Science: Rain of Iron

Scientists have known for over 50 years that the great, round pit near Canyon Diablo, Ariz, is a meteorite crater. In Scientific Monthly, Dr. H. H. Nininger offers proof that it was made not by one but by two great meteorites hitting close together.

Scattered for miles around the crater are fragments of meteoric material. The soil itself, in spots, is full of microscopic droplets of nickel-iron (many thousands of them in each cubic foot). The fragments differ in chemical composition; some have melted, vaporized or been altered by heat. By studying such clues for more than ten years, Nininger has reconstructed...