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phone: 9765 1200 | facsimile: 9765 1485 | P O Box 2 BOYUP BROOK 6244 | email: keith@boyupbrook.wa.gov.au |
Boyup Brook Shire lies within the Darling Plateau System and consists of three main landform areas:
1. The northern areas of the Shire occupy gently undulating dissected plateau surfaces with broad gravel crests and generally broad valleys.
2. The Central areas have an undulating to moderately sloping plateau surface with some rock outcrops.
3. The Southern portion of the Shire consists of undulating to hilly areas of the plateau surface.
Geology and Minerals
The geology of the Shire is mainly comprised of Precambrian Rocks of the Darling Plateau that are approximately 2,500 years old. The Darling Plateau comprises mainly ancient granites and younger dolerite intrusions. Granite rocks include banded rocks of similar composition called gneisses and magnetite.
Over most of the plateau, basement rocks have been weathered to form a surface capping of laterite - some of which is suitable for use on gravel roads and some with enough potential free alumina to be classed as bauxite. There are potential coal bearing deposits to the north west of Boyup Brook townsite. In the central western portion of the Shire there are metamorphic belts which are known to contain deposits of vandiferous, titaniferous, magnetite and nickel. There is potential for chromitite and platinum group elements. There are also glacial rock deposits occurring throughout the Shire.
There are two known coal deposits in the Boyup Brook Shire. Permian coal, similar to that in Collie, is known to exist in the Wilga Basin (8 km NE of Wilga) and the recently discovered Boyup Brook Basin (2km W of Boyup Brook). Similar to the formations at Collie, there are no surface exposures of coal or coal bearing strata. The exploration effort to date has been inhibited by access difficulties related to the state forest, and to a lesser extent, by failure to conclude compensation agreements with landowners.
It is estimated that coal bearing deposits at Wilga contain a measured resource of 30 million tonnes and an indicated resource of 53 million tonnes with further potential. Tenements are mainly held by Western Collieries, but Griffin Coal also holds some tenements.
A regional drilling program during 1983 discovered the Boyup Brook basin deposit that has coal resources in excess of 90 million tonnes. Most of this small basin occurs in quarantined state forest, hence exploration is progressing slowly and carefully. In 1990, application was made for a mining lease over the area of potentially economic coal development.
Soils
Soils in the north of the Shire consist of duricrust and gravels on broad crests, gravelly soils on slopes and grey sands, yellow sands and earths in wide valley floors.
North-west of Boyup Brook townsite grey leached sands occur with some swampy areas and lakes. West of the town there are gravelly soils on divides and yellow soils and red earths on valley slopes. Central areas, generally between the Blackwood and Tweed Rivers, have yellow gravelly soils and ironstone gravels on gently undulating ridge crests. The southern portion of the Shire has yellow soils, gravel and leached sands in broad valleys.
Vegetation
Much of the Shire area is extensively cleared, with the main areas of remnant vegetation being contained in the large Department of Environment and Conservation (DEC) estate in the Wilga and Perup Reserves. This is predominantly mixed jarrah and marri forest, with important smaller stands of wandoo being found in upper stream valleys. Other significant varieties include banksia found throughout forested areas and wetlands in the west of the Shire.