VOLCANIC KAUA’I

There has been some argument over whether Kaua’i formed from a single, major volcano or more than just one. A 2010 study from the University of Hawai’i revealed that there were actually two major shield volcanoes responsible for the island’s formation, one on Kaua’i and one in the region between Kaua’i and Ni’ihau. Ni’ihau is the island located west of Kaua’i and is therefore the remnant of the first volcano.

Once dome-shaped, Kaua’i’s physical appearance has gone through many phases over the past 5 million years. First arising from a submarine volcano (e.g. an undersea volcanic eruption), the island formed when the eruption finally broke the surface of the ocean as a central shield volcano, followed by landslides, shield collapse, and a series of more volcanic eruptions.

There continues to be a constant state of erosion occurring on Kaua’i, and this will eventually lead to the shrinking of the island back into the ocean. Scientists predict this may happen in 2-3 million years.

Kaua’i is fourth in size among the main Hawaiian Islands at 555 square miles of land— it’s 33 miles long and 25 miles wide. Its highest point is near the center of the island at Kawaikini Peak at 5,170 feet. Second highest is Mt. Wai’ale’ale at 5,148 feet. Mt. Wai’ale’ale is literally the wettest spot on earth, with some portions of the summit recorded as receiving 600 inches of rain per year. All of this water feeds the island’s vegetation on a consistent basis, creating waterfalls, streams, verdant valleys and spectacular green and orange cliffs that have given Kaua’i its nickname of “The Garden Isle.”

The Nā Pali Coast of Kaua’i is an example of a shoreline that has been severely eroded by wave action. In the winter months, it is customary for the north and northeast-facing shores to receive surf with heights of up to 40 feet. This wave action is further intensified when combined with Hawaiian trade winds and rains, which cut through the porous rocks like knives. Spectacular sea arches and sea caves have formed in the cliffs as a result of the relentless, pounding surf.