The river system of Sutherland Shire has undergone significant transformations since the Tertiary period, marked by a gradual tilting south of the Georges River. This slow uplift, occurring over several million years, led to the formation of the Woronora Plateau, a gentle rise in the landscape to the south. Consequently, the river courses within the Shire adopted steeper gradients, intensifying their flow and sculpting the dramatic gorges of the Woronora, Hacking, and Georges Rivers, along with their tributaries. This dynamic geological activity has resulted in the creation of stunning waterfalls, including those at Waterfall and Undola.

The Shire's water supply is primarily sourced from the surface, with the Woronora Dam—constructed within the deep gorge of the Woronora River—serving as the main reservoir. Additionally, underground water sources supplement the region's water needs, providing a vital resource for residents.

During the last ice age, the rivers were tasked with the significant geological challenge of cutting through rock layers to reach the ocean. This erosion process contributed to the distinctive "valley-in-valley" shape of the deep gorges visible throughout the Sutherland Shire today. As sea levels rose post-ice age, sediment carried by these rivers accumulated, filling the area between Kurnell—originally an island—and Miranda. This sedimentation led to the formation of sand dunes in Kurnell and the mud and sand flats of Quibray and Gunnamatta Bays.

While the Kurnell sand dunes have provided a valuable source of sand for construction in the southern suburbs of Sydney, the extensive extraction has taken a toll on the area’s natural beauty. The removal of vegetation has accelerated erosion, altering the landscape and posing challenges for environmental conservation. As the river system continues to evolve, the interplay between natural processes and human activity will remain a critical consideration for the sustainability of Sutherland Shire’s unique ecosystems.