BTW, for those who have not heard, Gene Shoemaker died this summer, in
an auto accident while doing field work in Australia. Shoemaker was a
well known and articulate astronomer/geologist/planetary scientist, most
famous for discovering comet Shoemaker-Levy, which crashed spectacularly
into Jupiter in 1994. He had made his mark earlier by establishing the
extraterrestrial origin of Meteor Crater, near Winslow, Arizona.
My wife took an intro geology class from Shoemaker when she was in college,
and he had always been one of her favorite instructors.
Hal