Open areas remain from the extensive early clearings. Remains of mining activity can be seen feom the 4WD track. While rich pockets of ore occurred, the deposits were mainly low-grade. Though more than 70 men were employed for a short time, the mines were never a financial success. Old surface diggings are scattered throughout the Red Rock area.
Sundown is known locally as 'traprock' country.
The hard dense rock was formed from ancient marine sediments deformed by heat and pressure. Intense minor faulting, folding and weathering has resulted in the existing layered rocks forming steep ridges and gorges and gorges leading down to the Severn River. Intrusions of granite occur at Jibbinbar Mountain in the north-west and the deeply eroded Red Rock gorge. Two granite dykes run roughly parallel through the area. One forms Rats Castle, a local landmark, and can be traced through the park and across the road near the southern entrance.