Geoscience Reference
In-Depth Information
it. Brown realised that the answer to this problem might lie in iron
meteorites which he knew contained lead but did not contain any
uranium, and so the lead must have been present when the Solar
System and the Earth first formed. If the research team could deter-
mine the isotopic composition of meteoritic lead they could use this
information to plug into the Holmes-Houtermans Model and derive
the true age of the Earth.
Patterson began his post-doctoral fellowship at Chicago by sub-
mitting a proposal to the Atomic Energy Commission for funding
which would allow him to carry out this work. The proposal was
rejected, but Brown was having none of it: he resubmitted the proposal
in his own name and Patterson received the funds. Within a year Brown
was appointed to a position at the California Institute of Technology
and so Patterson and his family migrated to the West Coast. He was to
remain in the employ of Caltech for the remainder of his career.
Brown built new facilities in Pasadena and installed Patterson
where he succeeded in isolating the primeval lead from the Canyon
Diablo meteorite (Figure
14.2
). This is probably the most famous
meteorite to fall in North America: it crashed into the Earth some
50,000 years ago and formed the impressive crater in Arizona. On
impact huge volumes of dust would have been thrown sky high, in a
manner similar to that of a nuclear explosion, and fragments of the
rock and meteorite fell back to the ground. Bits of the meteorite were
thrown several miles into an adjacent canyon fromwhich the meteor-
ite derived its name. To extract the lead Patterson had to slice the
meteorite open, and pick out some of the black sulphide that occurred
in small pockets. He then dissolved this in acids and picked out the
tiny fragments of lead which he placed securely in a small glass vial.
Carefully packing up his samples of isolated lead, Patterson flew to
Chicago in early 1953 where he stuck it into a mass spectrometer
in Mark Inghram's laboratory at the Argonne National Laboratory
run by the University of Chicago. Inghram (1919-2003) invented and
modified these instruments, which according to Jerry Wasserburg
'were his favorite shovels for excavating new areas'. Making sure that
