 The northern and southern headlands featuring Hawkesbury sandstone cliffs which were formed during the Triassic period, between 200 and 250 million years ago.On the Kurnell peninsular, about 20,000 years ago at the height of the ice age the Kurnell headland was a sandstone hill.The old dunes formed much of what is now Botany Bay and the Kurnell headland.