Geoscience Reference
In-Depth Information
son won the Tyler Prize for Environmental Achievement. His letter of nomination
said in part, “Patterson has never slanted statements of his results to accommodate
or placate special interests, either within the scientific community or outside. . . .
The lesson has been given to other scientists that, if they have the vision, their . . .
work has the potential to immediately affect the wellbeing of the world.”
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After Patterson's 1956 paper, scientists went on to measure the ages of many
other meteorites, of a number of rocks from the Moon, and of countless rocks on
Earth. Along the way, they extended the “isochrone” that Houtermans had inven-
ted, allowing them to obviate the two main pitfalls of age dating: the possible pres-
ence of original daughter atoms and the possible loss or gain of atoms.
FIGURE 5
. Geologic timescale
Source
: G. B. Dalrymple,
Ancient Earth, Ancient Skies: The
Age of Earth and Its Cosmic Surroundings
(Stanford, Calif.: Stanford University Press, 2004).
As one example of the success of the methods, let us consider a meteorite re-
cently found lying on the ice at the La Paz Icefield in Antarctica. Five different
teams measured its age using four different parent-daughter pairs. Each gave the
same result, three billion years, to within a few percent. Had one or another of the
assumptions that underlie age dating been violated, these different methods could
not have given the same result. (This meteorite is especially interesting because it
came from the Moon, blasted off by the impact of another, much larger meteorite.)
Brent Dalrymple has tallied the ages of specimens from the Moon returned by
the Apollo missions, some of which give ages as old as Patterson's meteorites. As
he reports: “Even the most conservative interpretation of the age data . . . leads to
the conclusion that the Moon's age must equal or exceed 4.5 billion years.”
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