Geologists tell us, that there is a great plume of molten hot lava pressing up from deep within the mantle of the earth. They tell us, that plume, the Hawai'ian Plume, most simply called the "Hot Spot" is what created and built the Hawai'ian Islands. They say that as the Pacific plate passed over this hot spot, the molten lava forced its way through the seabed hardening to form seamounts, more lava is added and the process repeats. If enough lava is added to the seamount it will poke its top out of the water and become an island. There, more lava may be added and the island grows, as the Big Island is currently doing. Eventually as the plate continues its plodding, never ending movement to the northwest (at the speed of 3 to 4 inches a year - about as fast as fingernails grow) the island will pass beyond the hot spot and no new lava is added. From this point on, the islands are not growing, but are shrinking, due to erosion. Seamounts that never get to the surface remain seamounts... seamounts that reach the surface will become islands but inevitably will erode down to atolls, like Midway Island. This is the ultimate fate of each island of Hawai'i. The oldest of the seamounts formed by the Hawai'ian Plume is at the northern end of the Emperor seamount chain. It is 80 million years old and located at the tip of the Aleutian Islands. Of course, there were likely others that were older but they have already disappeared into the Aleutian Trench as the Pacific plate subducts under the North American plate. This chain runs all the way down to where the Hawai'ian Islands have formed. Understanding all this, they say that Kaua'i is 5.1 million years old, and the Big Island started forming as a seamount 800,000 years ago, became an island 200,000 years ago and is still adding real estate today.
This is what the Geologists say, of course, what we know really happened was that the demigod Maui threw his magical fishhooks onto the seabed and then he and his brothers pulled the islands to the surface. Case closed.
Today we did an initial exploration of Volcano National Park and got a firsthand look at Maui's work.
Halema'umu'u Crater within the Kīlauea Caldera. Note the river of red lava flowing into the lava lake causing ripples, at the front of the lake we saw through binoculars lava fountains 20 to 25 feet high. What looks like white clouds is sulfuric steam.
A view of Kīlauea Caldera from north rim. Note: The well defined layers identifying separate lava events.
When the lava field reaches the ocean these cliffs form and the ocean immediately begin the erosion process.
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