By Katie Twaddle
Photo by Na Pali Riders Raft Tours
While we think of Kauai as a paradise, its geology does not emulate a carefree or simple existence. Kauai’s past is complex, exciting, dangerous, and as unstable as its future.
Since the discovery of Kauai in 1778 by Captain Cook, the island’s lush valleys, high cliffs and soft, sandy beaches have been the distinguishing characteristics that draw so many to the Garden Island. But below the surface there is much more to Kauai’s magnificent beauty and terrain. There is a great past hiding within waterfalls, lava dikes and valleys.
About 5 million years ago there was a volcanic eruption along the Hawaii-Emperor Volcanic chain. The eruption sparked the beginning of the Hawaiian Islands and ultimately formed Kauai island, the oldest island in the main Hawaiian island chain. Continuous volcanic activity, formed each Hawaiian island, beginning as an underwater mountain that eventually rose above the surface of the ocean. Kauai went through three stages of development: 1) shield; 2) post-shield; and 3) rejuvenation. The shield stage refers to the first exposure of igneous and metamorphic rock, which became the foundation for the landmass. In the post-shield stage the volcanic eruptions slowed down. The lava dried and the excess magma invaded the previously formed rock, creating lava dikes and tubes on the cliffs. Finally, in the rejuvenation phase streams and rivers formed into valleys within the huge mountain that was early Kauai.
The countless volcanic eruptions ended up creating an initial island size of 1,155 square miles. Its highest peaks stood at nearly 8,500 ft. But because Kauai developed so rapidly, the actual structure of the island was weak.
‘The resulting instability of such rapid growth … led to major structural failures such as the probably normal fault that formed the west escarpment of Waimea Canyon, … and