Browns Waterholes creek has cut a channel through to a bedrock of granite 360 million years old (Devonian Era). You can see this rock in boulders downstream and in the highway cutting to the east. It erodes to form sand.
The high ground immediately to the west is formed from sedimentary rock, a laterite, laid down 30 million years ago (Tertiary Era). This ridge of rock, the Boomerang Ridge, was once a tree covered area in a fairly treeless plain. You can see this rock in cuttings at the Lismore end of the Skipton Road.

Towards Derrinallum, lava flows of plains basalt (1-2 million years ago) and stony rises basalt (about 20 thousand years ago) formed the western plains and eroded to form the soils of a rich farming area extending to the South Australian border. The underlying basalt rock was called ‘bluestone’ and used for building.
The crossing at the creek and the nearby Boomerang Ridge made this an enticing place to settle. John Brown became the frst white settler in 1840, staying longer than expected when the axle of his bullock dray broke in the creek. In 1861 the settlement of Browns Waterholes was proclaimed the town of Lismore.