also a food source as cycads Macrozamia spp. grow on the mountain, and the nuts of cycads were an important food for Aboriginal people in the Port Macquarie area. Aboriginal communities associate natural resources with the use and enjoyment of valued foods and medicines, caring for the land, passing on cultural knowledge and strengthening social bonds. North Brother Mountain is within the Purfleet-Taree Local Aboriginal Land Council area and the Birpai tribal area.
You can drive or walk to the summit of North Brother mountain, and to claim the find, you need to answer the following questions:-
1. How high is North Brother?
2. How is microgranite formed, compared to ordinary granite?
3. Are microgranite crystals bigger or smaller than grains of rice?
4. What is an igneous intrusion?
5. Who actually named North Brother mountain?
6. Who was Commissioner for Forests NSW in 1970, when the access road was opened?
7. In addition to answering the questions, you can optionally take a photo of yourself and your GPSr at one of the lookouts, and post it with your log.
Please log as found and email the answers to Stoke Bunnies, if there's anything wrong, we'll be in touch.
There are 2 traditional caches on the mountain to find, so it's a very worthwhile visit. Enjoy the mountain, the history, and the views.