South West Riverstone
South West Riverstone was established in 2000 in Boyup Brook in the South West region of WA. Here we quarry natural rounded river stones, rocks and gravels for gardens and landscapes throughout WA
For sizes, quantities and coverage please see the Products page.
Quarry Geology
ABOUT US
The quarry is situated on the highest point of the landscape in an ancient glacial bed which overlooks the Blackwood river. Although referred to as "riverstone" the stone dug from a glacial deposit at the top of a hill and not out of the river. This deposit is the result of an ancient glacier that was moved here from what is now Antarctica.
The stones are rounded and smooth, initially from being pushed along by a glacier then later due to the action of enormous volumes of water running over them as a result of melting ice.
The glacier bed is considered to be one of the major drainage basins for the South west at that time running from south of the Stirling Ranges to off the Darling Scarp near Kirup.
The stone is embedded in kaolin clay which is a very fine white clay formed by the weathering of feldspar. Due to the harsh actions of the tumbling stones and massive glacial fluvial flows that occurred, no fossils have been found and not likely to.
This has made it very hard to pin an exact date of the formation of the stone, however the late cretaceous, 65 million years ago (the end of the Dinosaurs era) seems to be the favoured estimate. The formation stretches for some 80 km however it is buried deep ground except for this area of private property where the Blackwood River has cut through the hill exposing the stone.
The quarrying process begins with the stone and clay being dug out by heavy earthmoving machinery and being processed to separate the stone from the clay. The stone is then screened into various sizes and then washed to remove any residual clay. The final product is then either placed into 1tonne bulka bags or trucked out in bulk . The larger stone is hand picked to remove broken stone and the surplus larger river rocks are crushed to produce small aggregate.