Around 70 million years ago, violence occurred in the Earth’s mantle, deep below the ocean floor. Hot liquid rock blasted through the Pacific plate like a cutting torch, forcing liquid rock to the surface forming the Emperor Seamounts off the coat of Russia. As the tectonic plate moved slowly over this hot spot, this torch cut a long scar along the plate, piling up mountains of rock; thus creating island after island.
As soon as these islands were created, earth’s elements converged to try to destroy them. Ocean waves battered the fragile rock. Abundant rain pummeled creating faults in the rock making rivers and streams. The waters carried away the rock and soil, everything that was needed to keep the islands viable. Even more, the sheer weight of the islands ensured their doom. Lava flowed on top of other lava, making the island unstable as they were crushed under the weight of subsequent lava flows, causing the mountain’s summits to sink back into the sea.
The oldest of these islands to survive is Kure. Once, teaming with life, it is now, sadly, an atoll (a dead island). Other islands were created to replace those that sank into the sea. The Hawaiian Islands are the latest in this grand island-making process. Of all the Hawaiian Islands, Kauai and Ni’ihau are the oldest of the eight major ones. The last of Kauai’s fires died out one million years ago. O’ahu, Lanai, Moloka’i, and Kaho’olawe are over their growing days too.
Maui is in her twilight as a growing island. After a vigorous growth cycle, islands usually go to sleep for a million years or so before having one final blow. Maui’s volcano, Haleakala, awoke in 1790 with a large blow, and will have some regular spirts until it finally dies into its eternal sleep.
The newest island in the Hawaiian Island chain is the Big Island, Hawaii. Born less than one million years ago, Hawaii is still growing. There are five volcanoes on Hawaii. All are still considered alive, but the hard work being done there these days are by the Mauna Loa and Kilauea. The latest cycle of eruptions started in 1983 and 1984, respectively; and continues to spirt.
After the lava flowed and the islands cooled, marine life came, then fish, then coral polyps attaching themselves to the lava flows to create coral reefs for the marine life and fish. On shore, storms sent wayward birds to the islands. Other animal life found their way to the islands via floating debris washed up on the islands.
Just like people, islands have a life cycle. They experience a violent birth, growth, carving up and collapse, then sinking back into the sea. How can you tell where islands are in their life cycle?
- A sandy, silver island without mountains, called an atoll, is an old island.
- A lush, green island like Kauai and O’ahu is middle-aged.
- A dynamic island full of volcano activity like Hawaii is young.
Cite: O’ahu Revealed by Andrew Doughty