Waianae Range

Waiʻanae Range is the eroded remains of an ancient shield volcano that comprises the western half of the Hawaiian Island of Oʻahu. Its crest, at Kaʻala, is the highest peak on Oʻahu at 4,025 feet.

Like the neighboring Koʻolau, the Waiʻanae Range is not a mountain range in the sense most people are familiar with, as the mountain range as a whole was created from a single volcano rather than plate tectonics.

The oldest lava dated from the volcano are about 3.9 million years old. About 3.2 million years ago, the volcano's activity changed, the rate of eruption started to decrease and the composition of the lava erupted from the volcano changed. The volcano is thought to have last erupted about 2.5 million years ago.