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gen, Bavaria, to visit the nearby twenty-four-kilometer-diameter Rieskessel: the
Ries “bowl” or “kettle.” One feature of the Ries was a peculiar glassy rock named
suevite. Shoemaker recognized on sight that it was a solidified impact melt-rock.
He collected samples and sent them off to Ed Chao, the USGS colleague who had
identified high-pressure coesite in rocks from Meteor Crater. While in Nördlin-
gen mailing the package, the family decided to visit St. George's Cathedral, which
stood above the small town. Shoemaker whipped out his ever-present hand lens
and spotted suevite in the building stone of the cathedral. It would later be found
to contain microscopic diamonds formed when the meteorite struck a bed of rock
departing Meteor Crater, Bucher would still deny that impact had formed the Ries
crater.
Elston subtitled his account of the field trip: “Walter Bucher's Last Field Trip
and Conversion to the Impact Origin of Meteor Crater: A Tribute to an Open
Mind.” This is a jarring epitaph for Bucher, who went to his grave refusing to ac-
cept continental drift, paleomagnetism, and, except for Meteor Crater, meteorite
impact.
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As a few scientists began to entertain the possibility that impact might have
created the craters of the Moon, attention turned to possible terrestrial analogues.
In
The Face of the Moon
, Baldwin listed twelve likely impact craters, excluding
Meteor Crater but including the Rieskessel and the six that Bucher had described
in 1933. Nevertheless, most of the speakers at the 1964 conference on “Geological
Problems in Lunar Research” continued to argue that the Moon's surface features
are volcanic and that there are no terrestrial impact craters. Even proponents of im-
pact, like Baldwin, Shoemaker, and Urey, at the time accepted that many, if not
most, of the smaller lunar features are volcanic.
After hundreds of years of viewing the Moon from a distance that made any the-
ory safe from a reality check, by the mid-1960s the effective distance was about to
close to zero. Surely, scientists would now be able to translate the hieroglyphics of
lunar geology. Surely, the Rosetta Stone of the solar system would now unveil her
long-held secrets.
