Word: clay
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Dates: during 1990-1999
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...other words, play is children's work, and finding the right materials -- stories, drama, clay, blocks, sand, water, paints -- really means finding the tools for reasoning and maturing. "What's basic and important to any young child's education," says Shelley Lindauer, head of the Lab School Preeducation Program at Utah State University, "is curiosity and observation. It's much more important to know how to go about finding an answer -- not a right answer...
...admission of California and New Mexico into the Union as free states. Said Dabney Taylor, the President's great-great-great grandson: "Rumors have been running through the family for years. I'm just glad somebody is finally going to do something about it." The prime suspects: Senator Henry Clay of Kentucky, Vice President Millard Fillmore and two unnamed Georgia politicians...
...search for the Crater, the first clues were sifted out of clumps of gray clay. At dozens of sites around the world, that clay has been found in a thin boundary layer between the rock of the Tertiary period and the formations of the late Cretaceous period, which ended 65 million years ago. In the Cretaceous rock lie the fossil remains of giant dinosaurs and a profusion of other species. But in the Tertiary formations, just above the clay, no trace exists of the dinosaurs or many of the other Cretaceous species...
...Alvarezes analyzed this clay in the late 1970s and showed it had a far higher content of the rare element iridium than ordinarily found in the earth's crust. It was this discovery that led Luis Alvarez to his momentous - insight. Comets and asteroids have high iridium content, he reasoned, and the clay layer could have been formed by the worldwide fallout of the material vaporized when an errant asteroid or, as most scientists now suspect, a giant comet smacked into the earth...
This week, at an astronomy conference in Flagstaff, Ariz., scientists will add an intriguing twist to the Alvarez scenario. Their interpretation is based on new evidence that the Cretaceous-clay boundary actually consists of two parts: a thin layer overlying a more substantial one. To Eugene Shoemaker, of the U.S. Geological Survey and a co-author of the report, two layers indicate not one but two impacts...