A project from the National Trust of WA
A self-guided drive trail between the Perth Hills and Western Australia’s Eastern Goldfields. Go with the Flow. Follow the water to discover more about the audacious goldfields water supply scheme and Engineer CY O’Connor.
“Future generations, I am quite certain will think of us and bless us for our far seeing patriotism, and it will be said of us, as Isaiah said of old, ‘They made a way in the wilderness, and rivers in the desert”
You will not fail to notice magnificent outcrops of exposed granite as you travel from the Perth Hills through the Wheatbelt to the Eastern Goldfields.
The Yilgarn Craton which extends over some 650 000 sq km of Western Australia, from Meekatharra and Wiluna in the north to the south coast and from Yamarna and Balladonia in the east almost to the west coast, is Australia’s largest granitic area. It is also one of the oldest landscapes in the world. The granite was formed from molten rock, known as magma, which solidified deep within the earth’s crust. It was finally exposed at the surface as the surrounding soil was eroded.
Sites along the Heritage Trail include several particular granite outcrops such Merredin Peak, Kellerberrin Hill and Totadgin Rock, known as inselbergs, or “island mountains”. You will pass others, such as at Yellowdine. Typically domed shaped, inselbergs rise abruptly from the surrounding plains like islands in the sea. The analogy goes further – because they are isolated in a sea of sand, rather than water, these rocks are often home to unique flora and fauna.
Sometimes the lower slopes of inselbergs are undercut, forming a wave like shape. The undercut is probably formed by chemical weathering in water saturated soil beneath the surface at some time prior to the rock’s exposure.
Rock holes known as gnammas are often found on the top of domed inselbergs and were an important source of water for Aboriginal people. There are two types of gnammas. The more common pan-gnammas have flat bottoms and steep, sometimes overhanging walls. A large one could be 8 m across with a depth of 20 cm. The rarer pit-gnammas are typically hemispherical and have a large depth relative to their surface area – perhaps 55 cm deep and 1 m in diameter.
Many of these granite outcrops were harvested for water before the goldfields water supply scheme was built. The rock became a catchment system using gravity and the natural surface of the rock to divert rainwater to a central collection area. The site of Tammin’s Hunts Well has a small stone-lined dam fed by the same source, but walls, weirs or tanks were constructed for larger water yields, such as for railway dams required to supply steam engines on the Eastern Railway.
Click on any map section or place below to discover The Golden Pipeline.