Known as ‘The Grand Canyon of the Pacific’, the Waimea Canyon is a large canyon located on the western side of Kauaʻi in the Hawaiian Islands of the United States. In Hawaiian Waimea means ‘reddish water’, a reference to the erosion of the canyon's red soil.

The canyon was formed by a deep incision of the Waimea River arising from the extreme rainfall on the island's central peak, Mount Waiʻaleʻale. It is approximately ten miles (16 km) long and up to 3,000 feet (900 m) deep.

The canyon is carved into the tholeiitic and post-shield calc-alkaline lavas of the canyon basalt. The lavas of the canyon provide evidence for massive faulting and collapse in the early history of the island. The west side of the canyon is all thin, west-dipping lavas of the Napali Member, while the east side is very thick, flat-lying lavas of the Olokele and Makaweli Members. The two sides are separated by an enormous fault along which a large part of the island moved downwards in a big collapse.

Like the other Hawaiian islands, Kauaʻi is the top of an enormous volcano rising from the ocean floor. With lava flows dated to about 5 million years ago, Kauaʻi is the oldest of the large Hawaiian islands. Roughly 4 million years ago, while Kauaʻi was still erupting almost continuously, a portion of the island collapsed. This collapse formed a depression which then filled with lava flows.

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