Karl Karlstrom, professor, structural geology and tectonics, University of New Mexico
Ivo Lucchitta, emeritus scientist, USGS, research associate, Museum of Northern Arizona, Flagstaff, Ariz.
Richard Young, professor, geological sciences, State University of New York, Geneseo
The Grand Canyon may seem to be a simple case of "river carves rock," but to geologists, its formation is still puzzling. Ira Flatow and guests discuss the canyon's mysteries, and the scientific sleuthing being done to solve them—millions of years after the Colorado River carried off the evidence.