Haleakala National Park - Hot Spots

For some unknown reason, about 125 areas beneath the earth's surface -- "hot spots," scientists call them -- generate more magma than others. The Hawaiian hot spot, which has produced molten rock for at least 70 million years (and is still going strong), is one of the largest in the world. Like a perpetual fountain continually bubbling up lava, it has, all by itself, created each and every one of the Hawaiian Islands, and even now it is in the process of giving birth once again.

Although a hot spot is stationary, the crust of the earth is not. Broken into about a dozen pieces like a cracked eggshell, the crust slides over the earth's mantle, one piece occasionally bumping into another. These pieces, called plates, support and pull along the material on top -- the continents and the seas. Just as a cloud drifts lazily across the sky, the Pacific Plate moves over the hot spot, and an island is magically created from the molten rock. As the plate drifts northwestward at a speed of four inches a year, it pulls its new island away with it, and another part of the plate moves into place above the fiery fountain. This process has been taking place for millions of years, and the result is a chain of volcanic islands strung out like smoke signals from the island of Hawaii to Kure Island, more than 1,500 miles away.

But whatever Mother Nature builds, she eventually tears down. When it comes to permanence, a mountain or a volcano, for all its massive bulk, is as vulnerable as shifting sands. The older "islands" in the Hawaiian chain, those at the extreme northwest end, are greatly eroded -- so much so that not even their peaks are visible above the waves. The islands get progressively younger toward the southeast end, where eight rise in various stages of youthful splendor. Kauai, about 5 million years old, and Oahu, 3 million years, are already weathered: erosion has worn away the volcanoes' top coats, exposing their inner flanks. The youngest island of all, Hawaii, less than a million years old, still has its youthful dome shape.

Older than Hawaii, the island of Maui began forming over the hot spot more than a million years ago. At that time, Maui was in the location now occupied by Hawaii, which did not yet exist. Since then, Maui has drifted about 100 miles to the northwest, and the eruptions of Haleakala, its biggest volcano, have waned as it slips from over the hot spot.

Youngsters are impetuous, often temperamental and volatile. But as years pass, the youth turns into maturity, they eventually become subdued and cease to blow their tops. So it is with volcanoes. The youngest in the Hawaiian chain, Mauna Loa and Kilauea on the island of Hawaii, are still spitting fire; but as the island moves form the hot spot, its flames will become smoldering embers, as have those of its older neighbors.

It took scientists many years to figure out that the Hawaiian volcanoes have become progressively quieter, and to develop the hot spot theory. Hawaiians have understood the basics for generations: they told and retold stories of the goddess of fire, Pele, recounting her travels as she moved from Kauai to Oahu to Maui to Hawaii, her current home. Pele is easily angered. When she stamps her foot, the earth trembles; at her command, the mountaintop erupts.