Eberhard Bodenschatz watches 100 million years of geological time pass in an hour. He sees transform faults being created, rift valleys opening and spiralstructures called microplates forming.
But the Cornell physicist does not have an omnipotent view of the planet's ocean floor. Instead he is watching a model of tectonic evolution in a tub of molten wax. "These wax experiments," said Bodenschatz, "allow us to study millions of years of tectonic spreading in thelaboratory. Remarkably,these phenomena appear to be similar to the Earth."
Bodenschatz, an associate professor of physics, presented the latest results from his wax modeling at the centennial meeting of the American Physical Society in Atlanta. His experiments examine phenomena similar to ocean-floor spreading. His experimental apparatus is filled with molten wax. Cold air is blown over the wax surface so that a solid layer is formed. The solid wax layer represents the Earth's cold and hard lithosphere, and the molten wax below, the Earth's plastic upper mantle.
The solid layer ofwax is divided, and the two halves are pulled apart with constant velocity. At intermediate rates of velocity, tiny chunks of solid wax appear at the rift and begin rolling up, something like a rolling snowball gathering snow. Each chunk of wax grows with constant velocity in the direction of the rift, slowing down the rotation rate and resulting in a spiral shape.
Microplates might be created in a similar fashion in the ocean floor. They are structures 100 to 200 kilometers across, the result of a chunk of the lithosphere being caught between two moving, overlapping plates. These ocean-floor microplates rotate by 18 degrees in about one million years, corresponding to just a minute in the wax tub.
Bodenschatz made it clear that his experiments are only a model for ocean-floor spreading and are not an exact replica. "The wax gives me a reasonable approach to model such processes in the Earth," he said. "I don't want to say I do the Earth. I do wax." Contributing to the research were Cornell graduate student Rolf Ragnarsson and undergraduates William Bertsche, Richard Katz, Nate Gemelke and Jeron Carr.
| Cornell Chronicle Front Page | | Table of Contents | | Cornell News Service Home Page |