Research by Denison University emeritus professors Robert Malcuit and Ronald Winters on the origin of the moon will be presented by Malcuit at the 119th annual meeting of the Geological Society of America. The meeting will be held Oct. 27-31, 2007, at the Colorado Convention Center in Philadelphia. Approximately 6,300 geoscientists are expected to attend.

The research by Malcuit, of the Department of Geosciences, and Winters, of the Department of Physics and Astronomy, is on whether early archean ophiolites and the cool early earth can be explained in the context of a tidal-capture model for the origin of the moon.

A major debate in the geological sciences is whether or not the early Earth (from 4.4 to 3.6 billion years before present) was cool enough to have ocean water on the surface. The main documents for this era of earth history are in the form of zircon crystals from the Jack Hills Formation in Western Australia. The oxygen isotope ratios in these zircons strongly suggest a "Cool Early Earth," cool enough to have ocean water on the surface. The other debate in the planetary sciences concerns the origin of the Moon. Was it formed during a giant collision between a Mars-sized body and the primitive Earth? Such a collision would have enough energy to completely melt the Earth and vaporize all the material that would eventually form the Moon. Such a scenario would result in a "Very Warm Early Earth." Or was the Moon captured by the Earth about 3.9 billion years ago? The Malcuit and Winters capture model is compatible with the concept of a "Cool Early Earth" because there would have been no moon (and no lunar tides) during the first 650 million years of earth history. (Earth formed about 4.55 billion years ago.)

"In our paper," Malcuit says, "we demonstrate that the Earth would remain cool enough throughout the capture process to have ocean water on the surface (a concept that is consistent with the information from the zircon crystals). The key factor is that the Moon gets very hot during the capture process because it must dissipate well over 90 percent of the energy for its own capture. The bottom line is that the Earth is tidally disturbed during the capture process, mainly in the equatorial zone, but does not absorb much thermal energy during this very unusual era in the history of the Earth."

For information, contact Malcuit at malcuit@denison.edu or call (740) 334-3746.

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About Denison:

Denison University, founded in 1831, is an independent, residential liberal arts institution located in Granville, Ohio. A highly selective college enrolling 2,100 full-time undergraduate students from all 50 states and dozens of foreign countries, Denison is a place where innovative faculty and motivated students collaborate in rigorous scholarship, civic engagement and the cultivation of independent thinking.

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