WASHINGTON--Ira Gershwin didn't know the half of it. He said the Rockies may crumble, Gibraltar may tumble. But terra firma itself is far from firm.
Even the continents are wandering, half an inch to four inches a year. The Earth is a work in violent progress. The engine of its evolution is heat--boiling gas, molten rock and other stuff--left over from the planet's formation 4.5 billion years ago. The heat frequently bursts through Earth's crust, although rarely as catastrophically as it did 120 years ago on the island of Krakatoa.
If Simon Winchester is correct in his new book--Krakatoa: The Day the World Exploded, August 27, 1883'--the current trial in Indonesia of accused perpetrators of last year's terrorist bombing in Bali may be part of the lingering reverberation of the volcanic eruption--the loudest sound in modern human experience, heard 3,000 miles away--that made an island disappear.
Billions of tons of material--six cubic miles of it--were hurled 120,000 to 160,000 feet in the air. They filtered sunlight, lowering the Earth's temperature and creating spectacular sunsets that for months inspired painters and poets.
And in the East Indies outpost of the Dutch empire, where a notably relaxed and tolerant Islamic faith had long flourished, Krakatoa, by terrifying and dispossessing people, may have catalyzed the much fiercer form of Islam that fused with anticolonialism. It is alive and dealing death today.
Although the people of the East Indies will be forgiven for not appreciating this at the time, Winchester says volcanoes are part of what makes this planet hospitable to humans. They do not erupt so promiscuously as to render the planet unfit for life. And by churning the Earth's mantle, they bring fertile soil and useful minerals to the surface, thereby sustaining the outer earth and the biosphere. For a while.
As Earth heads for frigid lifelessness, the leakage of heat from the Earth's interior causes currents of matter to flow--movements measured in millimeters a year--above the molten core and below the crust. Just as, writes Winchester, ``one sees working in a vat of vegetable soup simmering on the stovetop.''