[1] The North Shore and the Berowra Valley National Park[2] are located on the Hornsby Plateau.

The plateau rises from the Cumberland Plain in the south along a warp line increasing from the proximity of Cattai to Botany Bay.

At the end of the Tertiary period, or about 80 million years ago, earth movements created an upheaval of 600 metres in most of coastal eastern Australia, due to the rifting and opening of the Tasman Sea.

Thus, these movements created the Blue Mountains and Hornsby Plateaux, with the lagging behind of the peneplain becoming the Cumberland Plain.

[5] The plateau was scoured by freshwater streams, which perforated a labyrinth of V-shaped valleys with intruding rocky ridges into the Hawkesbury Sandstone.