Science: Benevolent Blisters

The earth has "boils" that form in its rocky flesh, rise toward its skin, and sometimes break through. Proper appreciation of these ailments, said Geologist C. Wroe Wolfe of Boston University last week, should lead to the discovery of valuable ore deposits.

Professor Wolfe believes that radioactive elements (e.g., uranium and thorium) in the deep rocks gradually release heat. Since rocks are poor heat conductors, the heat cannot easily escape. After millions of years, the temperature rises until a vast blister of hot, expanded rock has formed. If it works its way to the surface, or if cracks appear, the hot rock...

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