Dinosaur Killer - Four Revolutions in the Earth Sciences - page 177

and prevent further wars. 4 Thirty-five years later, father and son would uncover
evidence of an explosion more than ten thousand times larger than the one Luis
had witnessed above Hiroshima.
After the war, Luis returned to Berkeley to study subatomic particles produced
in cloud chambers, work for which he won the Nobel Prize. His 1968 Nobel cita-
tionwasoneofthelongestinthehistoryoftheprizeatthattime.Buthavingascen-
ded to the summit in his chosen field, what does a scientist do next? A move into
geology seemed unattractive, for in spite of his son Walter having chosen the field,
Luis confessed a pronounced lack of enthusiasm. Then one day in the mid-1970s,
returning from a field trip abroad, Walter produced a specimen that sparked Luis's
imagination and, as he put it, “rejuvenated his career.” 5
Walter Alvarez (b. 1940) earned his doctorate at Princeton under Harry Hess,
then worked as a petroleum geologist in Libya. He joined the faculty at Berkeley,
where he became interested in magnetic reversals. One section of the magnetic
timescale that required more work was near the K-T boundary, 65 million years
ago, where there are many short magnetic events whose detailed chronology sci-
entists needed to sort out. An especially complete K-T section outcropped near
the small Italian mountain town of Gubbio, where Walter journeyed in the sum-
mers to collect samples. The K-T boundary at Gubbio is easily visible to the na-
ked eye. Below it, owing to the presence of white-shelled fossil foraminifera, the
rocks are white. Above the boundary, almost all the “forams” have disappeared,
and the rocks are dark. But the forams were not the only ones to disappear at the
K-T boundary: so did the dinosaurs.