Landscape and Geology of Monjebup Reserve

The landscape of this south-west region is shaped from granites of the ‘Yilgarn Block’, the oldest intact land surface on Earth. Closer to the south coast of Western Australia, there are quartzite rocks that contain fossils of the earliest known life on Earth. The properties that Bush Heritage is acquiring straddle what would have been an upper limit of the Eocene seas that covered large areas of the south coast when the Australian continent was finally breaking way from Antarctica.

Even after 40 million years it is possible to see the geological formations created in the warm, shallow seas. Embedded in the soft rock are millions of minute silica spicules, which once formed the skeletons of ancient sponges. The old shoreline is still visible today and glistens in the sun as water seeps down the steep granite slopes.

There are a number of landforms on Monjebup Reserve, including upland duplex soils, breakaway complexes, rocky slopes and hilltops, sandplains and creek systems. Parts of the area have been described by the National Trust of Western Australia as ‘extremely rocky and steep with areas yet to be explored by Europeans’. It is the ‘healthiest-looking’ and ‘least disturbed’ area of private bush likely to exist in the whole Fitzgerald to Stirling area, and is virtually trackless – as close to pre-European condition as anywhere in south-west Western Australia.

This rich and diverse landscape results from a combination of great geological age, a long history of climate change and an intense and fine-scale mosaic of different soils, landforms and habitats. Consequently, we now have very diverse and complex habitat ‘patchworks’ supporting characteristic and varied plant and animal communities.