Geoscience Reference
In-Depth Information
tablishment, Baldwin set out to prove his critics wrong. He would show that the
Moon is a worthy subject for study and that his theories were sound.
Baldwin's first major contribution to lunar geology was his 1949 topic
The Face
of the Moon
. Like Dietz, Baldwin was unaware of Wegener's pamphlet on the sub-
ject, but all three came to the same conclusions. The topic included a logarithmic
graph of depth versus diameter for 329 lunar craters. The data points fell on a
smooth curve: over a range of diameters of more than 150 times, the wider the
crater the deeper. The clincher came when he plotted on the graph the dimensions
of explosion pits from wartime mortar and bombshells. Though smaller than the
lunar craters, these known explosion craters fell right on the lunar curve. Baldwin
concluded that “the only reasonable interpretation of this curve is that the craters
of the Moon, vast and small, form a continuous sequence of explosion pits, each
having been dug by a single blast. No available source of energy is known other
than that carried by meteorites.”
4
Baldwin summed up: “To claim that the Moon's craters are volcanic is tan-
tamount to postulating an entirely new, entirely hypothetical mode of origin and
to fly in the face of the fact that a known process is completely able to explain
the vast majority of observed lunar features” (146). But in 1949, hardly any sci-
entists were interested in the Moon and its craters. To them, the matter appeared
long settled: lunar craters are volcanic, and, moreover, so are all putative terrestrial
impact craters. Fortunately, there were a few who did not see it that way.
Shock Waves
One who read
The Face of the Moon
was the Nobel laureate and chemist Harold
Urey (1893-1981). The topic so inspired Urey that he made the origin of the Moon
and planets the focus of his life's work. Another was Gene Shoemaker. When
Baldwin's topic appeared, Urey was already famous; at age twenty-one, Shoe-
maker was not famous—yet. Like Harry Hess, Urey was often grandly wrong.
Again like Hess, when Urey was wrong he promptly admitted it and modified his
ideas to incorporate the new evidence. If anything, Urey may have been too ready
to change his mind. But how much better that than a refusal to debate or to admit
new evidence.
Urey read Baldwin's topic on a Canadian train trip. On his return, he lined his
office with lunar photographs and became consumed with the Moon. He was not
particularly interested in the origin of lunar craters, having no reason not to accept
Baldwin'sdocumentedconclusionthattheywerecausedbyimpact.Urey'sinterest
